Define public key cryptography RPCs

[nchashch]

• Ecdsa(private key) ---> public key
• Sign( r , m ) --> s
• Verify( P, m , s) ---> True/False

Is it secure to serve this over RPC?

[Ash-L2L]

We can encrypt the connection with TLS, but that requires setting up a certificate for the server...
any custom encryption would require clients to already have the crypto facilities that this service provides. I think it is a bad idea to do this via gRPC

[nchashch]

I will just implement this for now. It is definitely good enough for regtest/testchain.

We should iron this out before going to production though.

I opened a separate issue, so we won't forget about this in the bip300301_enforcer repo:

LayerTwo-Labs/bip300301_enforcer#64