Abstract:
Embodiments of the invention provide a high degree of security to a computer or several computers connected to the Internet or a LAN. Where there is a high degree of confidentiality required, a combination of hardware and software secures data and provides some isolation from the outside network. An exemplary hardware system consists of a processor module, a redundant non-volatile memory system, such as dual disk drives, and multiple communications interfaces. This security system must be unlocked by a passphrase to access data, and all data is transparently encrypted, stored, archived and available for encrypted backup. A system for maintaining secure communications, file transfer and document signing with PKI, and a system for intrusion monitoring and system integrity checks are provided, logged and selectively alarmed in a tamper-proof, time-certain manner. The encryption keys can be automatically sent encrypted to be escrowed with a secure party to allow recovery.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims benefit of United States provisional patent application Ser. No. 60/252,720, filed Nov. 22, 2000, which is herein incorporated by reference. 
     
    
     
       TECHNICAL FIELD OF THE INVENTION  
         [0002]    This invention generally relates to data processing. More particularly, embodiments of the invention relate security provisions for on-line communications as well as secure data storage.  
         BACKGROUND OF THE INVENTION  
         [0003]    When the computer replaced the file cabinet as the storage place for documents there remained the threat to these documents of physical loss through theft or destruction as by fire or flood. In addition the computer added its own methods of destruction of data as by file corruption, computer virus or disk crash. Most corporations also maintain system administration that allows system administrators to have access to most computer data. Not only does this imply trust in the department with administrator or root authorization, but also the object of most computer hacking is to obtain this level of authorization, and this is often accomplished. Operating with user or administrator authorization in a user&#39;s computer allows file deletion and modification and could allow disk formatting, emailing of any file to outside parties, and modification of the computer&#39;s security settings. This is difficult to overcome in a computer without restricting the normal secure functioning of the computer, since the attacker can often attain the ability to perform any function a legitimate user of the computer can perform. Common email communications of this sensitive information is in plain text and is subject to being read by unauthorized code on the senders system, during transit and by unauthorized code on the receiver&#39;s system. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0004]    So that the manner in which the above recited features, advantages and objects of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings.  
         [0005]    It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.  
         [0006]    [0006]FIG. 1 shows a high level diagram of an embodiment of a security device, termed a Lockbox, coupled to an end user&#39;s computer (PC) and to a network (e.g., a LAN). Information from the PC is transferred to the security device where the information is encrypted and stored. Illustratively, information is distributed according to client in order to be available for customer viewing over a secure socket. However, the Lockbox also supports standard file structures and can store any normal computer folders.  
         [0007]    [0007]FIG. 2 shows one use of the Lockbox where a routable static IP address is available to allow the Lockbox to act as a web host to provide enhanced data security and secure communications for a small office environment.  
         [0008]    [0008]FIG. 3 shows an alternative embodiment of the Lockbox as a security and storage system in which files enciphered by an owner&#39;s security device are duplicated on a remotely located third-party ISP host. The host provides access restricted to authorized users.  
         [0009]    [0009]FIG. 4 shows an alternative embodiment of the Lockbox as a security and storage system in which the computer to be secured is located within a corporate LAN. While providing the data security inherent in the Lockbox, the communications security is provided by an encrypted standardized Internet service to either another Lockbox or to a secure third party server with customized software.  
         [0010]    [0010]FIG. 5 shows a client file as viewed by the client under a secure socket connection. This illustrates the client&#39;s ability to view all documents in the folder, to digitally sign selected documents and to securely return documents with comments. This illustratively shows a client file established by “Tom Owner” for viewing by “James Client”.  
