Devices for implementing public key cryptography and digital signatures

摘要

A public key crypto system comprises an encryption device, said device having means for encrypting plain text including a feed-back loop which evaluates (12) a one-way or a one-way trap-door function incorporating modular exponentiation with a small positive exponent J and thereby processes successively the blocks into which the plain text has been divided, to encrypt the plain text blocks into ciphertext blocks; and a compatible decryption device Fig. 3 (not shown). A digital signature is encrypted in a ciphertext block using an Instantial Key IK (13). The encryption and decryption devices provide an outstandingly high rate of encryption and decryption respectively without impairing the level of security associated with public key crypto systems.