SINGLE SIGN-ON FRAMEWORK WITH TRUST-LEVEL MAPPING TO AUTHENTICATION REQUIREMENTS

Abstract: A security architecture has been developed in which a single sign-on is provided for multiple information resources. Rather than specifying a single authentication scheme for all information resources, the security architecture associates trust-level requirements with information resources. Authentication schemes (e.g., those based on passwords, certificates, biometric techniques, smart cards, etc.) are associated with trust levels and a log-on service (e.g., 120) obtains credentials for an entity commensurate with the trust-level requirement(s) of one or more information resources (e.g., 191, 192, 193) to be accessed. Once credentials have been obtained for an entity (e.g., 170) and the entity has been authenticated to a given trust level, access is granted, without the need for further credentials and authentication, to information resources for which the authenticated trust level is sufficient.

Description: SINGLE SIGN-ON FRAMEWORK WITH TRUST-LEVEL MAPPING TO AUTHENTICATION REQUIREMENTS Technical Field The mvention relates to information secunty, and more particularly, to systems and method for improving the secunty of information transactions over networks Background Art The internet has become an important medium for mformation services and electronic commerce As the internet has been commercialized, organizations initially established their presence m cyberspace by makmg mformation (typically static, non-sensitive promotional mformation) available on resources well removed from the operational infrastructure of the organization Security issues were often addressed by isolating publicly accessible resources (e g , web servers) from more sensitive assets usmg firewall techniques As long as the publicly accessible mformation and resources were relatively non-sensitive and user interactions with such mformation and resources was not mission critical, relatively simple firewall techniques were adequate Though mformation and resources outside the firewall were at risk, the nsk could generally be limited to non-propnetary mformation that was easily replaceable if compromised Proprietary information and systems critical to day-to-day operations were sheltered behind the firewall and mformation flows across the firewall were filtered to exclude all but the comparatively non-threatening services such as electronic mail However, as the internet has become more pervasive, and as the sophistication of tools and techniques has increased, several aspects of the security environment have changed dramatically First, businesses have recognized the power of information transactions that more tightly couple to operational data systems, such as order processing, inventory, payment systems, etc Such transactions mclude electronic commerce with direct purchasers or consumers (e g , browsmg, selecting and purchasing of books by members of the public from an on-line bookseller) as well as supply chain and/or busmess partner mteractions (e g , automated just-in-time inventory management, customer-specific pncmg, availability and order status mformation, etc ) Commercially relevant transactions increasingly require mformation flows to and from secure operational systems Second, even information-only services are increasingly mission-critical to their providers Corporate image can be adversely affected by unavailability of, or degradation access to, otherwise non- sensitive information such as customer support information, product upgrades, or marketmg and product mformation Because many businesses rely heavily on such facilities, both unauthorized modification and denial of service represent an increasing threat Individual information service or transaction system typically exhibit differing security requirements While it is possible to field individualized security solutions for each information service or transaction system, individualized solutions make it difficult to maintain a uniform security policy across a set of applications or resources Furthermore, individualized solutions tend to foster incompatible security islands within what would ideally be presented to consumers or busmess partners as a single, mtegrated enteφrise For example, a user that has already been authenticated for access to an order processing system may unnecessarily be re-authenticated when accessing an order status system Worse still, a set of individualized solutions is typically only as good as the weakest solution A weak solution may allow an enteφrise to be compromised through a low security entry point Another problem with individualized solutions is a ventable explosion in the number of access controls confrontmg a user As more and more busmess is conducted using computer systems, users are confronted with multiple identifiers and passwords for various systems, resources or levels of access Administrators are faced with the huge problem of issuing, tracking and revokmg the identifiers associated with their users As the "user" community grows to include vendors, customers, potential customers, consultants and others in addition to employees, a huge "id explosion" faces administrators Furthermore, as individual users are themselves confronted with large numbers of identifiers and passwords, adherence to organizational security policies such as password restrictions and requirements (e g , length, character and/or case complexity, robustness to dictionary or easily-ascertamable information attack, frequency of update, etc ) may be reduced As users acquire more passwords — some individuals may have 50 or more — they cannot help but write down or create easy-to-remember, and easy-to-compromise, passwords DISCLOSURE OF INVENTION Accordmgly, a security architecture has been developed in which a smgle sign-on is provided for multiple information resources Rather than specifying a single authentication scheme for all information resources, the security architecture associates trust-level requirements with information resources Authentication schemes (e g , those based on passwords, certificates, biometric techniques, smart cards, etc ) are associated with trust levels and a log-on service obtains credentials for an entity commensurate with the trust-level requrrement(s) of an information resource (or mformation resources) to be accessed Once credentials have been obtained for an entity and the entity has been authenticated to a given trust level, access is granted, without the need for further credentials and authentication, to information resources for which the authenticated trust level is sufficient Individual information resources do not require knowledge of, or specific support for, the specific authentication schemes available or employed at any given time As a result, security architectures and log-on services in accordance with some embodiments of the present invention allow an enteφrise to add, modify or remove authentication schemes or implementations without modification of the mformation resources Some configurations employ pluggable authentication module (PAM) technology Furthermore, secunty architectures and log-on services configurations m accordance with some embodiments of the present invention allow authentication to be performed m accordance changmg security requirements For example, if a particular authentication service is deemed insecure (e g , because compromised or because of a changing threat profile), the trust-level mappmgs to specific authentication services can be updated and have enteφnse- wide effect In one embodiment m accordance with the present invention, an information security system includes multiple mformation resources distributed amongst and executable on one or more servers coupled via a communication network to a client entity, a gatekeeper inteφosed between the client entity and the information resources, and a credential gathering service common to the information resources The information resources have associated trust level requirements Upon receipt of a first request for access to a first mformation resource without prior authentication to a sufficient trust level, the gatekeeper redirects the first request to the common credential gathering service and the common credential gathering service obtains a logm credential for the client entity m accordance with a mappmg rule establishmg a correspondence between the sufficient trust level and a set of suitable credential types In another embodiment m accordance with the present invention, a credential gathermg service provides a single sign-on for sessions that potentially include access to plural information resources having differing security requirements In particular, the credential gathering service includes an input port configured to receive an access request identifying an mitiatmg client entity, means for associatmg a trust level requirement with the access request, an encoding of correspondence between trust levels and credential types, selection logic for selecting (m accordance with the encoding) a credential type corresponding to the trust level requirement, and a credential obtammg interface for requestmg and receivmg a credential of the selected credential type for the initiating client entity In still another embodiment in accordance with the present mvention, a method of providmg a smgle sign-on for plural information resources includes associating credential types with trust levels, specifying for each information resource, required ones of the trust levels for accesses thereto, obtammg at least one credential corresponding to a client entity and authenticating the client entity thereby, and permitting access to any of the mformation resources havmg a specified trust level requirement commensurate with the trust level associated with the authenticated at least one credential In still yet another embodiment m accordance with the present mvention, a method of providmg sign- on in a networked information environment mcludes directing a request for access to a first information resource from an insufficiently authenticated client entity to a credential gathering service, associatmg a first trust level requirement with the access to the first information resource, selecting from plural credential types, a credential type havmg an associated trust level commensurate with the first trust level requirement, obtammg a credential of the selected credential type for the client entity, and authenticating the obtained credential In still yet another embodiment in accordance with the present mvention, a method of providmg a secunty mterface common to plural information resources mcludes associatmg credential types with trust levels and specifying for each information resource, a required one of the trust levels for accesses thereto, obtammg (with a logm service common to the plural mformation resources) at least one credential corresponding to a client entity and authenticating an identity of the client entity thereby, grantmg or denymg access to a first of the information resources based on correspondence between the required