Abstract: Computer-implemented methods for privacy attribute based credentials include issuing a privacy-preserving attribute-based credential, which is signed with a private key and has a unique credential handle; updating an accumulator in a tamperproof log to incorporate the credential handle; and facilitating providing access to a service in response to a zero-knowledge proof that the accumulator contains the credential handle. The methods also include generating revocation conditions and initial revocation information; submitting the initial revocation information and the revocation conditions to the tamperproof log; revoking a credential by adding a credential handle of the credential to the initial revocation information; and submitting the updated revocation information to the tamperproof log. Further, the methods include writing to the tamperproof log an audit token that contains an encrypted credential handle, which is encrypted by an auditor's public key that is published on the tamperproof log.

Abstract: A method is provided for communicating messages between sender and receiver computers, connectable via a network to a system of servers, based on authentication of receiver passwords, associated with respective receiver IDs, by the system. A method is also provided for receiving a message from a sender based on authentication of a receiver password, associated with a receiver ID, by a system of servers, in a network, wherein each server stores for the ID a ciphertext produced by encrypting the receiver password under a public key via a homomorphic threshold encryption scheme having a threshold, and a key-share of a secret key corresponding to that public key, and stores an encrypted message from the sender encrypted under the public key. Systems are provided including servers, for communicating messages between sender and receiver computers based on authentication of receiver passwords, associated with respective receiver IDs, by the system.

Abstract: A system has ??2 servers. At least each of a set of authentication servers stores a key-share ski of secret key sk, shared between q of the ? servers, of a key-pair (pk, sk). An access control server sends an authentication value to a subset of the authentication servers. The authentication value was formed using a predetermined function of a first ciphertext for a user ID and a second ciphertext produced by encrypting a password attempt under public key pk using a homomorphic encryption algorithm. The authentication value decrypts to a predetermined value if the password attempt equals the user password for that user ID. Each authentication server in the subset produces a decryption share dependent on the authentication value using the key-share ski. The access control server uses decryption shares to determine if the authentication value decrypts to the predetermined value, if so permitting access to a resource.

Abstract: Computer-implemented methods for privacy attribute based credentials include issuing a privacy-preserving attribute-based credential, which is signed with a private key and has a unique credential handle; updating an accumulator in a tamperproof log to incorporate the credential handle; and facilitating providing access to a service in response to a zero-knowledge proof that the accumulator contains the credential handle. The methods also include generating revocation conditions and initial revocation information; submitting the initial revocation information and the revocation conditions to the tamperproof log; revoking a credential by adding a credential handle of the credential to the initial revocation information; and submitting the updated revocation information to the tamperproof log. Further, the methods include writing to the tamperproof log an audit token that contains an encrypted credential handle, which is encrypted by an auditor's public key that is published on the tamperproof log.

Abstract: A method is provided for communicating messages between sender and receiver computers, connectable via a network to a system of servers, based on authentication of receiver passwords, associated with respective receiver IDs, by the system. A method is also provided for receiving a message from a sender based on authentication of a receiver password, associated with a receiver ID, by a system of servers, in a network, wherein each server stores for the ID a ciphertext produced by encrypting the receiver password under a public key via a homomorphic threshold encryption scheme having a threshold, and a key-share of a secret key corresponding to that public key, and stores an encrypted message from the sender encrypted under the public key. Systems are provided including servers, for communicating messages between sender and receiver computers based on authentication of receiver passwords, associated with respective receiver IDs, by the system.

Abstract: A system has ??2 servers. At least each of a set of authentication servers stores a key-share ski of secret key sk, shared between q of the ? servers, of a key-pair (pk, sk). An access control server sends an authentication value to a subset of the authentication servers. The authentication value was formed using a predetermined function of a first ciphertext for a user ID and a second ciphertext produced by encrypting a password attempt under public key pk using a homomorphic encryption algorithm. The authentication value decrypts to a predetermined value if the password attempt equals the user password for that user ID. Each authentication server in the subset produces a decryption share dependent on the authentication value using the key-share ski. The access control server uses decryption shares to determine if the authentication value decrypts to the predetermined value, if so permitting access to a resource.

