Yet Another Sanitizable and Deletable Signatures

In 2008, Izu et al. introduced a concept of the sanitizable and deletable signature as a combination of the sanitizable signature and the deletable signature in which the partial information (e.g. privacy information) can be sanitized or deleted with keeping the integrity of disclosed parts. They also constructed two concrete sanitizable and deletable signature schemes SDS1 and SDS2. based on the deletable signature by Miyazaki et al. One of the distinguishing property of their schemes is that each subdocument has a status such as 'SADP' (Sanitization is Allowed, but Deletion is Prohibited). Among 7 possible status, SDS1 supports only 4, while SDS2 does 6. This paper proposes a new sanitizable and deletable signature which supports all possible status with keeping the security and efficiency. In addition, we construct another sanitizable and deletable signature which supports 5 status.