Abstract:
In a method and arrangement for authenticated transmission of a personalized data set or program to a hardware security module in a device such as a franking machine, a system manufacturer buys security modules, from a security module manufacturer and incorporate the security modules at a production site in the device and loads a data set and/or an application program into the security module, making the device operable. Authentication occurs using a first security module-specific fixed code, a second security module-specific fixed code that is calculated from the first code according to a given algorithm, and a third security module-specific fixed code that is calculated from the second code and the data in the data set and/or in the program.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method for the authenticated transmission of a data set and/or of a program from a host to a hardware security module i  (HSM i ), a system for implementing such a method, and a delivery package for carrying-out such a method. 
     2. Description of the Prior Art 
     In the sales and application channels of hardware security modules (HSM) there is typically made a differentiation between the HSM manufacturer, the system manufacturer, who integrates the HSMs in his system products, and the end user of these system products. A typical example of such a system product is a franking machine. 
     In doing so, the sales channel has to be protected such that system products with false HSMs or with HSMs, which comprise non-authorized software, cannot be made available to end users, for example by unauthorized third parties. 
     For this purpose, it is known for an HSM manufacturer to individualize an HSM after the manufacture thereof, for example by irreversibly implanting a unique or one-to-one serial number or the like, i.e. store in an HSM memory. Irreversible means herein that later neither a deletion nor a modification is possible. In most cases, further a cryptographic key is established in every HSM. After the electronic circuitries of the HSM have undergone and passed all hardware and software tests, the HSM with the electronic circuitries is sealed by producing or, if already present, activating its manipulation protection. Besides potting, various measures for this purpose are known in the art, and exemplarily only reference is made to documents DE 198 16 572 A1, DE 198 16 571 A1, EP 1 035 516 A2, EP 1 035 517 A2, EP 1 035, 518 A2, EP 1 035 513 A2 and DE 200 20 635 U1. 
     Then in a pre-personalization phase a code-verifying key is imported into the HSM, by means of which the HSM can later verify, whether or not a loaded application program is authorized. Provided with this code-verifying key an HSM is supplied to the system product manufacturer. On a separate way the system product manufacturer obtains a code-signing key, by means of which he is able to sign application programs. Code-verifying key and code-signing key are a key pair with a one-to-one relationship and are typically produced in an external host system of the HSM manufacturer, which then transmits the code-verifying key via an authenticated communication channel into the HSM. The authentication of the communication channels is normally made by rigorous access controls to the production and pre-personalization process, and supervision of incoming and outgoing material flows and employees by means of the four eyes principle, etc. 
     In the personalization phase, an application program can be loaded into the HSM, which is then later used in an operative phase (at the end user). In order to prevent that during the personalization phase non-authorized application programs are loaded into the HSM, the HSM requires a digital signature for every application program. This digital signature is verified after loading the application program with the code-verifying key, and with a positive verification the application program is accepted and persistently stored. In case of a negative verification a deletion of the newly loaded application program is carried out. 
     The personalization phase can be split up, so that the personalization process is started with the manufacture of the system products (pre-initialization) and terminated in the respective sales center of a target market (initialization). During the pre-initialization an import of an authenticated boot loader, registration of the HSM in a PKI of the system product manufacturer and loading of the application program for the end user take place. The initialization is then made by establishing and exchanging cryptographic keys for the end user. With regard to the technology of authenticated of boot loaders, reference is for example made to the document DE 101 37 505 B4. 
     Since the code-verifying key is the “public” portion of an asymmetric key pair (private/public key), it can be imported into all HSMs of a production, without a risk for the security of the respective (secret or to be kept secret) code-signing key. 
     HSMs are also known that operate with a secure communication interface to the host system on the base of symmetric encryption systems. The host system is enabled to initialize a so-called session with the HSM and to then transmit data sets and/or programs into the HSM, and that encrypted by means of a session key. For this purpose, a system manufacturer obtains the cryptographic session keys on a separate way from the HSM manufacturer. The session key must however be kept at the production site, and that in a secure environment, for example in an HSM integrated in the host and having a secure host processor and a secure host memory. This is of course required separately for every production site, which is expensive in setting-up and maintaining. 