Abstract: A method, apparatus, and a computer readable storage medium having computer readable instructions to carry out the steps of the method for anonymous access to a database. Each record of the database has different access control permissions (e.g. attributes, roles, or rights). The method allows users to access the database record while the database does not learn who queries a record. The database does not know which record is being queried: (i) the access control list of that record or (ii) whether a user's attempt to access a record had been successful. The user can only obtain a single record per query and only those records for which he has the correct permissions. The user does not learn any other information about the database structure and the access control lists other than whether he was granted access to the queried record, and if so, the content of the record.

Abstract: A cryptographic method is provided for a host system having an associated trusted platform module. A first contribution to a message is computed by the TPM based on a first secret parameter stored in the TPM. The host system computes a second contribution to the message based on a second secret parameter stored in the host system outside the TPM. The first and second contributions to the message are then combined by either the host or the TPM and a first proof is conducted, proving to the host system that the contribution of the TPM was computed correctly or proving to the TPM that the contribution of the host was computed correctly.

Abstract: A method and system for performing transactions between a client and a server. The client sends to the server a transaction request for performing a transaction, and receives from the server a transaction policy. The client displays a first representation of the transaction policy depicting transaction policy options for fulfilling the transaction policy. After the user selects a first transaction policy option, the client displays a second representation of the transaction policy, depicting at least one mechanism pertaining to the first transaction policy option for satisfying the requirements of the first transaction policy option. After the user selects a first mechanism, the client depicts evidence options for each requirement of the first transaction policy option. After the user selects an evidence option for each requirement of the first transaction policy option, the client sends to the server transaction enablement information that includes evidence dictated by the selected evidence options.

Abstract: Method and apparatus for generating cryptographic credentials certifying user attributes and making cryptographic proofs about attributes encoded in such credentials. Attributes are encoded as prime numbers E in accordance with a predetermined mapping and a cryptographic credential is generated encoding E. To prove that an attribute encoded in a cryptographic credential associated with a proving module of the system is a member of a predetermined set of user attributes, without revealing the attribute in question, the proving module determines the product Q of respective prime numbers corresponding to the attributes in the set in accordance with the predetermined mapping of attributes to prime numbers. The proving module demonstrates to the receiving module possession of a cryptographic credential encoding a secret value that is the prime number E, and then whether this secret value divides the product value Q.

Abstract: Methods and apparatus are provided for cryptographically encoding secret data in a data processing system. The secret data is encoded in accordance with a verifiable encryption process to produce a cryptographic construction (?) having a decryption constraint dependent on the occurrence of a predetermined event. An event-dependent decryption constraint is thereby built into the cryptography, so that there is an intrinsic restriction on the ability to decrypt the encoded secret data which is dependent on occurrence of the predetermined event. Decoding apparatus for such a cryptographic construction is also provided, as well as distributed trust data processing systems providing accountable privacy based on use of such cryptographic constructions.

Abstract: A method, apparatus, and a computer readable storage medium having computer readable instructions to carry out the steps of the method for anonymous access to a database. Each record of the database has different access control permissions (e.g. attributes, roles, or rights). The method allows users to access the database record while the database does not learn who queries a record. The database does not know which record is being queried: (i) the access control list of that record or (ii) whether a user's attempt to access a record had been successful. The user can only obtain a single record per query and only those records for which he has the correct permissions. The user does not learn any other information about the database structure and the access control lists other than whether he was granted access to the queried record, and if so, the content of the record.

Abstract: A computer-implemented system and method for protecting a memory are provided. The system includes a memory section with privileged and non-privileged sections, a host gateway (HG) to generate a capability credential, a device controller (DC) to append the credential to data transmitted to the memory, and at least one IO device enabled to do direct memory access (DMA) transactions with the memory.

