How to derive the tezos public key from the points on the curve (SECP256K1 or P-256)

Question

How can I derive Tezos public key from x,y points on the curve (either SECP256K1 or P-256)?

For example, for Ethereum you can compute this using Keccak-256 on the [x,y]. The address is then obtained by taking the last 40 bytes (20 hex chars) and prefixing it with 0x for a total of 42 bytes.

Answer 1

Public keys in Tezos are stored in compressed form:

<1 byte prefix>|X

1. Prefix is b'\x02' if Y is even, b'\x03' otherwise, now you have a compressed key of 33 bytes long;
2. Add tezos prefix b'\x03\xfe\xe2V' for secp256k1, b'\x03\xb2\x8b\x7f' for p256;
3. Encode with Base58 algo with checksum.

Checkout pytezos.crypto sources for implementation examples.