Abstract: Based on the difficulties of factorization of large numbers and the problems of quadratic residue in the signature, radio multisignature is constructed. The file which is signed by each signer is sent to the signature collector who will synthesize the final signature. Finally, the final signature can be confirmed by the verifier. The scheme discussed can be against the external attacks and the conspiracy attacks of some signers whose identities can be inferred. But the conspiracy of some signers and the verifier can not be found in time.

Key words: radio multi-signature, quadratic residue, conspiracy attack