     Therefore all above variants have the common drawback that at a production site of a system manufacturer high security measures are necessary, in order to prevent fraudulent use of codes and/or data sets and/or application programs. The device and the maintenance of such high security measures is expensive, time-consuming and prone to malfunctions. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to provide a method and a system for the authenticated transmission of a data set and/or of a program from a host to an HSM at a production site, which can be implemented in an unprotected or only poorly protected environment and which secures nevertheless a high security against loading of unauthorized data sets and/or programs into the HSM to be produced or completed. 
     A data set encompasses a sequence of characters coding information. The sequence of characters may consist of numbers or be alphanumeric. 
     A program is composed of program lines comprising program instructions. The program instructions effect in a processor, on which the program runs, the execution of mathematical operations and if applicable the output of data sets as results of the mathematical operations. 
     In most cases programs also include data sets, which are required for the execution of the mathematical operations and which are invariant. Variant data sets, which are required for the mathematical operations, are typically entered via an interface. 
     A host is a central computer, to which different HSMs can be connected simultaneously or successively, and from which data sets and/or programs are transmitted via an interface to every HSM according to the host program. 
     An HSM is a hardware security module, which typically includes an electronic circuitry, at least one interface and mechanical, electrical and/or electronic protections against an unauthorized access. The electronic circuitry usually includes an HSM processor, an HSM memory and control outputs, which are driven according to an application program processed in the control processor. The HSM memory often is composed of different memory units or memory sections, wherein programs, data sets, intermediate program results etc. are stored. 
     A variable code is a sequence of characters, which varies with every generation of the variable code, i.e. successive variable codes have different sequences of characters. Typical examples for variable codes are time codes, in the simplest case a sequence of characters increased by a given n-fold (n=positive natural number) of a processor cycle each by a character unit, random sequences of characters (can for example be generated in the HSM processor with a program for calculating random numbers), or linear or non-linear sequences of characters calculated according to given algorithms. A variable code may be composed partially of a fixed code, i.e. a portion of the sequence of characters does not vary, whereas another portion of the sequence of characters is modified with every generation. 
     A fixed code is a sequence of characters, which is invariant, i.e. remains identical with every readout from a memory. 
     An individual code is a code, which is assigned in a one-to-one relationship to a device, for example to an HSM, to a program or to a data set. Different devices, programs or data sets, even with identical contents or structure, have different assigned individual codes. An individual code is so to speak a unique name for a device, program, or data set. Essential is the respective assignment. Examples for individual fixed codes include serial numbers, sequence numbers, etc. 
     An algorithm is a program code, which codes a defined calculation rule. 
     An HSM manufacturer manufactures the HSM as an independent structural unit and sells such HSMs to system manufacturers. 
     A system manufacturer buys HSMs from an HSM manufacturer, incorporates them at a production site in a system device and loads a data set and/or an application program (if applicable also several data sets and/or application programs) into the HSM, whereby the system device becomes operable, for example as a franking machine. The system manufacturer&#39;s site and the production site are normally not the same, they may even be in different countries. Normally, to a system manufacturer&#39;s site are even assigned several different production sites. At the system manufacturer&#39;s site are made (in addition to logistic planning and shipment of the HSMs to the different production sites) the generation, administration and shipment of keys or codes and/or of data sets or application programs to one or several production sites. 
     An interface permits the exchange of data and/or programs between two processors or processor systems. Every device with a processor system, into which data and/or programs can be loaded, has an interface. An interface connects a device internal BUS with a device external transmission medium. As transmission media can be used cables, wire or glass fiber-bound, and wireless transmissions, such as by means of radio waves or IR. 
     Transformation of a code en compasses a conversion of the sequence of characters of the code into a different sequence of characters according to a given algorithm. A reverse transformation converts the sequence of characters of the transformed code back into the sequence of characters of the original code, this is thus a symmetric algorithm reverse or inverse to the algorithm used for the transformation. 
     A hardware configuration parameter HWP i  is a code, which is individual for an HSM i , and which serves for identifying the HSM type, to which the HSM i  belongs, for example by stating the memory size, security degree, etc. 
     An authentication key Authkey i  is a code, which is individual for the HSM i , and which serves for the encryption of a variable code or for the decryption of an encrypted variable code. 
