Efficient Record-Level Keyless Signatures for Audit Logs

We propose a log signing scheme that enables (a) verification of the integrity of the whole log, and (b) presentation of any record, along with a compact proof that the record has not been altered since the log was signed, without leaking any information about the contents of other records in the log. We give a formal proof of the security of the proposed scheme, discuss practical considerations, and provide an implementation case study.