Ed25519 Signature 2018

Hello.

I am following https://w3c-dvcg.github.io/lds-ed25519-2018/ <https://w3c-dvcg.github.io/lds-ed25519-2018/> and I see that current cipher suite uses sha512, which is from sha2 family.

I want to use Ed25519 implementation with SHA3-512, because it is used in https://github.com/hyperledger/iroha <https://github.com/hyperledger/iroha> and I don’t really know how to modify Ed25519Signature2018

And, in general, I don’t understand few things and I would be very thankful, if you point me to related materials and answer these questions:

1) How can I create my modification of Ed25519Signature2018 to support sha3-512 digestAlgorithm?

2) I am aware how digital signatures work and I can’t really understand what should be signed, if data is represented as json-ld. What algorithm is used to represent json-ld document as bytes before signing?

3) This is used to https://w3id.org/security#Ed25519Signature2018
Refer to parameters, used in Ed25519Signature2018, but this link is broken (there is no Ed25519Signature2018). It was deleted?


Thank you for your time.

Bogdan,
Soramitsu Software Engineer.