       SUMMARY OF THE INVENTION  
       [0011]    To address these problems this invention proposes to offer the computer owner a system establishing a comprehensive security system. Where there is a high degree of confidentially required, a combination of hardware and software secures that data. Running software with a restricted operating system on a separate processor allows security of stored files that cannot be corrupted by commands from a compromised host system. An exemplary hardware system, referred to in this application as a “Lockbox”, consists of a processor module, a redundant non-volatile memory system such as dual hard disks, power conditioning and multiple communications interfaces. The Lockbox is connected by a Local Area Network link to a protected computer or computers. On power-up the Lockbox data is inaccessible until the Lockbox is connected to the appropriate networks and unlocked by a passphrase from a protected computer. After unlocking, the Lockbox can provide files to only a protected computer. The Lockbox regularly archives its files. Data stored in the Lockbox is encrypted before storage and decrypted before delivery to a protected computer transparently to a user. Files delivered to client folders in the Lockbox will trigger an email to the client notifying them of the availability of a communication. The client can only access his folder by establishing a secure socket connection and thereby viewing, digitally signing or modifying the client file contents. Security is further enhanced by a firewall, various system integrity checks, and intrusion detection, all of which log incidents and, if the incident is sufficiently serious, alarms the user. These logs and alarms cannot by disabled by any commands from the host system. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0012]    An exemplary configuration of a Lockbox is illustrated in FIG. 1. The Lockbox enclosure  102  includes power conditioning and UPS  144  and two Ethernet ports  110  and  112  for connection to a protected subnet  150  and to an outside network  151 , respectively. The outside network  151  can be either an outside intranet  146  or the Internet  150 . When an Intranet  146  is employed this customarily connects through a firewall  148  to the Internet  148 . The protected subnet  150  connects to one or more protected user computers represented by  104 ,  106  and  108  by Ethernet connections with any required switches, etc. not shown. Within the Lockbox  102  an encrypted file system  114  encrypts and decrypts on-the-fly Ethernet communications between the protected computers  104 - 106  and the internally stored encrypted data. The files stored in  114  are regularly archived in  116  to provide file access if malicious code in a protected computer erases or alters a file in  114 . The file system  114  also organizes client folders exemplified by  118 ,  120  and  122  in additional to regular files. As shown in the progression from  120  to  122 , there can be an indefinite number of client folders, and a client folder can represent a group of clients. Associated with a client folder are files to be sent to the client, files received from the client, and client information such as client password, email address and digital signature public and private key. A computer task  126  scans for changes in the client folders and sends emails to the client or to the user on receipt of a file to be sent to the client or received from the client, respectively. Another task  124  can be activated to purge a sent message from the system once the client has retrieved it. All incoming and outgoing communications to the outside network  151  passes through an internal firewall  128  to provide a layered security to the protected subnet  150  and to the Lockbox. Traffic is monitored by the firewall  128  and reported to a logging task  130  which also has input from internal integrity checks  132 , which monitors the physical condition of the Lockbox, the functioning of its components, invalid access attempts, and the file access monitor  134 . The file access monitor  134  detects attempts to access selected files as an additional intrusion monitor. The time is continually monitored over the Internet by a task  136  that insures the accuracy of the time stamps in the logs. Any failure of this task is alerted. Any changes in passphrases can be optionally detected by a task  138  to trigger encrypted exchange with a trusted party to escrow the change. In association with the client folders a task  140  can optionally provide a Public Key Infrastructure for the internally stored digital signatures. A task is provided for organizing a network tunneling system  142  to allow secure encrypted communications with ordinary Internet communications protocol to associated software on an outside computer on the Intranet  146  or the Internet  150 . This monitors the encrypted file system  114  to detect changes and, if the change is in a selected file, to coordinate a change in the outside computer to mirror those changes. Conversely, changes in the mirrored files in the outside computer are reflected to  114 .  
         [0013]    [0013]FIG. 2 illustrates the Lockbox connected to an Internet connection  216 , which would normally be a routable, static IP address, through the Lockbox outside port  204 . The Lockbox  200  incorporates the features of  102  in FIG. 1. The Lockbox communicates over the Internet  206  to client boxes on the Internet as illustrated by  220  and  222 . The Lockbox can also communicate to a mirrored outside computer  224  with tunneling mirror software to provide data backup. The Lockbox connects via its Ethernet connection  202  to a protected subnet  214  and from there to one or more protected computers as illustrated by  208 ,  210  and  212 .  
