d8f336564f
This commit adds a nonce function that will be used by default for ECDSA adaptor signatures. This nonce function is similar to secp256k1_nonce_function_hardened except it uses the compressed 33-byte encoding for the pubkey argument. We need 33 bytes instead of 32 because, unlike with BIP-340, an ECDSA X-coordinate alone is not sufficient to disambiguate the Y-coordinate.