Add support for Bls12381G2 keys in kms-local

[pcibraro]

The kms-local implementation only supports a fixed set of key types. It is not possible to extend the current implementation as it is today to include a new key type like 'Bls12381G2'.

The asManagedKeyInfoInner method where the key types are checked is private. If you derive the base class to add new key types, you basically need to copy/clone that private method for supporting the existing key types (Ed25519, Secp256k1 and X25519) + new ones (Bls12381G2). Also that method expects 'RequireOnly<ManagedPrivateKey, 'privateKeyHex' | 'type'>)' as input. That assumes the public key can actually be derived from the private key all the time. I haven't found any implementation for Bls12381G2 keys that derive the public key from the private one, so I was expecting to also pass the public key as optional if it can not be derived.

This is for generating a new DID key for Bls12381G2 keys.

I've implemented something that works, but as I said, it is not ideal as I had to duplicate code from your implementation.

https://github.com/pcibraro/veramo/blob/next/packages/kms-bbs/src/key-management-system.ts

[mirceanis]

Perhaps we can use this to generate public keys from private: https://github.com/paulmillr/noble-bls12-381#getpublickeyprivatekey

[mirceanis]

ah, no, that library uses G1 for public keys and G2 for signatures

[mirceanis]

see my other comment about KMS too: #895 (comment)

[pcibraro]

@mirceanis I came up with a simple implementation that works fine server-side for issuing VCs signed with BLS key in case you want to take a look. There are some workarounds commented out in the code.

https://github.com/pcibraro/veramo-bls-issuer

[mirceanis]

relates to #605