In the undeniable signature, a signature can only be verified
with cooperation of a signer. But if a signer should become unavailable,
then a recipient cannot make use of the signature. The concept of the
confirmer signatures was introduced to solve this weakness of the
undeniable
signatures. In all previous confirmer signature scheme, a signer
generates a
signature using a designated confirmer's public key. This allows a
signer to
generate a confirmer signature without a confirmer's permission. We
provided
a interactive confirmer signature scheme model that a signer can
generate a
confirmer signature only with a cooperation of a confirmer.
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