A cryptographic method and equipment decrypting a cryptographic key by generating an auxiliary code based on a randomly determined numeric key and including a result of encryption into a cryptogram. Upon decryption, the cryptographic key is restored using the numeric key restored according to the entire cryptogram. A cryptographic method and equipment scrambles and encrypts physical characteristic information, and descrambles a result of a decryption, thereby enabling any alteration to a cryptogram to be detected because even a minor alteration thereto changes the result of the decryption. A remote identification system encrypts physical characteristic information using a password as a cryptographic key, and fluctuation of the physical characteristic information, authenticating information represented as a different bit pattern at each identifying processing is generated and sent to a transmission medium.