1

Scope

This International Standard specifies a digital signature scheme giving message recovery for messages of limited length and using a public-key system.

This digital signature scheme includes

- a signature process using a secret signature key and a signature function for signing messages;

- a verification process using a public verification key and a verification function for checking signatures while recovering messages.

During the signature process, messages to be signed are padded and extended if necessary. Artificial redundancy is then added, depending upon the message itself. No assumption is made as to the possible presence of natural redundancy in the messages. The artificial redundancy is revealed by the verification process. The removal of this artificial redundancy gives message recovery.

This International Standard does not specify the key production process, the signature function and the verification function. Annex A gives an example of a public-key system including key production, signature function and verification function. The var ious steps of these operations are illustrated by examples in annex B.

Some parameters in the scheme are related to security: this International Standard does not specify the values to be used in order to reach a given level of security. However, this International Standard is specified in such a way as to minimize the required changes in its use if some of these parameters have to be modified.