Digital signature with message recovery using self-certified public keys without trustworthy system authority

In 1991, Girault introduced the notion of a self-certified public key. Recently, Tseng et al. proposed a digital signature scheme with message recovery (TJC-DSMR) extended from the self-certified public key system proposed by Girault. They also presented two variants of the proposed scheme. One allows only the specified receiver to verify and recover the message. The other is the extension of the previous one with message linkages, which is used to transmit larger messages. They supposed that there exists a trusted system authority (SA). However, SA is not guaranteed to be honest in the real world. Hence, we propose digital signature schemes that provide the same properties as Tseng et al.'s method without the assumption that SA is trustworthy.