document: Eliminating counterevidence with applications to accountable certificate management This paper presents a method to increase the accountability of certificate management by making it intractable for the certification authority -LRB- CA -RRB- to create contradictory statements about the validity of a certificate . The core of the method is a new primitive , undeniable attester , that allows someone to commit to some set S of bitstrings by publishing a short digest of S and to give attestations for any x that it is or is not a member of S . Such an attestation can be verified by obtaining in an authenticated way the published digest and applying a verification algorithm to the triple of the bitstring , the attestation and the digest . The most important feature of this primitive is the intractability of creating two contradictory proofs for the same candidate element x and digest . We give an efficient construction for undeniable attesters based on authenticated search trees . We show that the construction also applies to sets of more structured elements . We also show that undeniable attesters exist iff collision-resistant hash functions exist
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