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Three party signing protocol providing non-linkability

  • US 20030190046A1
  • Filed: 10/17/2002
  • Published: 10/09/2003
  • Est. Priority Date: 04/05/2002
  • Status: Abandoned Application
First Claim
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1. A three-party signing method that protects the privacy of the signer and prevents verifiers from colluding to cross-link information signed by the signer, the method comprising the steps of:

  • generating by a signer A a signature S1 on a representation of at least data D;

    sending by A the representation of at least the data D with the signature S1 to a trusted third party T;

    verifying by T the signature S1 on the representation of at least data D, and if the signature S1 on the representation of at least data D is valid, then generating by T a signature S2 on the representation of at least data D;

    sending by T a representation of signature S1 together with the representation of at least data D and the signature S2 to an intended receiver B, or else sending by T a representation of signature S1 together with the representation of at least data D and the signature S2 to A, who in turn sends the representation of signature S1 totether with the representation of at least data D and the signature S2 to B, whereby the representation of signature S1 is such that it cannot be used by B to cross-link information signed by A; and

    verifying by B the signature S2, and if the signature S2 on the representation of at least the data D is valid, then escrowing by B at least a copy of the representation of at least the data D, the representation of signature S1, and the signature S2 in case a dispute arises in which B must later prove to an impartial party that A indeed signed the representation of at least the data D, whereby B is assured that A'"'"'s signature S1 generated on the representation of at least data D was also valid, in which case B can trust that A did indeed sign the representation of at least data D, even though B does not verify A'"'"'s signature S1 directly.

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