         [0014]    [0014]FIG. 3 illustrates the possibly of securely exporting the function of providing the secure email notification to an outside Internet Service Provider (ISP) using the tunneling mirror service. This is useful if a static, routable IP address is not available to the Lockbox at its connection  316 . Elements  300  to  324  correspond to elements  200  through  224  in FIG. 2, respectively. The ISP  326  is also connected to the Internet  328 . The ISP  326  contains a web server  330  that connects to a mirrored remote client box  332  with software corresponding to the tunneling mirror software  142  in FIG. 1. This software negotiates an encrypted communication with  142  to mirror the client folders in the Lockbox ( 118  through  122  in FIG. 1) to mirrored folders in the ISP illustrated by  334 ,  336  and  338 . Changes in the folders detected by task  342  trigger emails to the client to allow retrieval through a secure socket communication to the ISP. The client, when accessing his folder through the secure socket, can add files to his folder or digitally sign the files in his folder and the mirroring task  332  will communicate this information to the equivalent folders in the Lockbox  300  to allow update of those files by task  142  in FIG. 1. Task  340  allows purging of the client&#39;s selected files on retrieval by the client.  
         [0015]    [0015]FIG. 4 illustrates the use of a Lockbox  400  within a local area network such as a company&#39;s Intranet  418 . Such an Intranet is usually accompanied by a firewall or firewalls  420  to limit access to the Internet  422 . In such a configuration the Lockbox  400  serves to provide a layered protection to the protected subnet  414  and the protected computers connected on that subnet such as  408 ,  410  and  412 . Connection is made to the protected subnet  414  through the Ethernet connection  402 . The Ethernet connection to the outside world  404  serves both as a connection to the Intranet and as a method of providing the tunneling of encrypted Internet standard protocol messages containing information on the files to be mirrored. These tunneled messages  418  can pass through the corporate intranet  418  and firewall  420  to another server  430  located externally on the Internet or locally on the Internet. The server  430  contains an Ethernet port  428  that serves both as an ordinary Internet connection  426  and as a recipient for the tunneled Internet messages  418 . Another Lockbox could function as the server  430 . In the server, task  234  is a web server with the file decryption, functioning as  114  in FIG. 1. The tunneling mirror task  436  mirrors selected files in the Lockbox in communication with task  142  in FIG. 1. To insure accurate file coordination there is an accurate, web-based time synchronizing task  440  in the server corresponding to task  136  in FIG. 1. Optionally the server could have a file server  442  to connect to a local area network at the server&#39;s location via an Ethernet port  432 . This would be useful if the Lockbox  400  is serving consultants on computers  408  through  412  who want to make their local files available to operators at their office on computers such as  446  over their home office local area network  444 . In such a configuration the Lockbox would serve to protect the confidentiality of the consultant&#39;s files from the corporate network  418 , protect the consultant&#39;s computers  408  thru  412  from attacks from the Intranet  418 , and provide physical security to those files through the encrypted file system. Clients and co-workers such as  448  can log on the Internet through an ordinary Internet access  450  to view selected files in client folders over a secure socket connection.  
         [0016]    In a particular embodiment, a file in the Lockbox is shared with a protected computer using standard file sharing. The Lockbox data will therefore appear as another folder or disk drive to an unmodified protected computer. The Lockbox maintains its own encryption of stored data with an internal symmetric encryption key. This insures that the encryption cannot be compromised by data stored on the protected computer. This data in the Lockbox will be unintelligible to anyone having physical possession of the Lockbox or having direct access to the files on the Lockbox. The data stored on the Lockbox is regularly archived to a second disk, with software to coordinate the data archiving and check the integrity of each storage device. In the case of a storage failure, as in a disk crash, the files are maintained in the uncorrupted storage and the user is notified that the corrupted drive must be replaced. On replacement, the data is restored to both drives and operation continues uninterrupted. The archiving of data rather than a straight backup allows data recovery in case an attacker on a protected computer directs the deletion of files. An attacker would not be able to reformat the Lockbox drives since this level of control is not available to a protected computer.  
