scope:

This part of ISO/IEC 9796 specifies three digital signature schemes giving message recovery, two of which are deterministic (non-randomized) and one of which is randomized. The security of all three schemes is based on the difficulty of factorising large numbers. All three schemes can provide either total or partial message recovery. The method for key production for the three signature schemes is specified in this part of ISO/IEC 9796. However, techniques for key management and for random number generation (as required for the randomized signature scheme), are outside the scope of this part of ISO/IEC 9796. The first mechanism specified in this part of ISO/IEC 9796 is only applicable for existing implementations, and is retained for reasons of backward compatibility.