     A transport key TK i  is a code, which is individual for an HSM i , and which serves for making available a secret code for a communication of an HSM i  during a personalization, and that for obtaining a session key. 
     A MAC i  is a message authentication code being individual for an HSM i , which for example is formed by the data of the data set and/or of the application program. 
     An additional fixed code portion is a fixed code, which may be individual or not for an HSM i , and is different from the above fixed codes. 
     A boot loader program is a boot program, such as described for example in the document DE 101 37 505 B4. 
     An application program is a program, which controls and/or protocols in a device, in which the HSM is integrated, processes with usual software techniques, such as for example a franking process, if applicable according to acceptable user entries. 
     A key code is an arbitrary code, which serves for the encryption and/or decryption. This may for example be a public key, e.g. with a PKI certificate of the host system. 
     The term franking machine generally is a device, by which franking of mailpieces, such as letters, small parcels, big parcels, and other containers for delivery, can be done. These are thus also mail processing machines and computers with mail processing functions, for example franking by PC. 
     A delivery package is a device with assigned data sets, codes, or programs. Data sets, codes and/or programs may be stored on one or on different data carriers, such as optical or magnetic data carriers, chip cards or the like. The term storage on a data carrier also comprises the recording on a paper substrate or the like. The device and the data carrier or data carriers may be combined to a package unit or be provided and delivered in separate package units. In lieu of a delivery of a data carrier, a transmission by remote data transmission, for example through the internet, is also possible, then an information unit replaces the data carrier. 
     The aforementioned object, is achieved in accordance with the invention by a method for the authenticated transmission of a data set and/or of a program from a host to a hardware security module i  (HSMi) comprising the following steps: 
     a) at a system manufacturer&#39;s site, for i HSM i , each having an HSM processor, a code generator that generates a variable code Cw and an HSM memory connected with the HSM processor, a first HSM individual fixed code Fc 1   i  a second HSM individual fixed code Fc 2   i , and a third HSM individual fixed code Fc 3   i  are determined, 
     the second fixed code Fc 2   i  is calculated from the first fixed code Fc 1   i  according to a given algorithm, 
     the third fixed code Fc 3   i  is calculated from the second fixed code Fc 2   i  and data of the data set and/or of the program, and 
     all the fixed codes Fc 1   i , Fc 2   i  and Fc 3   i  optionally are different from each other, 
     b) at the system manufacturer&#39;s site, the first fixed code Fc 1   i  and the second fixed code Fc 2   i  or the given algorithm are stored in the HSM memory, 
     c) at least one of the HSM is transported to a production site, and the first fixed code Fc 1   i , optionally the data set and/or the program, and the third fixed code Fc 3   i  are transmitted to the production site and stored in the host with host processor and host memory, 
     d) at the production site, the HSM processor and the host processor are connected with each other by at least one interface, 
     e) the host processor transmits to the HSM i  an initialization data sequence, by means of which a response data sequence, optionally including an identification of the HSM i , is requested, 
     f) after reception of the response data sequence and optionally successful identification of the HSM i , the host processor couples the data set and/or the program to be transmitted with the third fixed code Fc 3   i  assigned to the HSM i  and stored to a transmission data set and transmits the transmission data set to the HSM processor, 
     g1) the HSM processor calculates, using the stored given algorithm, the second fixed code Fc 2   i  or reads it out from the HSM memory ( 5 ) and compares it with a second fixed code Fc 2   i ′ calculated from the transmission data set, or 
     g2) the HSM processor calculates, using the stored given algorithm, the second fixed code Fc 2   i  and therefrom in connection with the transmission data set or the transmitted data set and/or program the third fixed code Fc 3   i  and compares it with the third fixed code Fc 3   i ′ comprised in the transmission data set, and 
     h) in case of agreement of the second fixed code Fc 2   i  with the second fixed code Fc 2   i ′ or of the third fixed code Fc 3   i  with the third fixed code Fc 3   i ′, the authorization and approval of the data set and/or of the program for the activation in the HSM i  are effected. 
