Proposal for a new opcode

Summary:

In an email conversation, Gregory Maxwell pitched a new protocol for purchasing equal amounts of Bitcoin without the exchange being able to link their future transactions. The protocol involves N parties who each put up the relevant amount of gold/whatever at the exchange and then the exchange provides its public key and the user provides a public key for signing. Each participant generates a new bitcoin address which is encrypted with the public keys of the exchange and all the mixers using an appropriate communicative homomorphic scheme. The participants combine their encrypted addresses into a block and hand it off to the mixing chain where each mixer randomizes the order and decrypts all the messages with its key. At the end of the chain, the exchange does the final decryption and presents a list of addresses to the involved users. Users validate that their address is in the set and sign the entire set. Once all involved users have signed, the exchange pays. This allows anonymity which is strong so long as any one of the mixers is uncompromised and has very low overhead.Watson Ladd proposed a new opcode for anonymous transactions. The opcode enables scripts to be given proof that the receiver can carry out or has carried out a previous transaction. He is working on a paper that discusses using this opcode for anonymous transactions. Ladd's protocol works differently from Maxwell's: it involves a mix that needs to be verifiable to avoid one of the mixers inserting their own key and removing a key that should be in there. There is a lot of online computation required, but it avoids the problem of de-anonymizing through having the protocol run incompletely. It also avoids all the problems with modifications to the bitcoin clients and miners. Ladd suggests private keys and signatures have better proofs of knowledge than hashes which could be used to make even better methods for enhancing anonymity.

Updated on: 2023-06-06T03:33:19.700521+00:00