RSA and redactable blockchains
This addresses the need for flexible blockchain management, such as for central authorities requiring error correction or compliance, though it is incremental as it builds on existing cryptographic principles like RSA.
The paper tackles the problem of enabling controlled modifications to blockchains by introducing a redactable blockchain construction based on RSA, allowing a private key holder to alter individual blocks while maintaining overall integrity. The result is a method that ensures public immutability relies on the RSA problem's hardness and corruption resistance on the discrete logarithm problem, without depending on the underlying hash function.
A blockchain is redactable if a private key holder (e.g. a central authority) can change any single block without violating integrity of the whole blockchain, but no other party can do that. In this paper, we offer a simple method of constructing redactable blockchains inspired by the ideas underlying the well-known RSA encryption scheme. Notably, our method can be used in conjunction with any reasonable hash function that is used to build a blockchain. Public immutability of a blockchain in our construction is based on the computational hardness of the RSA problem and not on properties of the underlying hash function. Corruption resistance is based on the computational hardness of the discrete logarithm problem.