     Optionally, the following steps may immediately follow step e): 
     e1) the HSM i  generates with the means for the generation ( 4 ) of a variable code a variable code Cw, stores this variable code Cw in the HSM processor and transmits this variable code Cw via the interface to the host processor, 
     e2) the host processor transforms the received variable code Cw by means of the first fixed code Fc 1   i  stored and assigned to the HSM i  into a transformed variable code Cwt and transmits the transformed variable code Cwt to the HSM processor, and 
     e3) the HSM processor carries out with the received transformed variable code Cwt with the first fixed code Fc 1   i  a symmetric transformation being reverse to the transformation of the step e2) and compares the obtained back-transformed variable code Cw rt  with the variable code Cw stored in step e1) and transmits in case of agreement a confirmation data sequence to the host processor. 
     It is achieved by the invention that at a production site there are not required any special security measures for the provision of the first fixed code Fc 1   i  and of the third fixed code Fc 3   i  and the transmission thereof to the HSM i . On the other hand, nevertheless, there is a high security against the loading of unauthorized data sets and/or program, since without knowledge of the algorithms for the calculation of the second fixed code Fc 2   i  from the first fixed code Fc 1   i , and for the calculation of the third fixed code Fc 3   i  from the second fixed code Fc 2   i  it is not possible to generate a third fixed code Fc 3   i  and combine it with an (unauthorized) data set or program, which would be detected by the HSM i  as valid. These algorithms are not freely accessible at the production site, but are only stored in the HSM i . As a result, the first fixed code Fc 1   i  and the third fixed code Fc 3   i  can be provided without security measures at the production site, and nevertheless unauthorized data sets or programs cannot successfully be loaded into an HSM. A considerable simplification at the production site is achieved, and the necessary security against loading unauthorized data sets and programs is maintained. 
     In case of a negative comparison in one of the steps e3) or g1) or g2), resp., an abortion of the process is effected. In case of a negative comparison in step e3), there is therefore no transmission of the transmission data set. In case of a negative comparison in step g1) or g2), resp., a deletion of the transmitted data set or program from the HSM memory is effected. 
     Basically, the steps e1) to e3) represent a sequence “Hello Request, Hello Reply (with encrypted variable code Cw), Challenge Request, Challenge Reply” as known from the network technology. An authorization of the host with regard to the HSM i  takes place. For the purpose of the invention it is possible that the host also transmits a (if applicable different) to the HSM i , whereupon the HSM i  encrypts the received variable code by means of the first fixed code Fc 1   i  and transmits it back to the host, which then performs a back-transformation by means of the fixed code Fc 1   i  and compares the result with the stored variable code. This additional authorization may for example be made between the steps e3) and f). 
     The data set transmitted to the HSM i  may for example be a key code. The program transmitted to the HSM i  may be a boot loader program or an application program. 
     The fixed codes used according to the invention may in principle be of any kind. In the practice it is preferred that the first fixed code Fc 1   i  is an authentication key Authkey i , and that i is a serial number of the HSM i  or an individual data set correlated therewith. The second fixed code Fc 2   i  can be calculated from a serial number i  or i itself, a hardware configuration parameter HWP i , Authkey i , a transport key TK i  and optionally an additional fixed code portion with a defined algorithm and thus form a session key i : 
     Session key i , =f (serial number i , HWP i , Authkey i , TK i , fixed code portion i ), wherein i is a positive natural number. The system manufacturer obtains the respective keys from the HSM manufacturer, and there the calculations are carried out, as described above. 
     Before the method according to the invention is carried out, the production of the HSM i  and its delivery to the system manufacturer together with the generated and assigned codes takes place. For this purpose, before the step a) at least one HSM i  is produced by the HSM manufacturer, and by the HSM manufacturer at least i and the first fixed code Fc 1   i  is assigned to the HSM i . The HSM i  together with the information on i and Fc 1   i  is then delivered to the system manufacturer. At the HSM manufacturer, the assignment of the third fixed codes Fc 3   i  and its delivery can also be made, this is however not necessarily required. In any case, however, at the HSM manufacturer, the algorithms and codes necessary for the method according to the invention are loaded into the HSM i . In detail the HSM manufacturer may also store HWP i  in the HSM i  and transmit Authkey i  and TK i  to the system manufacturer. 
