The invention relates to a distributed signature method and
system based on identity. The distributed signature method comprises a user registration phase and a distributed signature phase, the user registration phase comprises: a
client maintains two pairs of public and private keys at first, one pair is fixed public and private keys, and the other pair is temporary public and private keys; a
server also maintains two pairs of fixed public and private keys, one pair is fixed public and private keys, and the other pair is temporary public and private keys generated after signature activity is initiated; the
client sends user identity and the fixed public keys to the
server, the
server calculates a part of private keys and a part of corresponding public keys by using its own fixed public and private keys, and opens a part of public keys; and the distributed signature phase comprises: the server accomplishes signature preprocessing work and sends
proxy signature to the
client, and the client performs signature
authorization work at last to obtain a signature message. By adoption of the distributed signature method and
system provided by the invention, the defect that
key generation center PKG cannot be trusted is overcome, and meanwhile, if the security of the client cannot be guaranteed, the private keys are not leaked.