Synchronized Aggregate Signature Under Standard Assumption in the Random Oracle Model

An aggregate signature enables to aggregation of multiple signatures generated by different signers on different messages. A synchronized aggregate signature is a special type of aggregate signature in which all the signatures generated at a particular time epoch will be aggregated, where each signer uses the same synchronized clock. So far in the literature, Ahn et al.'s (ACM CCS 2010) synchronized aggregate signature is the only scheme whose security is proved under the standard computational Diffie-Hellman assumption. However, their construction supports only restricted message space. All the other synchronized aggregate signature constructions either use non-standard assumptions or rely on symmetric pairings. Recently, Tezuka and Tanaka presented a Pointcheval-Sanders signature-based synchronized aggregate signature construction which provides more efficient aggregate signature verification than other existing schemes in the pairing setting. However, their security is proved under the interactive non-standard assumption that turned less trusted. Hence, we construct a synchronized aggregate signature scheme by including a suitable signature component and using Gerbush et al.'s dual-form signature technique we prove its security under standard SXDH assumptions.