     The host may in principle be arranged in an arbitrary manner, since a secure transmission cable to the HSM is not required. Thus, the host may be provided at the HSM manufacturer or at the system manufacturer. Normally, however, it is preferred that the host is provided at the production site. 
     Typically the data set and/or the program are transmitted from an application server to the host before the step i). 
     In view of the advantages according to the invention, as described above, the host can also be operated as a stand-alone host and needs not have any security functionality. For example, secured transmission cables and/or host-own HSMs are therefore not required. 
     The invention also relates to a system that implements the method described above. The above explanations with regard to the method, including the preferred embodiments apply in an analogous manner to the system according to the invention. The invention also relates to a processing assembly that implements the method described above. 
     For the invention it is preferred that the HSM i  is intended for the integration in a franking machine or forms a portion of a franking machine. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically illustrates the basic components of a system according to the invention for secure transmission of a dataset and/or of a program. 
         FIGS. 2   a  and  2   b , in combination, are a flowchart for an embodiment of a method according to the invention for secure transmission of a dataset and/or of a program. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Example 1 
     Production of an HSM and Delivery to a System Manufacturer 
     An HSM manufacturer produces the hardware for the HSM her and stores the software therein. To every HSM i  is assigned a serial number i , an HWP i , an Authkey i  and a TK i . The serial number i  and the HWP i  are stored in the respective HSM i . 
     The HSM i  thus produced is supplied to the system manufacturer and the Authkey i  and TK i  assigned to the HSM i  are transmitted to the system manufacturer together with the assignment. 
     Example 2 
     Production Preparations of the System Manufacturer and Deliveries to a Production Site 
     At the system manufacturer, for every HSM i  a session key i  is calculated according to the formula 
     Session key i =f (serial number i , HWP i , Authkey i , TK i , fixed code portion i ), 
     and stored either in the HSM memory, or the given algorithm for this is stored in the HSM i . 
     By means of the session key i  and using data from a data set or program to be installed at the production site then an MAC i  respectively is calculated. 
     Finally the HSM i , Authkey i , and if applicable the data set or the program, if not yet existing at the production site, are transmitted to the production site, and that under respective assignment for example based on i or a serial number i . 
     Example 3 
     Representation of the Components of a System According to the Invention 
     In  FIG. 1  can be seen the components of a system according to the invention for the secure transmission of a data set and/or of a program in a production lot of HSM i    2   1 ,  2   i ,  2   n . Each HSM i    2   1 ,  2   i ,  2   n  is provided with an HSM processor  3 , an HSM memory  5  and means for the generation  4  of a variable code Cw. In each HSM memory  5 , a first HSM-individual fixed code Fc 1   i  and the second fixed code Fc 1   i  are stored. 
     Furthermore, there is a host  1  with a host processor  6 , a host memory  7  and usual interfaces  8   1 ,  8   i ,  8   n ,  8   H  for the connection of the HSM processors  3  to the host processor  6  by a BUS  10 . In the host memory  7 , the data set and/or the program (application), the first fixed code Fc 1   i  and a third fixed code Fc 3   i  are stored. These data were previously transported by means of a data carrier  9  to the host and stored therein. 
     The host processor  6  is provided for the delivery of an initialization data sequence to the HSM processor  3 . The HSM processor  3  is provided for storing and delivering the generated variable code Cw to the host processor  6 . The host processor  6  is further provided for the transformation of the received variable code Cw with the first fixed code Fc 1   i  into a transformed variable code Cwt and for the return of the transformed variable code Cwt to the HSM processor  3 . The HSM processor  3  is further provided for the back-transformation of the received transformed variable code Cwt with the first fixed code Fc 1   i  into a transformed-back variable code Cw rt  and its comparison with the stored variable code Cw and in case of agreement for the delivery of a confirmation data sequence to the host processor  6 . The host processor  6  is further provided after reception of the confirmation data sequence for the coupling of the data set and/or of the program to be transmitted with the third fixed code Fc 3   i  assigned to the HSM i    2   1 ,  2   i ,  2   n  and stored to a transmission data set and for the delivery of the transmission data set to the HSM processor  3 . The HSM processor  3  is further provided for the determination of the second fixed code Fc 2   i  by means of the stored given algorithm or for the readout from the HSM memory  5  and the comparison thereof with a second fixed code Fc 2   i  calculated from the transmission data set. The HSM processor  3  is finally provided in case of agreement of the second fixed code Fc 2   i  with the second fixed code Fc 2   i ′ for the authorization and approval of the data set and/or of the program for the activation in the HSM i    2   1 ,  2   i ,  2   n . 