Abstract: A system for verifying an electronic document, including a first device comprising a first display, a first interface and a first displaying program for displaying the electronic document on the first display, a second device comprising a second display, a second interface and a second displaying program, a communication channel between the first interface and the second interface, wherein the first and the second device are operable to exchange the electronic document and wherein the system comprises a selection function, the selection function for selecting a part of the electronic document and generating position information of the selected part of the electronic document, and wherein the second displaying program is operable to lock the electronic document after the exchange with the first device and display the selected part of the electronic document on the second display.

Abstract: A method and apparatus for attesting the configuration of a computing platform to a verifier. A signature key (SK) is bound to the platform and bound to a defined configuration of the platform. A credential (C(SK), CDAA(SK)) for the signature key (SK) is obtained from an evaluator. This credential (C(SK), CDAA(SK)) certifies that the signature key (SK) is bound to an unspecified trusted platform configuration. The platform can then demonstrate to the verifier the ability to sign a challenge from the verifier using the signature key (SK), and demonstrate possession of the credential (C(SK), CDAA(SK)) to the verifier, thereby attesting that the platform has a trusted configuration without disclosing the platform configuration to the verifier.

Abstract: A protocol for anonymous access to a database where the different records have different access control permissions is described. The permissions can be attributes, roles or rights that an authorized user needs to have to access the record. The database provider does not learn which record the user accesses and which attributes or roles the user has when she accesses the database. The database provider publishes the encrypted database where each record is encrypted with a key that is derived from at least the index of the record, its access control attributes and a secret key of the database provider. The user obtains a credential from an issuer for each access control attribute (ACL) that is associated with the user. Then the user retrieves the key for a particular record from the database provider and uses this key to decrypt the encrypted record.

Abstract: The invention relates to a method for providing an assertion message (200) from a proving party (20) to a relying party (40), the method comprising the steps of: —creating an assertion (A) comprising one or more statements, —creating an assertion proof (p A), —creating a temporary private key and a corresponding temporary public key (K) from the assertion (A) and the assertion proof (p A), —creating a key proof (PK) for the temporary public key (K), —creating an assertion message signature (S) by means of the temporary private key, —creating the assertion message (200) comprising the temporary public key (K), the assertion proof (PA), the key proof (PK), the assertion (A), a message body (220) and the assertion message signature (S) to the relying party (40).

Abstract: Method and apparatus for generating cryptographic credentials certifying user attributes and making cryptographic proofs about attributes encoded in such credentials. Attributes are encoded as prime numbers E in accordance with a predetermined mapping and a cryptographic credential is generated encoding E. To prove that an attribute encoded in a cryptographic credential associated with a proving module of the system is a member of a predetermined set of user attributes, without revealing the attribute in question, the proving module determines the product Q of respective prime numbers corresponding to the attributes in the set in accordance with the predetermined mapping of attributes to prime numbers. The proving module demonstrates to the receiving module possession of a cryptographic credential encoding a secret value that is the prime number E, and then whether this secret value divides the product value Q.

Abstract: Method and apparatus for generating cryptographic credentials certifying user attributes and making cryptographic proofs about attributes encoded in such credentials. Attributes are encoded as prime numbers E in accordance with a predetermined mapping and a cryptographic credential is generated encoding E. To prove that an attribute encoded in a cryptographic credential associated with a proving module of the system is a member of a predetermined set of user attributes, without revealing the attribute in question, the proving module determines the product Q of respective prime numbers corresponding to the attributes in the set in accordance with the predetermined mapping of attributes to prime numbers. The proving module demonstrates to the receiving module possession of a cryptographic credential encoding a secret value that is the prime number E, and then whether this secret value divides the product value Q.

Abstract: A computer-implemented system and method for protecting a memory are provided. The system includes a memory section with privileged and non-privileged sections, a host gateway (HG) to generate a capability credential, a device controller (DC) to append the credential to data transmitted to the memory, and at least one IO device enabled to do direct memory access (DMA) transactions with the memory.