trust- level therefor and an authenticated trust level associated with the obtained at least one credential, and grantmg or denymg access to a second of the mformation resources based on correspondence between the required trust-level therefor and the authenticated trust level BRIEF DESCRIPTION OF DRAWINGS The present mvention may be better understood, and its numerous objects, features, and advantages made apparent to those skilled m the art by referencmg the accompanymg drawings FIG. 1 is a block diagram illustrating mformation flows between components m a secunty architecture providing a single sign-on facility with trust-level mapping to authentication requirements m accordance with an exemplary embodiment of the present invention FIG. 2 is a flow chart illustrating operation of a security architecture providmg a smgle sign-on facility with trust-level mapping to authentication requirements m accordance with an exemplary embodiment of the present invention FIG. 3 illustrates mteractions between functional components m a functional decomposition of a security architecture providmg a smgle sign-on facility with trust-level mappmg to authentication requirements m accordance with an exemplary embodiment of the present invention FIG. 4 illustrates relations between login credentials, session credentials and a cookie encoding of a session token in accordance with an exemplary embodiment of the present invention The use of the same reference symbols m different drawings indicates similar or identical items MODE(S) FOR CARRYING OUT THE INVENTION Some terminology used in this specification has meaning particular to the context of embodiments descnbed herem Therefore, to aid persons of ordinary skill in the art m understandmg the full scope of the invention, some of that terminology is now defined Glossary Access Management Systems, methods and techniques for controlling use of information resources Typically, access management systems employ both authentication and authorization to control access to information resources Authentication A process used to verify the identity of an entity As typically implemented, an authentication method is employed to verify the identity of a user or object based on a credential supplied by the user or object Authorization A process for determining whether an identity is permitted to perform some action, such as accessing a resource Typically, an identity will be authenticated, though in some configurations certain identities need not be Credential Evidence of identity used to authenticate an entity Exemplary credentials types include passwords, certificates or other encrypted indicia based on asymmetric, symmetric, public, private, or secret key technologies, one-time passwords, biometric indicia such as by retinal scan, voice print, finger print, etc , and possession based indicia such as smart cards, Enigma cards, keys, etc In some realizations, credentials may be associated with users, sessions, functional objects, etc Digital Signature A transformation of a message usmg an asymmetric cryptosystem such that a person havmg the initial message and the signer's public key can accurately determine whether the transformation was created usmg the pnvate key that corresponds to the signer's public key and whether the message has been altered smce the transformation was made Entity A user or object, including data objects and or functional objects such as applications, components, modules, services, processes, threads, etc , as well as instantiations thereof In some configurations, only user entities (typically, the human prmcipal mteractmg with a software program or on whose behalf a software agent puφorts to act) are considered In other configurations, entities include functional objects without an associated human principal The identity of an entity may be authenticated using a credential Session A period and collection of states spanning one or more interactions between an entity and an mformation environment As used herein a session may span multiple mteractions with multiple resources of the information environment and, m some configurations, may span multiple mformation access protocols (e g , HTTP, FTP, telnet, etc ) A session has a beginning and an end Dunng its existence, a session has state As used herem, the term session connotes a greater persistence than as sometimes used to describe the penod of a "session layer" protocol interaction, which in the case of some protocols, such as HTTP, is generally very short-lived Single Sign-on Security Architecture FIG. 1 provides an overview of major interactions between components for an exemplary security architecture in accordance with the present invention As illustrated in FIG. 1, a client application, e g , a browser 170 operated by a user, mteracts with the security architecture via a gatekeeper and entry handler component 110 and a login component 120 Gatekeeper and entry handler component 110 provides an entry point for external client applications requesting access to enteφrise applications and/or resources, including e g , information resources 191, 192 193, for which access management is provided by the security architecture Using facilities provided by a session management component 160, an authorization component 140, an authentication component 130, an identification component 150, and login component 120, the gatekeeper/entry handler component 110 allows, redirects or refuses access requests m accordance with a security policy Individual information resources typically have differing security requirements In addition, individual types of access to a smgle mformation resource may have differing security requirements Nonetheless, a given level of security may be sufficient for more than one of the information services or access types For example, information resource 191 may mclude a product information service for providmg general mformation such as product descriptions or data sheets to the public, while mformation resource 192 includes an order processing system for an eCommerce site Information resource 193 may include functions for supply chain interactions such as access to inventory information or current selling price information Both the product information service and order intake functions of the eCommerce may operate with similar security requirements, e g , allowing access by minimally authenticated, non-hostile entities On the other hand, supply cham functions may require a higher level of security Order status functions of the order processmg system may require a mid-level of secunty Login component 120, operatmg m conjunction with gatekeeper/entry handler component 110 and other components of the security architecture, provides a smgle sign-on interface for access to enteφrise applications and/or resources In an exemplary embodiment, secunty requirements are expressed m terms of trust levels and logm component 120 obtains logm credentials for an entity requestmg access to one of the enteφnse applications and or resources The logm credentials obtamed are selected from a set of credential types that, if authenticated, are sufficient to achieve the trust level requirement of an application or mformation resource to be accessed Without limitation, typical logm credential types and associated authentication mechanisms mclude those based on passwords, certificates, biometric techniques, smart cards, etc Other credential types and associated authentication mechanisms are descnbed elsewhere herem In some embodiments in accordance with the present invention, gatekeeper/entry handler component 110 queries authorization component 140 to obtam authorization for access to a particular requested enteφnse application or information resource by the requestmg entity (e g , the browser user) If the entity requestmg access has not yet been authenticated to the trust level required for the particular access to the particular enteφrise application or information resource requested, authorization component 140 may indicate that the access request is to be redirected to logm component 120 so that logm credentials may be obtained and authenticated to a particular trust level If, on the other hand, login credentials have already been obtamed for the requesting entity and the requesting entity has been authenticated usmg the obtained credentials such that the required trust level has been achieved, the access will typically be allowed without the need for further logm credentials and authentication In certain circumstances, authorization component 140 may mdicate that the access is to be refused For example, authorization component 140 may be programmed to perform more stringent testing beyond a trust level requirement In an exemplary enteφrise tool configuration, a desired security policy may dictate that a salary tool is accessible only from with a company's internal network No level of authenticated trust may be sufficient to access such a tool from outside company network To facilitate implementation of such a security policy, authorization component 140 could refuse access based on environment parameters indicating a session originating outside the company's internal network Of note, m certain embodiments in accordance with the present invention, the mappmg of login credential types and authentication mechanisms to trust levels is influenced by environment information such as time of request, source of request, connection speed, and or client application (e g , browser) environment information In this way, even with a static set of mappmg rules, the set of credential types and authentication mechanisms suitable to support a given trust level may vary based on environment information In general, mapping rule dependencies are based on perceived variations in threat characteristics and/or requesting entity capabilities In some embodiments in accordance with the present invention, gatekeeper/entry handler component 110 is the authority on environment mformation for a particular requesting entity. In some embodiments, mappmg rules may be dynamically varied For example, if a particular logm credential type and/or authentication method is deemed msecure (e.g , because compromised or because of a changing threat profile), the trust level mappings can be updated and have enteφπse-wide effect. In addition, several other advantages are achieved by defining the authentication requirement interface between enteφrise applications and/or resources and the security architecture in terms of required trust levels, rather than in terms of particular credential types and authentication methods First, single sign-on configurations are facilitated usmg an enteφnse-wide credential obtammg, authentication and session tracking infrastructure Second, authentication requirements may be enforced uniformly in accordance with an enteφrise- wide secunty policy and with reduced vulnerability to a lax security implementation by any particular mformation resource. Third, credential types and authentication methods can be added, deleted, or mapped to a new trust level, all without modification of enteφrise applications