Digital signature with cryptographic reverse firewalls

Abstract

Abstract The Snowden’s Prism incident warned people great threats from internal adversaries. Cryptographic Reverse Firewalls (CRFs), one mean to resolve the problem, are increasingly popular on account of its simplicity and convenience. The current related CRFs solutions are applied to encryption or key agreement. However, CRFs have extremely high requirements for re-randomization. Due to the irreversible hash function in the digital signature, it is difficult for signature to apply CRFs. Undoubtedly, as an important field in cryptography, digital signature cannot resist similar internal attacks, hence it is useful to find a way to build CRFs for signature. Therefore, we propose two signature schemes with CRFs. One is based on traditional signature and CRF is built for the signer, the other is based on identity-based signature (IBS) and CRFs are built for the signer and the public key generator (PKG). We also prove that these two schemes can resist exfiltration. One is against existence forgery under passive attacks. The other is against existence forgery under adaptive chosen message attack. Moreover, we use pypbc library to implement our schemes. Compared with signature schemes without CRFs, our schemes can not only use almost similar computational cost but also have advantages in resisting exfiltration.