         [0017]    To ensure that the data is available in the case of a complete physical destruction of the host computer and Lockbox, as in the case of the destruction of the building by fire, the software includes the ability to externally archive the data on a periodic basis. The archive files contain a software wrapper containing non-sensitive information such as the date on which the data is to be allowed to expire. In one embodiment, the file name and all data in the file will be encrypted under a second encryption key, and in another embodiment the name will be unencrypted to allow file searching of the encrypted data.  
         [0018]    Files are archived, either incrementally or by a total memory dump, into local or remote storage. Locally, the archival will be to a removable media, located within the Lockbox or on a protected computer, such as a tape or CDROM, for off-site storage. Since the files on the storage media will be encrypted, the physical loss of the archival media will not pose any security risk since they will be unreadable without the encoding key.  
         [0019]    In one embodiment, off-site storage is provided whereby the Lockbox is periodically and automatically backed up over a secure Internet communications channel. The Lockbox incorporates tunneling software that allows selected files to be mirrored at the off-site storage. This is accomplished by negotiating a secure channel and encrypting the information inside Internet packets which appear to intervening firewalls as normal Internet communications. These packets are unintelligible to any observer. Synchronization software is included to update any files modified between mirroring exchanges.  
         [0020]    In any case, the archival computer would then reconstruct an image of the Lockbox&#39;s encrypted data files and keep that image available for archival retrieval. As these files are stored encrypted, they would be unintelligible to the storing agent. Once restored to the Lockbox, the user would again have unencrypted access to the files by the operation of the Lockbox&#39;s decryption ability. The files would be referenced in the archival files by their encrypted identifiers and the Lockbox owner can selectively restore them by reloading into the Lockbox for decryption.  
         [0021]    Provision is made in the code to optionally automatically escrow to a trusted third party or internal agent the encryption key and the passphrase that unlocks the Lockbox. This will insure that the data remains unintelligible to any third-party archivist but is still available to the authorized person in the case of unforeseen circumstances such as the physical destruction of the Lockbox or the removal of the user. The separation of the encrypted data access from the key storage access is designed to prevent one party, such as the system administrator, from having access to both, and therefore access to the data. The escrow agent will maintain a public key under which the Lockbox automatically encrypts the selected access keys and emails them back to the agent. This is automatically done each time the keys are changed. In the exceptional case where the keys are lost the escrow agent will return the keys after proper authentication. The key may be stored in a symmetric encrypted form on the Lockbox pending receipt of acknowledgment from the escrow agent in order to prevent intermediate loss.  
         [0022]    When the protected computers are located within a host local area network, a client cannot normally establish secure socket communications since such computers do not normally have a routable static IP address. In this case the mirrored remote client functionality can be provided by an associated Lockbox at a static IP address on the corporate Internet interface, or a secure server at a third party running parts of the Lockbox software, as shown in FIG. 4. The Lockbox contains code for negotiating an encryption with a correspondent computer and encrypting file transfers with that correspondent computer by embedding the encrypted data within ordinary Internet packets. This is referred to as tunneling through the Internet. The secure tunneling functionality of the Lockbox will insure the security of communications while traveling between the Lockbox and the corresponding secure server or Lockbox.  
         [0023]    Where the Lockbox is connected to the Internet, as a customer service there can be regular scans of the interface to test for vulnerabilities. This, together with the internal system health monitor, detection of invalid logon attempts, firewall intrusion detection, and the disk integrity tests, will provide warnings of impending or actual problems. Such warnings are logged and, if of sufficient importance, alarmed to the protected computers. These logs and alarms cannot be turned off or erased by the protected computers, so an intruder has no way of masking his attacks. The logs can be cleared on an alarmed command, deleting only those logs before a predetermined time before the command. This prevents an intruder from deleting those logs that evidenced his intrusion.  