and resources Of course, all advantages need not be achieved m any particular implementation. In certain embodiments m accordance with the present mvention, a credential upgrade facility is provided. In response to an access request from an entity for which login credentials have already been obtamed and authenticated, but for which the obtamed and authenticated logm credentials are insufficient for the trust level associated with the requested access, authorization component 140 may indicate that the access request is to be redirected to login component 120 so that sufficient logm credentials may be obtamed and authenticated to the required trust level. Of note, credential upgrade facilities m accordance with certain embodiments of the present invention allow upgrade without loss of session continuity. Exemplary Configuration Referring to FIG. 1, an entity (e g , a browser 170 operated by a user) interacts with enteφrise applications and/or resources (e g , 191, 192, 193) and the security architecture via a gatekeeper/entry handler component 110 and a login component 120 In general, a wide variety of entities, including human users operatmg browser and/or non-browser client applications as well as automated agents and systems, may interact with enteφrise applications and/or resources and the security architecture as descnbed herem. Furthermore, a variety of mformation resource identification schemes, such as by Uniform Resource Locator (URL), resource address, identifier or namespace designation, may be employed. However, for puφoses of illustration and not limitation, an exemplary interaction involving a browser and information resources identified by URL is described in detail Nonetheless, based on the description herein, persons of ordmary skill in the art will appreciate a wide variety of configurations in accordance with the present invention m which non-browser clients, automated agents or other systems interact with enteφrise applications and/or resources and the security architecture using any of a variety of information resource identification schemes Focusing then on an exemplary browser-type client entity, browser 170 requests access to one or more of enteφrise applications and/or resources (e g , information resource 191) by presenting an URL to gatekeeper/entry handler component 110, which acts as a point of entry for client entities requestmg access to applications and/or resources controlled by the security architecture Gatekeeper/entry handler component 110 receives the request as a proxy for the requested resource In some configurations, a combmed gatekeeper/entry handler mstance is provided, while m others, separate and/or multiple mstances are provided with functionally identical mterfaces to other components of the security architecture In some configurations, multiple instances of entry handler functionality (e g , mterception of mbound requests and collection of environment information) are provided For example, one or more mstances for each of several connection types (e g , dialup, WAN, etc ) may be employed One or more mstances of gatekeeper functionality (e g , allowing access for authorized requests and otherwise denymg or initiating appropriate responsive action) may also be provided Configurations and functional decompositions suitable to a particular environment and expected load requirements will be appreciated by persons of ordinary skill m the art Entry handler functionality (e g , in gatekeeper/entry handler component 110) ascertains much of the requesting client's environment information For example, for dial-up connections, environment mformation such as lme speed and low-level line encryption are ascertained Additional information, such as source number (e g , from caller id mformation or based on a callback configuration), signalmg type (e g , POTS or digital ISDN), etc , may also be obtained For network connections, similar environment information (e g , source network and/or node, Virtual Private Network (VPN) low-level encryption, etc ) may be obtamed from incoming requests themselves or based on a particular entry point (e g , a particular router or port) More generally, gatekeeper/entry handler component 110 obtains and or mamtams mformation such as connect location (if ascertainable), temporal mformation such as request time/date, session start time/date, etc (preferably in both the client entity's frame of reference and the secunty architecture or requested mformation resource's frame of reference, if location is ascertainable), and client type and or capabilities (e g , browser type and Java Development Kit (JDK) level) In some configurations, information on line speed, origination point (e g , inside or outside of a coφorate network), browser type, encryption capability, number of hops, latency, system type, etc may be gathered Such mformation is used in some configurations for mappmg particular authentication mechanisms to trust levels and for authorization decisions Environment mformation is generally packaged into a data structure that is associated with a client session Other components of the security architecture may add additional client environment mformation, such as authentication strength or current trust level Gatekeeper functionality (e g , m gatekeeper/entry handler component 110) checks whether a session is already associated with the incoming request Although other techniques are possible, m some configurations m accordance with the present invention, gatekeeper/entry handler component 110 checks for the presence of a session token in the incoming request Use of session tokens is described in greater detail below, however, in short, a session token may be any data supplied to the client entity for use in uniquely identifying an associated session In general, preferred session token implementations are cryptographically secured and include facilities, such as expiration or mapping to a particular connection, to limit risk of replay attack and/or spoofing Some session token implementations may encode session, principal, and/or trust level information Some session token implementations may employ cookies, URL encoding, or other similar techniques for binding to incoming requests In some configurations, session tokens are employed to facilitate session continuity and to allow the security architecture to associate prior authentication of logm credentials with an incoming access request In one utilization, session tokens are issued to client entities as part of an mteraction with the security architecture and are thereafter presented with access requests In some configurations, new session tokens (each corresponding to a smgle session) are issued to client entity on each credential level change In other configurations, a session token may remam the same even as credential levels are changed Session continuity means the mamtenance of coherent session state across one or more mteractions between an entity and an information environment Components of session state (e g , m some configurations, principal id, session id, authenticated trust level, group ids and/or roles, creation tune, expiration time, etc ) are mamtamed or advanced throughout the duration of a session Typically, aspects of session state are represented internally by the security architecture and a session token (e g , a session id encoded m a cryptographically secured session token) allows the secunty architecture to reference mto the internal representation However, m some configurations, at least some aspects of session state may be represented or duplicated m the session token For example, a prmcipal id and current trust level are encoded m one realization of a cryptographically secured session credential and associated session token or cookie In general, a variety of facilities, such as cookies, can be used to maintain state across a series of protocol interactions, such as HTTP transactions, that do not otherwise support persistent session state Refernng again to FIG. 1, if a session token is present m the incoming request, gatekeeper/entry handler component 110 resolves the token to a session object Alternatively, if no session token is present or if a session token is invalid, gatekeeper/entry handler component 110 establishes a new session (2) In an exemplary configuration m accordance with FIG. 1, session management component 160 allocates a new session and supplies associated default session credentials (2) based on the requested mformation resource and environment information Note that a session is created irrespective of authentication status or identity, although some implementations may refuse to even allocate a session based on particular mformation resource requests and/or environment information Given a session object, which may be resolved from a received session token or newly allocated, gatekeeper/entry handler component 110 mteracts (3, 4) with authorization component 140 to determine whether the requested access is authorized For some requested accesses and security policies (e g , anonymous ftp access to certain archives), even a session without authenticated logm credentials (trust level=0) may be authorized For others, a more substantial trust level may be required Gatekeeper/entry handler component 110 supplies authorization component 140 with an identifier for the requested resource (e g , the requested URL) and an identifier for the associated session Preferably, the associated session identifier is cryptographically secured (e g , as a signed session credential) In some configurations, the signed session credential is obtained from the corresponding session object In the case of a pre-existing session, the signed session credential may be obtamed using a received session token In any case, authorization component 140 receives (3) the requested resource and session identifiers and responds (4) in accordance with the trust level requirement of the requested resource In configurations for which sensitivity to a changing environment is desired, environment information may also be supplied to authoπzation component 140 In an exemplary configuration, authorization component 140 responds with an ALLOW, REDIRECT, or REFUSE response based on the sufficiency of a current trust level In some configurations, authorization component 140 dynamically calculates a current trust level based on the signed session credentials and environment mformation In others, authorization component 140 may base its ALLOW, REDIRECT, or REFUSE response on a "current" trust level previously associated with the signed session credentials Generally, an access request with sufficient current trust level is ALLOWED and forwarded (14) without further authentication An authorization request without proper parameters (e g , without a specified information resource or without a properly secured session credential) may be REFUSED Authorization requests associated with a client entity that has been blacklisted or for a resource for which the associated client entity cannot be authenticated using any available method to achieve the required trust level may also