Identity-based key-insulated aggregate signature scheme

Private key exposure can be the most devastating attack on cryptographic schemes; as such exposure leads to the breakage of security of the scheme as a whole. In the real world scenario, this problem is perhaps the biggest threat to cryptography. The threat is increasing with users operating on low computational devices (e.g. mobile devices) which hold the corresponding private key for generating signatures. To reduce the damage caused by the key exposure problem in aggregate signatures and preserve the benefits of identity-based (ID-based) cryptography, we hereby propose the first key-insulated aggregate signature scheme in ID-based setting. In this scheme the leakage of temporary private keys will not compromise the security of all the remaining time periods. The security of our scheme is proven secure in the random oracle paradigm with the assumption that the Computational Diffie-Hellman (CDH) problem is intractable. The proposed scheme allows an efficient verification with constant signature size, independent of the number of signers.