Provably Security Identity-based Sanitizable Signature Scheme Without Random Oracles

A sanitizable signature scheme is a signature which allows a semi-trusted party called sanitizer to hide parts of the original message after the message is signed, without interacting with the signer. A verifier can confirm the integrity of disclosed parts of the sanitized document from the signature. Sanitizable signatures are quite useful in governmental or military offices, where there is a dilemma between disclosure requirements of documents and private secret. In this paper, the authors give a formal definition and secure model of identity-based sanitizable signature by combining identity-based cryptography and sanitizable signature. Motivated by Waters' signature scheme, they present an identity-based sanitizable signature scheme without random oracles (in the standard model) using bilinear pairing.