be REFUSED For example, a given security policy and associated trust level mappings may dictate a REFUSE response in response to an access request to a sensitive resource (such as financial data) by any client entity (even a browser supplying the digital certificate for the CFO, and therefore presumably operating on behalf of the CEO) if the access request is received over a dial-up line and oπgmates from an unknown number or is received outside of working hours In general, there is an implicit, base level of environment inherent m an authenticated trust level, however, in some configurations, a particular authorization transaction may dig deeper mto environment information before respondmg For example, in configurations providing log-up capabilities, an authorization service will typically redirect to a logm service if the trust level associated with current session credentials is msufficient for a requested access However, for sensitive applications m such a configuration, an madequate trust level may result m a REFUSED message rather than a log-up REDIRECT dependmg on the particular secunty policy implemented A REDIRECT response is used to forward the access request to login component 120 so that sufficient logm credentials may be obtained and authenticated to achieve the required trust level for the requested access Note that in some configurations, both initial login credentialmg and credential upgrade are provided using the REDIRECT facility In response to a REDIRECT response (4), gatekeeper/entry handler component 110 redirects (5) browser 170 to login component 120 In one configuration, gatekeeper/entry handler component 110 issues a client-side redirect via HTTP location directive to forward the request to logm component 120 Parameters such as required trust level, requested URL and credential passmg method can be encoded in the redirect URL and supplied (6) by browser 170 to logm component 120 Alternatively, some parameters can be passed (5A) directly (e g , through a HttpSession object) although a stateless configuration is preferred A session token is passed to browser 170 in conjunction with the redirect (5) to login component 120 Based on the description herein, persons of ordinary skill m the art will appreciate a number of suitable mechanisms for passing the session token, including those based on cookies and URL encoding Preferably, mechanisms employed are based on facilities provided by commercially available browsers (e g , in accordance with HTML 3 x, 4 x or other de-facto standards), although customized or plug-in facilities for receiving and supplying session token may be employed In one suitable configuration, the session token is cryptographically secured and encoded in a cookie placed at browser 170 usmg a set cookie directive embedded in the redirect. Other configurations may use a less persistent session identification method, such as passmg an identifier or session token m the redirect URL without storage at browser 170. Still other configurations may transmit a session token, a session credential, or identifier such as a session handle for storage in a medium such as a smart card In configurations providmg credential upgrade, persistent session identification methods are generally prefened, even for a not yet authenticated client entity, for consistency of approach Note that although the identity of the client entity may not be authenticated to a sufficient level of trust, the redirected request includes a session token that at least identifies the session Other configurations may omit the binding of session tokens to sessions of not yet authenticated client entities, though with some increase in complexity of login component 120. Browser 170 sends (6) logm component 120 a new access request usmg the URL specified m the redirect from gatekeeper/entry handler component 110 In configurations employmg cookies as a medium for passing session tokens, the new access request will include the cookie and therefore the session token. Note that m configurations in which the security architecture controls access to resources m several domams, care should be exercised to select a tag or tags for the cookie such that it will be provided through normal operation of the browser m subsequent accesses to any of the several domams. Persons of ordmary skill in the art will appreciate suitable taggmg techniques, including the use of multiple cookies Logm component 120 receives the access request and determines an appropriate authentication scheme based on mappmg rules that identify those authentication schemes which are sufficient to achieve a given trust level. Preferably, the mappmg rules are a function of environment information In some configurations, mappmg rules are implemented as fuzzy sets wherem acceptable authentication schemes are a function of required trust level and environment information In this way, environment affects the set of authentication schemes sufficient to meet a trust level requirement. Generally, mapping rule logic is evaluated before a user is challenged to authenticate Mappmg occurs as a function of session environment and particulars of the mformation resource for which access is requested By evaluatmg the minimum trust level required by the target of an access request, a service (e.g., a login service such as provided by logm component 120) derives a list of potential authentication methods. The service then checks current session environment agamst the allowed environment states for each potential authentication method to trim the list further If there is no particular resource for which access is bemg requested (e.g , if a user jumps straight to a sign-on page without requesting an access), the service will proceed according to the lowest level of trust available consistent with session environment Other configurations may employ differing default behaviors In some configurations, logm component 120 queries (7) authorization component 140 to identify the set of authentication schemes that meet or exceed the required trust level given a cunent environment. In other configurations, the mapping is performed by login component 120 In either case, login component 120 supplies (9) information to browser 170 to allow the user to select from the suitable authentication schemes and to provide an associated logm credential In some configurations, login component 120 supplies browser 170 with a logm page (e g , HTML) that prompts the user for an application specific user ID and a choice of authentication schemes Interactions with browser 170 depend on the set of credential types that, if authenticated, would be sufficient to meet the trust level requirement for access to the requested resource For example, if more than one type of credential would be sufficient, login component 120 may interactively allow a user to select from amongst the credential types (e g , usmg any HTML-based dialog) Once a particular credential type has been selected, logm component 120 interacts with browser 170 to obtam an mstance of the logm credential to establish the identity of the browser user Some credential types (e g , username/password parrs, onetime passwords, enigma challenge, etc) may be obtained through an interactive process in which the user supplies the login credentιal(s) entry mto an HTML form browser 170 POSTs form contents back to login component 120 Others (e g , digital certificates) may be supplied (10) for the client entity from browser 170, or in some configurations, may be obtamed from or via an agent or certificate authonty A personal digital certificate (such as those issued by Vensign™, Thwate, Entrust or other certificate authority) may be obtained from a browser 170 usmg an HTTP certificate request Although credentials may be transacted in a vanety of ways, credentials are typically obtamed from a user Typically, the obtammg is indirect by askmg the user's browser to complete the negotiation process In such configurations, certificate-based authentication may be transparent to the user In some configurations, further authentication can be performed by using information encoded within the certificate to query a certificate authority for current status or a lookup to an authentication database may be performed for more detailed requirements In an exemplary configuration, the more detailed information could relate to session environment or could force an additional name/password authentication as part of the certificate authentication cham In a particular implementation such facilities can be provided by mappmg rule encodmgs that require successful authentication usmg multiple authentication methods to achieve a given trust level Once login credentials have been obtained by login component 120, they are supplied (11) to gatekeeper/entry handler component 110 for authentication In configurations in which both gatekeeper/entry handler component 110 and logm component 120 have access to a shared object such as the HttpSession object, logm credential passmg via the shared object is suitable In other configurations, an HTTP POST may be employed In an exemplary configuration, the particular credential passing method is selected as part of the original HTTP redirect (e g , encoded m the redirect URL) although other configurations need not allow for a selection or may employ other facilities for selection of a credential passing method Login component 120 also passes control of the access request back to gatekeeper/entry handler component 110 In an exemplary configuration, login component 120 issues a new HTTP request (11) specifying the originally requested URL, which has been stored in the HttpSession object As before, gatekeeper/entry handler component 110 receives the request Gatekeeper/entry handler component 110 extracts the login credentials from the request or from the HttpSession object and passes (12) the login credentials to authentication component 130 for authentication Authentication component 130 authenticates the login credential, and if successful, queries (13) identification component 150 to establish a correspondence with a set of entity descriptors that uniquely identifies the requestmg entity In an exemplary configuration, entity descriptor types mclude entity id, system id (e g , name/password), certificate, enigma id, smartcard token, name/address, and phone One or more of values may uniquely identify an entity and one or more entity descriptor types may support multiple values (e g , multiple digital certificates, name/password pairs, or phone numbers per identity) Once the requesting entity has been identified (14), session parameters are updated (15) and session management component 160 supplies (16) session credentials Preferably, session credentials are digitally-signed or otherwise cryptographically secured and returned (17) to gatekeeper/entry handler component 110 Gatekeeper/entry handler component 110 again supplies (18) authorization component 140 with an identifier for the requested resource (e g , the requested URL) and an identifier for the associated session (e g , the signed session credentials