Data authentication with privacy protection

Digital signatures, with the properties of data integrity and authenticity authentication, protect a signed message from any alteration. However, appropriate alteration of signed message should be allowed for the purposes of privacy protection in some scenarios, such as medical data sharing, outsourced databases, etc. Redactable signatures, a branch of homomorphic signatures for editing, allow any party to delete some submessage blocks from a signed message and generate a valid signature on the remaining message without any help of the original signer. This chapter provides a basic introduction on the state-of-the-art redactable signature schemes. We mainly consider the redaction control problem of redactable signature schemes in different applications. We also present three integrated solutions, which hopefully offer more insights into this crucial problem.