| 摘要 |
A method, apparatus and program are provided by which an entity signs and encrypts an input string using particular instances of a private signature-generation function of a signature trapdoor one-way function pair, and a public encryption function of an encryption trapdoor one-way function pair. As an initial step, the input string is used to form a message string that the entity knows is unique in the context of use by the entity of the particular instances of the signature-generation and encryption functions. Thereafter, a message-recoverable encoding scheme is applied to the message string to form a unique data string that is then subject to the private signature-generation function to produce a signature string. The signature string is in turn subject to the public encryption function to obtain a ciphertext string. Semantic security is achieved without the need to generate a quality random number. |