authorization component 140 responds with an ALLOW, REDIRECT, or REFUSE response based on the sufficiency the session credentials (and underlying authentication of logm credentials) for the trust level required for the requested access Login credentials should now be sufficient for access to the requested resource and an ALLOW response is supplied (19) by authorization component 140 Gatekeeper/entry handler component 110 proxies the requested access (20, 21) to mformation resource 191 and streams (22) results back to login component 120 Logm component 120, m turn, streams (23) results back to browser 170 In some embodiments in accordance with the present invention, session continuity is facilitated by supplymg a session token to browser 170 For example in one configuration, login component 120 supplies a session token usmg a set cookie directive encoded with the results streamed (23) back to browser 170 In response, browser 170 stores the cookie using a tag (typically a filename encoding) Browser 170 supplies the cookie (and the session token) with subsequent access requests based on a correspondence between the tag and the requested resource Typically, the correspondence is based on the second-level domam (e g , sun com) m which the requested resource is hosted, although nth-level domams or other resource identification and session token associatmg schemes may be employed In configurations m which the security architecture controls access to multiple domams across which a spanning smgle sign-on is desired, multiple cookies may be employed Although the encodmg of session tokens usmg cookies is presently preferred, m part because cookie facilities are widely supported and reasonably well accepted, other facilities may be employed to establish session continuity For example, alternative URL encodmgs and/or custom or plug-in support for session identifier receipt, storage and supply may be employed Also, some configurations may employ lower-level session identifiers, e g , as provided by a particular connection type such as trusted caller id mformation or as associated with a low-level line encryption or virtual private network infrastructure As such facilities are likely to be connection-type specific, it is envisioned that they may be used m conjunction with other session identifier facilities described above, e g , session tokens encoded in cookies In one configuration, the unique Ethernet MAC address associated with a network mterface card may be employed as a session handle The MAC address is then used to associate with a particular set of session credentials maintained by a central authority In general the representation of a session handle can take may forms Referring again to FIG. 1, subsequent access requests (e g , access request 1A) mclude a previously assigned session token As described above, gatekeeper/entry handler component 110 uses the session token, lf provided to resolve a session object containing session credentials, and to determine whether previously authenticated credentials are sufficient for the requested access As described above, authorization component 140 may be queried usmg session credentials and an identifier for the requested resource to determine sufficiency of previously authenticated credentials In some configurations, sufficiency is determined usmg trust level mappings as described above Dependmg on the information resource to which access is requested, and in some configurations depending on current session environment information, access request 1A may or may not have associated previously authenticated credentials sufficient to support the requested access In the case of an access request 1 A having a trust level requirement commensurate with previously obtamed and authenticated credentials (l e , an access request for which no additional credentials need be obtamed via login component 120), the access request is proxied (20) and results (21) are streamed directly (23A) back to browser 170 In some configurations, gatekeeper/entry handler component 110 supplies an updated session token usmg a set cookie directive encoded with the results streamed (23A) back to browser 170 An updated session token, if supplied, resolves to the same session object as the session token replaced For example, m some configurations, both session tokens encode a same session handle, although other aspects associated with session token secunty such as expiration may be updated In other configurations, results (21) are streamed (23 A) back to browser 170 without an updated session token In such configurations, the previously supplied session token remams valid until expired or otherwise invalidated Some variations may employ a session token refresh interval Depending on the mformation resource to which access is requested, previously obtamed and authenticated logm credentials may be msufficient for the trust level requirement associated with requested access 1A As before, authoπzation component 140 supplies gatekeeper/entry handler component 110 with an ALLOW, REDIRECT or REFUSE response based on the trust level accorded based on the previously obtamed and authenticated logm credentials and on the trust level requirement associated with requested access 1A Advantageously, authorization of individual access requests is streamlined by the encoding of trust level in a cryptographically secured session credential or token In the case of msufficient credentials, a REDIRECT response is supplied and gatekeeper/entry handler component 110 agam redirects (5) browser 170 to login component 120 Additional logm credentials are obtamed as described above with reference to initial credentials Upon successful authentication, access request is proxied (20) and results (21) are streamed (23 A) back to browser 170 Preferably, gatekeeper/entry handler component 110 supplies an updated session token usmg a set cookie directive encoded with the results streamed (23A) back to browser 170 An updated session token, if supplied, resolves to the same session object as the session token replaced As a result, session state (including e g , identity mappmgs, authorizations, roles, permissions, environmental variables, etc ) is maintained through the credential level change However, in the case of a credential upgrade, the session object now encodes a login credential successfully authenticated to achieve a higher trust level In one advantageous configuration, the achieved (higher) trust level is encoded m a cryptographically secured session token representation as a cookie streamed (23 A) back to browser 170 with results (21) FIG. 2 illustrates operation of an exemplary security architecture providmg a smgle sign-on facility with trust level mappmg to authentication requirements As before, an access request is received (201) from a client entity If the request does not contam a session identifier (e g , a session key or token) or if the request can otherwise be reliably associated with a session mamtamed by the security architecture, a new session is created (202) A trust level requirement is determmed for access to the requested resource m the context of the requesting session environment In some configurations, as described above, the determmation is performed by an authonzation service such as authorization component 140 Given a trust level requirement, current session credentials are evaluated (203) m the context of session environment mformation to determine whether the previously supplied login credentials are sufficient to achieve the required trust level In one advantageous realization of session credentials and tokens, a cryptographically secured encoding of trust level allows authorization to be confirmed without mvolvement of an authentication service (e g , with reauthentication of login credentials) In the case of a newly created (202) session, the authorization evidenced by session credentials will typically be insufficient, although some security policies may allow anonymous access to certain resources For a pre-existmg session, I e , for an access request that can be reliably associated with a persistent session by a cryptographically secured session token or otherwise, session credentials may or may not be sufficient for access to the currently requested resource For example, after a first access, the identity of an entity accessmg resources controlled by the security architecture will be authenticated to a trust level sufficient for that access Dependmg on the trust level requirements of a subsequent access and, m some configurations, dependmg on then current trust level mappmg rules and environment mformation, the level of trust associated with a current session (e g , as evidenced by current session credentials) may or may not be sufficient for the subsequent access In situations for which a current level of trust (e g , resultmg from prior authentication of login credentials for an entity associated with the session) is sufficient for later access to the same or to another mformation resource, access is allowed without additional authentication For example, in some secunty architectures in accordance with the present invention, the security architecture proxies (204) the request to the requested information resource and streams (205) a resulting response back to the requesting client entity As described elsewhere herein, sufficiency of current session credentials is determined using mappmg rules that, in some realizations, mclude environment mformation In general, current session credentials may be insufficient (1) because the identity of the requestmg client has not yet been authenticated (e g , m a first access situation), (2) because of a higher trust level requirement for the requested access, or (3) because of a change in mappmg rules or environment that causes a previously sufficient credential no longer be sufficient for a particular trust level Whatever the reason for the insufficiency, a request corresponding to a session and client entity that is insufficiently authenticated, and that is therefore not authorized, is passed to a facility for obtammg credentials of a type that, if authenticated, will support the required trust level Typically, session credentials and or an associated session token encode an expiration time (see description, below, of FIG. 4) In such configurations, a previously sufficient session credential is insufficient after its expiration In some configurations, session credentials are periodically refreshed by reauthentication of the underlying login credentials For example, in one implementation, a presented session token indicating expiration in less than five (5) minutes causes the security architecture to reauthenticate (not shown) underlymg login credentials stored m a conespondmg SessionObject (e g , under the pnvate key of authentication component 130) Reauthentication typically results in a new session credential and associated trust level Dependmg on then instant mappmg rules, the associated trust level may or may not be sufficient Also, reauthentication may fail if the login credentials have been invalidated, revoked or if the logm