     In the embodiment, the program is an application program. The first fixed code Fc 1   i  is an authentication key Authkey i . i is a serial number of the HSM i    2   1 ,  2   i ,  2   n  or an individual data set correlated therewith. The second fixed code Fc 2   i  can be calculated from i, a hardware configuration parameter HWP i , Authkey i , a transport key TK i  and optionally an additional fixed code portion with a defined algorithm. 
     The host  1  is a stand-alone host, arranged at the production site and has no security functionality. 
     Example 4 
     Final Production or Personalization at the Production Site 
     The system according to  FIG. 1  is arranged at the production site, and the session protocol shown in  FIG. 2  is carried out therewith. For this purpose, host  1  and HSM i    2   1 ,  2   i ,  2   n  are first connected by the BUS  10 . 
     In  FIG. 2 , on the left side, steps of the process or of the method are shown, which are carried out by an HSM  2   1 ,  2   i ,  2   n , and on the right side, steps of the process or of the method are shown, which are carried out by the host  1 . Arrows between the left side and the right side indicate a data transmission via the BUS  10 . 
     In a first step  201 , the host  1  generates and transmits a Hello Request. The HSM  2   1 ,  2   i ,  2   n  receives this Hello Request in step  101 . This triggers in the HSM  2   1 ,  2   i ,  2   n  the generation of a random number (Rand) and the storage thereof in step  102 . Then in step  103  the random number (Rand) is sent as a Hello Reply to the host  1 . The host  1  receives the Hello Reply in step  202 . This sets off step  203 , in which the host  1  reads the Authkey (Fc 1   i ) from the host memory  7 . Then the host processor  6  executes in step  204  an encryption of the random number (Rand) by means of the Authkey and transmits in step  205  the encrypted random number (Rand) to the HSM  2   1 ,  2   i ,  2   n  as a Challenge Request. The HSM  2   1 ,  2   i ,  2   n  receives the Challenge Request in step  104 . In step  105  the Authkey (Fc 1   i ) is read from the HSM memory  5  and in step  106  a decryption of the Challenge Request is performed. In step  108  a comparison of the decrypted Challenge Request with the random number stored in the HSM  2   1 ,  2   i ,  2   n  takes place. In case of non-agreement step  107  follows, in which an abortion of the protocol and an error message are effected. In case of agreement, step  109  follows, in which a Challenge Reply is delivered from the HSM  2   1 ,  2   i ,  2   n  to the host  1 . The host receives in step  206  the Challenge Reply and proceeds to step  207 , in which an MAC (Fc 3   i ) and the application are read from the host memory  7  and combined to a transmission data set and delivered to the HSM  2   1 ,  2   i ,  2   n . The HSM  2   1 ,  2   i ,  2   n  receives the transmission data set in step  110 , reads in step  111  the session key (Fc 2   i ) from the HSM memory  5  and verifies in step  113 , whether MAC and session key are in agreement or are correlated with each other in a given manner. If not, step  112  follows, in which an abortion of the protocol, an error message and a deletion of the application from the memory  5  of the HSM  2   1 ,  2   i ,  2   n  take place. If yes, steps  114  and  115  or  208  and  209  follow, which represent a final routine for the communication between host  1  and HSM  2   1 ,  2   i ,  2   n . In step  116  finally is effected an approval or activation of the application in the HSM  2   1 ,  2   i ,  2   n , since it is authorized, and an end user can use the device, in which the HSM  2   1 ,  2   i ,  2   n  is integrated, in a usual way. Steps  117  and  210  are termination steps. 
     Although modifications and changes may be suggested by those skilled in the art, it is the intention of the inventor to embody within the patent warranted hereon all changes and modifications as reasonably and properly come within the scope of his contribution to the art.