         [0024]    Where there are several protected computers with a need to access files while maintaining separate confidentiality, and confidentiality from each other, the system could use traditional restricted shared file access to provide separate user areas.  
         [0025]    The Lockbox includes a web server with a passphrase-protected, secure socket viewing of client folders. The user sets up the client folders to be accessible for a particular set of users names and associated passphrases and digital signatures. This would allow the client secure access to documents selected by the secure computer owner as accessible for that user and password, and the ability to securely return documents. FIG. 5 shows one example of such a client view of the documents and shows one example of client options. The establishment of the documents, the notice to the client of the availability of the documents, and the access by the client to the documents would all be logged and be archived to address any subsequent issues of failure to communicate. Notice would be sent to the Lockbox owner of documents available to the client for whom no access attempts were made within some established period. The communications with the client may also include provision for digital signatures of client documents, using, for example, the Digital Signature Standard (DSS) to allow client authorization of documents. Optionally notice would be sent to the Lockbox owner if selected documents were not signed within an established period. Forms are included that negotiate with the client a passphrase for message retrieval and to establish a passphrase for a client&#39;s digital signature. The passphrase for message retrieval can be shared with the secure computer user, but the passphrase for the digital signature is not shared with the Lockbox owner. The private key for the digital signature is internally stored and is inaccessible by any party, being only used internally within the Lockbox to generate a document signature. A letter describing the reliance on the digital signature, one example of which is shown in Table 1, is sent to the client for his signature and witnessing, and is to be returned to the secure computer owner as possible evidence of detrimental reliance. This system is the internal Public Key Infrastructure (PKI).  
               TABLE I                           This document acknowledges the establishment of a digital signature with the accompanying       public key. The undersigned acknowledges that this key was generated with the undersigned&#39;s       password. In the future (****Insert Attorney&#39;s name****) will rely on digital signatures       generated by you using this password as evidence of your approval and having under some       statutes the same force and effect as a written signature.*               In accepting the validity of this digital signature, you understand that (****Insert Attorney&#39;s       name****) has no access to your private (signing) key without your giving (*****him or       her*****) your pass phrase. The pass phrase should not be shared with anyone to whom you do       not wish to give signing authority. You have chosen (*****to have/not to have*****) an email       sent to you confirming every signing. The association between the key and the pass phrase is       inaccessible and in case of accidental disclosure of the pass phrase (****Insert Attorney&#39;s       name****) should be immediately notified so the pass phrase can be deactivated and a new       digital signature and pass phrase generated. This signature will be cancelled on your written       request to prevent use after cancellation.                       Acknowledged on (*****insert date****),                               {overscore (OWNER OF DIGITAL SIGNATURE        )}                               {overscore (ATTORNEY SPONSOR OF DIGITAL SIGNATURE )}                               {overscore (WITNESS                    )}                          
 
         [0026]    Because the time stamping of the logs is critical to proper interpretation of the sequence of events surrounding an incident, the Lockbox includes in its software the ability to regularly correct its internal clock to a standard available via the Internet. If desired, the Lockbox can regularly or on demand communicate with a third party source to establish to communicate the results of its diagnostics and possible need for maintenance. To provide evidence of intrusions, the passphrase to unlock the Lockbox and to access files can use a letter of the day or of the month (e.g. third letter of the day or second letter of the month) so that any captured passphrases will eventually become invalid, triggering an access alarm.  
         [0027]    A logging system keeps track of all communications, the firewall transactions, the unlocking attempts, file access to selected files, client folder transactions and timeouts, root access to the Lockbox operating system, and system parameters such as power supply levels, system temperatures, disk errors, etc. The time stamping of this log is kept accurate by the internal clock. No user can delete the logs without a non-avoidable delay and an alarming of the log deletion event. Significant events in the log are also alarmed to the user.  
         [0028]    While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.