credentials have expired Assuming that reauthentication of login credentials is successful, updated session credentials are issued, for example, by authentication component 130 and supplied (e g , as a cookie encoded session token) to the client entity e g , browser 170) Referring again to FIG. 2, a request corresponding to a session not authorized for a requested access is redirected (206) to a credential gathermg service (e g , login component 120) The credential gathering service receives (207) the redirected access and obtams (208) a trust level requirement for the requested access In some configurations, the trust level requirement may be passed with the redirected access or otherwise associated with the redirected access, in others the trust level requirement may be re-obtarned from an authorization service such as authorization component 140 A trust level requirement is mapped (209) to at least one authentication scheme sufficient to achieve the requirement based on current trust level mappmgs and, if employed m the mapping rules, based on current environment mformation Assuming that at least one authentication scheme is available that, if successful, will support the required trust level, logm credentials of that type are obtained (210) for the entity and authenticated (211) Some credential types (e g , username/password pairs, onetime passwords, enigma challenge, etc) may be obtamed through an interactive process m which a prmcipal (e g , a human user) supplies the credentιal(s) entry m an HTML form and POSTs form contents back to the credential gathermg service Others (e g , certificates) may be obtamed for the client entity from an agent or authority For example, a personal digital certificate (such as those issued by Verisign™, Thwate, Entrust or other certificate authority) may be obtamed from a browser using an HTTP certificate request In some configurations, a choice of credential types may be provided and user may select from a set of credential types sufficient for the requested access Once appropriate logm credentials have been obtamed and authenticated, the session corresponding to the requested access is updated (213) to reflect the new authenticated session credentials The now sufficiently authorized request is proxied (204) and results are streamed back (205) to the requestmg client entity Updated or refreshed session credentials are typically supplied as a session token (e g , a cookie) encoded with the streamed results FIG. 3 illustrates mteractions between functional components in an exemplary functional decomposition of a security architecture An on-line order processing transaction is exemplary and functional boundaries are merely illustrative Based on the description herem, a wide variety of suitable enteφrise information environments and functional decompositions m accordance with the appended claims will be appreciated by persons of ordmary skill in the art In the configuration of FIG. 3, application and central security portions (321 and 322, respectively) of the security architecture are illustrated Of note, functional components of application security portion 321 are typically hosed as services on a first server environment, while functional components of central security portion 322 are hosted as services on a second server environment In this way, most interactions amongst functional components occur withm a single server environment and do not require network transactions. In the configuration of FIG. 3, credentials associated with a calling component (e.g , framework credentials associated with application security framework 303 or application credentials associated with order management service 312) are used to establish sufficient authorization for network transactions Other configurations may be employed, however, the relatively small number of network transactions (e.g., authentication transaction 331 and optional value passing transaction 332) tends to improve performance of the security architecture Of note, authentication transaction 331 need only be performed on login credential authentication (e.g., at initial sign-on or credential upgrade) or reaufhenticated (e.g., to refresh session credentials). Value passing transaction 332 provides an optional facility for passing values amongst multiple components of a distributed application (e.g., a distributed implementation of order management service 312) wherein application credentials are used to mediate storage and retrieval of values m a central registry. User 301 mteracts with browser 302 to place an order with order management service 312. An application security framework 303 receives an access request mcludmg the order and, operatmg m conjunction with a variety of other services, provides a single sign-on facility substantially as described above If the order does not mclude a session token or cannot be otherwise associated with corresponding valid session credentials, then session credentials are obtamed As illustrated m FIG. 3, session credentials are obtamed usmg logm credentials (e.g., a username/password parr, a digital certificate, etc ) Typically, an access request without session credentials will not have associated login credentials As a result, and default login credentials (e g., ιdentιty=anonymous) are used during initial phases of a smgle sign-on process Nonetheless, in some configurations, logm credentials may be provided with an initial access request. More typically, an initial access request is received by application security framework 303 without session credentials or without prior presentation and authentication of logm credentials sufficient to access the requested resource. In response to credential gathermg operations, a subsequent request is made with logm credentials that p port to be sufficient, if authenticated, to meet the trust level required for access to order management service 312. In such a case, session credentials are obtained by passing login credentials to a central security framework 304 Authorization of application security framework 303 for access to components of the central secunty portion 322 is checked by query to central authorization service 306 Assuming that framework credentials evidence sufficient authorization, logm credentials are authenticated by central authentication service 307 Central authentication service 307, m turn, mteracts with central prmcipal registry 310 to establish the identity and group membership of user 301 and with central session registry 311 to create a persistent session for subsequent accesses by user 301 Particulars of the request are logged to central audit service 308 and, if authentication was successful, session credentials are returned to application security framework 303 Signed session credentials are presented to application authorization service 313 together with an identifier for the requested resource and optionally with an identifier for a particular function or facility of the requested resource In response, application authorization service 313 checks the authorization of the prmcipal (e g , of user 301) associated with the session credentials to access the requested resource Application authorization service 313 interacts with application resource registry 314 to identify trust level requirements for the requested resource (and in some configurations, for a particular function or facility of the requested resource) and determines the sufficiency of a current trust level evidenced by the session credential Note that trust level is assessed by inspection of the session credential and without interaction with an authentication service In some configurations (e g , as illustrated in FIG. 3), group membership is also evaluated as part of the authonzation check If the signed session credentials indicate that the requesting entity, e g , browser 302 on behalf of user 301, is sufficiently authorized to access order management service 312, a CreateOrder request is passed to order management service 312 and order processing proceeds in accordance with normal handling thereof Additional accesses may be required, e g , to select delivery options or to confirm some aspect of the order Assuming that the additional accesses do not require a higher trust level, they will be passed to order management service 312 based on the correspondence of session credentials with trust level requirements If an exception is thrown due to msufficient authonzation, e g , if the signed session credentials do not mdicate that the requestmg entity is sufficiently authorized to access order management service 312, a login credential gathering process is initiated Based on the required trust level and on rules that encode the sufficiency of authentication schemes, a logm credential is obtamed from user 301 and/or browser 302 The obtamed logm credential is of a type that, if authenticated, is sufficient to meet the trust level requirement for access to order management service 312 Aspects of an exemplary credential gathering process are described m greater detail above However, as an example, FIG. 3 illustrates the obtaining of a username/password pan- Once logm credentials are obtamed, they are passed to central security framework 304 (as described above) for authentication by central authentication service 307 so that session credentials can be obtamed, the requested access can be authonzed, and the order processmg mitiated Signed session credentials, typically embodied as a cryptographically secured session token that may be stored as a cookie, are passed back to browser 302 with results of the requested access In this way, subsequent access requests are identified as part of a session and authonzation may be quickly confirmed without unnecessary re-aufhentication Some configurations in accordance with the present invention employ session credentials as a mechanism for evidencmg prior authentication of obtained login credentials and for bindmg individual transactions to a particular session In some configurations, session credentials are also employed m a session token form advantageous for transactions external to the security architecture In an exemplary realization, session tokens are encoded for supply to browsers as cookies FIG. 4 illustrates relationships between exemplary login credential, session credential and session token objects As described above, logm credentials (e g , represented m a form such as exemplary logm credentials structure 410) are obtained for a client entity Typically, login credentials encoded in logm credentials structure 410 are obtained from a principal via browser client and serve as evidence that the principal (e g , a human user) is entitled to a particular identity Accordingly, login credentials structure 410 encodes a userld and a domainld within which the userld should uniquely correspond to a prmcipal Specific logm credentials, e g , a password, a certificate, results of a biometric process, a response to an Enigma challenge or results of a smart card interrogation, etc are encoded in login credentials structure 410, as a tagged value An authenticationScheme is specified and