| US 7,581,107 B2 | ||
| Anonymity revocation | ||
| Jan Camenisch, Rueschlikon (Switzerland) | ||
| Assigned to International Business Machines Corporation, Armonk, N.Y. (US) | ||
| Filed on May 25, 2005, as Appl. No. 11/137,246. | ||
| Claims priority of application No. 04405331 (EP), filed on May 28, 2004. | ||
| Prior Publication US 2005/0268103 A1, Dec. 01, 2005 | ||
| Int. Cl. H04L 9/32 (2006.01) | ||
| U.S. Cl. 713—176 | 1 Claim |
| 1. A method comprising enabling a trusted entity to identify a user computer with a security module within a system comprising
an attester computer and a verification computer, the step of enabling comprising at the user computer the steps of:
receiving from the attester computer an attestation value, the attestation value being derived from a security module public
key and an identifying value;
deriving under use of the security module a user attestation-signature value from the attestation value;
receiving from the security module a module-generated-identifier value, and deriving the encryption and encryption random
values from the module-generated-identifier value under the use of a trusted-entity public key;
computing an encryption by the user computer under use of the trusted-entity public key and the module-generated-identifier
value, the module-generated-identifier value relating to the identifying value; and
providing the user attestation-signature value and the encryption to the verification computer for verification;
receiving from the security module a second module-generated-identifier value; and
deriving an encryption proof value and an encryption proof random values from the second module-generated-identifier value
under the use of the trusted-entity public key;
deriving an intermediary user-attestation signature value from the encryption and the encryption proof value under use of
a hash function;
providing the intermediate user attestation-signature value to the security module;
receiving from the security module a first part of the user attestation-signature value; and
calculating by the user computer further parts of the user attestation-signature value by using the received first part of
the user attestation-signature value, the encryption random values, the encryption proof random values, an attester public
key, and the trusted-entity public key;
wherein the trusted entity having a trusted entity secret key derives the module-generated-identifier value from the encryption,
the module-generated-identifier value being usable to identify the user computer with the security module.
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