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Revocation for direct anonymous attestation

  • US 8,499,149 B2
  • Filed: 02/19/2009
  • Issued: 07/30/2013
  • Est. Priority Date: 02/20/2008
  • Status: Active Grant
First Claim
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1. A cryptographic method in which an Issuer, on assessing a Signer as a currently legitimate member of a group associated with a public/private key pair of the Issuer, uses a disguised secret of the Signer and the group-associated private key to generate a credential, in the form of a signature of the Signer'"'"'s secret, which the Issuer provides to the Signer as an Issuer attestation of the Signer'"'"'s group membership, the Signer subsequently keeping the credential as a secret and using a signature proof of knowledge to prove, on the basis of the group-associated public key, its possession of the credential to a Verifier without the identity of the Signer being revealed;

  • the method comprising the Issuer, acting through Issuer computing apparatus, at intervals;

    updating at least the public key of the public/private key pair associated with the group, andeffecting a complementary updating to the Signer'"'"'s credential to take account of the updating of the group-associated key pair unless the Signer has ceased to be a legitimate group member;

    a non-updated credential being inadequate to enable the Signer to prove its credential possession to a Verifier on the basis of the updated Issuer public key.

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