creation time may be encoded to limit replay attacks In the lmplementation of FIG. 4, logm credentials strucmre 410 is encrypted usmg the public key of an authentication service (e.g., of authentication component 130). Because the key is public, any component, even untrusted components may encrypt login credentials for provision to authentication component 130, while only authentication component can decrypt the encrypted login credentials using its private key. In some configurations, secure transfer protocols, e.g., SSL, are employed to secure logm credentials between a client entity such as browser 170 and the security architecture while encryption with a public key of an authentication service is performed within the security architecture, e.g., at logm component 120. In other configurations, encryption with a public key of an authentication service may be performed at the client entity. If the encrypted login credentials provided to an authentication service are determined to be authentic, session credentials are issued In the implementation of FIG. 4, session credentials are embodied m a form such as exemplary session credentials structure 420. Encrypted and clear text portions (421 and 422) of session credentials strucmre 420 allow contents of the session credential to be read by anyone and changed by no one (except the authentication service possessing a pπvate key) Contents of encrypted portion 421 correspond to that clear text portion 422 but are encrypted using the pnvate key of the authentication service (e g , of authentication component 130) Of note, prmcipal ids, authorizations and other contents encoded in the session credential may be read by components of the security architecture, and m some embodiments by components external to the security architecture. Such components can verify the authenticity of mformation stored m clear text portion 422 using encrypted portion 421 and a public key corresponding to the pnvate key of the authentication service Of note, the mformation contained in a session credential is generally not sensitive. What is sensitive is the state of the mformation. Therefore, secunty architectures employmg facilities described herem ensure that mformation contained m the session credential is provably constant once set by an authentication service By usmg the public key of the authentication service, which will m general be freely available, together with the encrypted mformation, any application can read the mformation (e.g., m free text) and ascertain that the session credential was created by the authentication service and that the session credential has not been tampered with Assuming that the authentication service's private key has not been compromised, tampering with the session credential will result in a decryption failure. In an alternative implementation (not shown), session credentials may be digitally signed and verified by a public key corresponding to a pπvate key In such an alternative implementation, the digital signature also allows contents of the session credential to be read by anyone and changed by no one For some configurations, the implementation of FIG. 4 is preferred because encrypted portion 421 can be used as an externally supplied session token Such a session token representation is a compact representation of the session credential particularly appropriate for encoding as a cookie placed at a browser and returned with subsequent access requests Referring agam to session credentials structure 420, a session id, a prmcipal id, a trust level, group ids, a creation time and an expiration time are encoded in both m encrypted portion 421 and clear text portion 422 The session id is a unique identifier for a persistent session maintained by the security architecture. In implementations in which credential upgrade is provided or in which a session credential expiration and refresh is provided, multiple successively issued session credential instances may encode the same session id and correspond to the same persistent session Prmcipal id encodes an identifier for a prmcipal to which the security architecture has resolved logm credentials. For example, a login credential including a usernamejdoe and a password corresponding to jdoe may be resolved by the security architecture to a unique prmcipal id associated with John. Q Doe of the shipping and receivmg department, having an employee badge number of 12345, etc. In some embodiments, a trust level encodes the authorization level to which a principal has been authenticated. In such embodiments, the encoded trust level serves as a basis for evaluating whether a principal associated with the session credentials has been authenticated to a sufficient level for access to a requested resource For example, a trust level of 5 may be sufficient for access to information resources having a trust level requirement of 5 or less Trust levels offer an attractive decouplmg of authonzation levels and authentication methods as described elsewhere herein However, m some embodiments, an authonzation encoding may establish that a prmcipal has been authenticated usmg a particular authentication mechanism. In either case, an authorization (e.g., encoded as a trust level) m a cryptographically secured session credential allows the security architecture to authorize accesses based on prior authentication of a login credential and without involvement of the authentication service Group ids can be used to grant or limit authorization scope based on group membership Typically, session credentials serve as evidence of prior authentication and authorization for multiple accesses to information resources controlled by the security architecture. However, session credentials may be replaced on a logm credential upgrade as described elsewhere herem. In addition, session credentials of limited temporal validity may be refreshed by penodic replacement In the configuration of session credentials structure 420, creation time and expiration tune allow the security architecture to improve resistance to replay attacks Session credentials typically have a relatively short expiration time (e.g., 15 minutes from creation or less) and underlying login credentials will be reauthenticated prior to expiration of the session credential. Assuming that the underlying logm credentials, which are stored under the public key of authentication component 130, remain valid, authentication component 130 will issue a replacement cryptographically secured session credential (e g., as session credentials structure 420). Dependmg on then current trust level mappmgs and, in some configurations, depending on then current environment parameters, the authorization accorded by the security architecture and encoded as a trust level may differ from that encoded m the session credential replaced If a prmcipal id or login credential has been revoked, reauthentication may fail and a user may be prompted to supply a sufficient login credentials as described elsewhere herein. Session id and principal id will typically remain the same for successive session credentials associated with a smgle persistent session As previously described, one advantage of the approach employed m session credentials strucmre 420 is that encrypted portion 421 may also be employed as a compact session token representation 430 of session credential for use as a cookie In one embodiment m accordance with FIG. 4, encrypted portion 421 is a strmg encoded representation of approximately 200 characters which may be placed at a browser (e g , via transfer 5, 23 or 23A of FIG. 1) using a set cookie directive Exemplarv Implementations In an exemplary embodiment, at least some of the above-described components are implemented as servlets executable in the context of a commercially-available web server environment For example, the Java™ Embedded Server (JES) architecture with extensions for certificate handlmg, HyperText Transfer Protocol (HTTP), Simple Network Management Protocol (SNMP), Secure Sockets Layer (SSL), extensible Markup Language (XML) grammar processmg and security Access Control List (ACL) support available from Sun Microsystems, Inc is one suitable environment Java and all Java-based marks and logos are trademarks or registered trademarks of Sun Microsystems, Inc in the United States and other countries In general, the description herem is focused on aspects of a security architecture, rather than on peculiarities of a particular implementation environment It is envisioned that security architectures m accordance with the teachmgs of the present mvention may be implemented m the context of many commercially-available networked mformation service environments, mcludmg web server environments, as well as m custom environments and environments that m the future will be developed However, to facilitate an understandmg of broad concepts using a specific exemplary environment, and without limitation, the descnption herem may mclude terminology specific to the Java Embedded Server (JES) architecture Nonetheless, based on this description, persons of ordinary skill in the art will appreciate implementations suitable for other environments The scope of the invention, as defined by the claims that follow, is not limited to any specific implementation environment While the invention has been described with reference to various embodiments, it will be understood that these embodiments are illustrative and that the scope of the mvention is not limited to them Many variations, modifications, additions, and improvements are possible For example, the set of authentication schemes described herein is illustrative and embodiments in accordance with the present invention may include others, mcludmg those that may be hereafter developed If employed, rules mapping trust levels to authentication schemes may be encoded in a variety of ways depending on the particular implementation In general, such mappmg rules may be encoded as static or dynamic table associating trust level to authentication schemes Alternatively, mappmg rules may be encoded as predicates or in other declarative forms Mappmg rules may be encoded m a weighted logic or fuzzy set form Additionally, particular mappmgs may depend environment information Furthermore, evaluation of mappmg rules may be performed m a variety of functional components such as an authonzation service, a credential gathermg service or a gatekeeper Session continuity may be provided using cryptographically secure session tokens passed as cookies or by other mechanisms In some configurations, a session token is a compact encrypted representation of at least selected contents of a session credential Other compact representations corresponding to a session credential may be employed Alternatively, the same representation of session credentials may be employed both withm the security architecture and outside the security architecture (e g , at a browser or other client) Suitable contents of a session credential (and session token, if employed) will be appreciated by persons of ordmary skill m the art based on the description herein of specific examples More generally, plural instances may be provided for components described herem as a smgle instance Finally, boundaries between vanous components, services, servlets, registries and frameworks are somewhat arbitrary, and particular operations are illustrated in the context of specific illustrative configurations Other allocations of functionality are envisioned and may fall within the scope of claims that follow Strucmres and functionality presented as discrete components in the exemplary embodiment s) may be implemented as a combmed strucmre or component These and other vanations, modifications, additions, and improvements may fall with the scope of the mvention as defined m the claims that follow

