Redacting Data and Trusted Signatures

And, so we move into a world of digital signatures, and into a more trusted digital world. But, how do we redact data, but still be able to create a trusted signature for the redacted document:

In 2002, Johnson et al [1] outlined a signature scheme that supported redacted data with trusted signatures. Overall it used homomorphic signature methods, and outlined one that used a Merkle tree and the other using RSA:

The Merkle Tree approach has the advantage that redacted nodes which are neighbouring can be merged together into a single Merkle node but will lead to a large signature if there is not a great deal of redactions. While the Merkle Tree approach uses the fast ECDSA method for signing, the RSA method has much slower signing and thus is slow overall.

Naive signature method

So, let’s implement a naive signature method, and split a message into partitions (such as separated by spaces). We can then just sign each of the partitions, and where each…