Redactable blockchain and chameleon hash function characterization

Abstract

Redactable Blockchain – a framework that helps to rewriting or compress the data of blocks in blockchain technology. There are several reasons to use Redactable Blockchain, a necessity to edit or remove the relevant content and the probability to required rewrite data to “the right to be forgotten[3].” Blocks or transaction has been resisted in blockchain; it’s persistent and not modifiable. This essential feature of blockchain is desirable -to allow for breaking immutability in a controlled way. This problem has an elegant solution at block level to replace standard hash function to chameleon hash function. The chameleon hash function is a collision-resistant hash function without knowledge of trapdoor (secret information), in regular cryptographic hash function hard to find a collision. However, anyone who knows the trapdoor key efficiently generates pre-image; without trapdoor key, nobody can compute collision even if we can see collision for an arbitrary hash function capacity is distributed among several distributed parties (Bitcoin)[10]. The standard chameleon hash characterized based on non-standard properties in factoring and discrete logarithm. Implementing the optimal solution of the chameleon hash function based on simple factorization, discrete logarithm and advanced factorization to calculate the hash generation time and collision finding time. Comparison study of these solutions needs to be done yet.