Claims: WHAT IS CLAIMED: 1. An information secunty system comprising: plural mformation resources distnbuted amongst and executable on one or more servers coupled via a communication network to a client entity, the plural mformation resources havmg associated trust level requirements, a gatekeeper inteφosed between the client entity and the information resources; and a credential gathering service common to the plural mformation resources, wherein upon receipt of a first request for access to a first of the plural information resources without prior authentication to a sufficient trust level, the gatekeeper redirects the first request to the common credential gathermg service and the common credential gathenng service obtams a logm credential for the client entity m accordance with a mapping rule establishmg a correspondence between the sufficient trust level and a set of suitable credential types 2 An information security system, as recited m claim 1, wherein the first request without prior authentication includes an initial request for access to the first information resource. 3 An information security system, as recited m claim 1, wherem the first request without prior authentication mcludes a subsequent request for access to the first mformation resource, the subsequent request for access requmng a higher trust level than an initial access request. 4. An information secunty system, as recited m claim 1, wherem upon receipt of a second request for access to a second of the plural information resources, the second request is serviced without redirection to the credential gathering service, the second information resource having a trust level requirement no greater than that of the first mformation resource. 5. An information security system, as recited m claim 1, wherem the correspondence established by the mappmg rule is a function of session environment mformation 6 An mformation security system, as recited in claim 5, wherem the session environment mformation mcludes one or more of connection speed, source domam, HTTP environment mformation, browser type, authentication type, request method, MIME typing, user agent, referrer identity, date and time 7 A credential gathermg service providmg a single sign-on for sessions that potentially mclude access to plural information resources having differing security requirements, the credential gathering service comprising an input port configured to receive an access request identifying an mitiatmg client entity, means for associatmg a trust level requirement with the access request, an encoding of correspondence between trust levels and credential types, selection logic for selectmg m accordance with the encodmg, a credential type corresponding to the trust level requirement, and a credential obtammg interface for requestmg and receivmg a credential of the selected credential type for the initiating client entity 8 A credential gathermg service as m claim 7, wherem the credential obtaining mterface is with the initiating client entity 9 A credential gathermg service as in claim 7, wherem the credential obtammg interface is with a credentialmg authonty 10 A credential gathering service as in claim 7, wherem the credential obtammg mterface is with a credentialmg device selected from the set of retmal scan device, a voicepπnt analysis device, a fingeφnnt analysis device, and a card reader 11 A credential gathering service as in claim 7, further compπsmg an authentication mterface for authenticatmg the received credential 12 A credential gathermg service as in claim 11 , wherem the authentication interface includes a communications mterface to an authentication service with one or more pluggable authentication modules corresponding to the credential types 13 A credential gathenng service as in claim 7, wherem the initiating client entity is not initially authenticated to a trust level required by a first of the information resources, and wherein an attempted access to the first information resource by the initiating client entity is redirected to the credential gathering service with an associated trust level requirement corresponding to that required by the first mformation resource 14 A credential gathermg service as in claim 13, wherein the initiating client entity m not initially authenticated 15 A credential gathering service as m claim 7, wherem the log-on request and associated trust level requirement are supplied by the mitiatmg client entity 16 A credential gathering service as m claim 7, wherem the trust level requirement is supplied by the initiating client entity 17 A credential gathenng service as in claim 7, wherem the mitiatmg client entity is one of an application and a user 18 A credential gathermg service as m claim 7, wherem the credential types include at least two of passwords, certificates, username/password pairs, one time passwords, biometnc indicia, and smart cards 19 A credential gathermg service as m claim 7, wherem more than one credential type corresponds to a given trust level 20 A credential gathering service as in claim 7, wherem the correspondence between trust levels and credential types is dynamic and the encodmg thereof is updateable 21 A credential gathering service as m claim 7, wherem the set of credential types and corresponding trust levels is dynamic and the encodmg thereof is updateable 22 The credential gathermg service of claim 7, encoded m a machme readable medium as software executable m a networked computmg environment to provide the plural mformation resources with the smgle sign-on 23 The credential gathermg service of claim 22, wherem the machme readable medium is selected from the set of a disk, tape or other magnetic, optical, or electronic storage medium and a network, wired, wireless or other communications medium 24 A method of providmg a smgle sign-on for plural information resources, the method comprising associating credential types with trust levels, specifying for each information resource, required ones of the trust levels for accesses thereto, obtaining at least one credential corresponding to a client entity and authenticating the client entity thereby, and perrmttmg access to any of the mformation resources havmg a specified trust level requirement commensurate with the trust level associated with the authenticated at least one credential 25 A method, as recited m claim 36, further compnsmg denying access to any of the information resources havmg a specified trust level requirement greater than with the trust level associated with the authenticated at least one credential 26 A method, as recited in claim 36, further comprising for access to any of the information resources havmg a specified trust level requirement greater than the trust level associated with the authenticated at least one credential, obtaining at least one additional credential corresponding to a client entity and authenticatmg the client entity thereby, the at least one additional credential havmg an associated trust level commensurate with specified trust level requirement 27 A method, as recited m claim 36, wherem the credentials types mclude at least two of passwords, certificates, username/password pairs, one time passwords, biometric indicia, and smart cards 28 A method of providmg sign-on m a networked mformation environment, the method compnsmg directing a request for access to a first mformation resource from an msufficiently authenticated client entity to a credential gathenng service, associating a first trust level requirement with the access to the first mformation resource, selectmg from plural credential types, a credential type havmg an associated trust level commensurate with the first trust level requirement, obtammg a credential of the selected credential type for the client entity, and authenticating the obtained credential 29 A method, as recited m claim 28, the method further compnsmg proxymg the access request upon successful completion of the authenticatmg 30 A method, as recited m claim 28, the method further compnsmg supplymg a cryptographically secured session token to the client entity based on the authenticated credential 31 A method, as recited in claim 28, the method further compnsmg after successful completion of the authenticating, proxying a second access request without additional authentication 32 A method, as recited in claim 31 , wherein the second access request is directed to the first information resource. 33. A method, as recited m claim 31, wherem the second access request is directed to a second information resource, a second trust level requirement associated with access thereto being no greater than the first trust level requirement 34. A method, as recited in claim 28, wherem the associatmg is by a mappmg rule encoded as one or more of a static or dynamic table, a hierarchy of predicates, weighted logic and fuzzy sets 35. A method, as recited m claim 28, wherem the associatmg is a function of at least resource identifier and environment information 36 A method of providmg a security interface common to plural information resources, the method compnsmg: associatmg credential types with trust levels, specifying for each information resource, a required one of the trust levels for accesses thereto; with a logm service common to the plural information resources, obtammg at least one credential corresponding to a client entity and authenticatmg an identity of the client entity thereby; grantmg or denying access to a first of the mformation resources based on correspondence between the required trust-level therefor and an authenticated trust level associated with the obtamed at least one credential; and granting or denying access to a second of the information resources based on correspondence between the required trust-level therefor and the authenticated trust level 37 A method, as recited m claim 36, wherem the at least one credential is selected from a set of credential types with associated authentication modules 38 A method, as recited m claim 36, wherem differing trust levels are required for access to the first and second information resources.

Inventors: FERRIS CHRIS, NORTON DERK, WESCHLER PAUL, WILSON YVONNE, WOOD DAVID L, FERRIS, CHRIS, NORTON, DERK, WESCHLER, PAUL, WILSON, YVONNE, WOOD, DAVID, L.
Applicants: SUN MICROSYSTEMS INC, SUN MICROSYSTEMS, INC.
Application year: 2000
Main classification: G06F1
IPC codes: G06F1, G06F21, H04L29