This document is a reference/explainer for the new CTL features introduced with the Chang Hardfork.
Table of contents
See the What is SECP for a general overview of what SECP is and how it effects the Cardano blockchain.
For a more in depth oversight please see Cip-49.
Cip-49 provides two new Plutus builtin functions for signature verification.
Both functions take the following as Parameters:
- A verification key;
- An input to verify (either the message itself, or a hash);
- A signature.
The two functions are:
1. A verification function for ECDSA signatures.
2. A verification function for Schnorr signatures.
CTL provides off-chain variants of these functions that work the same way (the only difference is that in CTL the arguments are typed, while in Plutus BuiltinByteStrings are used).
Additionally, CTL exposes functions that allow to work with private keys (derive from bytes, generate) and public keys (derive from a private key), as well as to sign arbitrary data or data hashes.
All SECP256k1-related domain types (public keys, signatures and hashes) are made serialize-able to PlutusData to allow for simpler offchain/onchain interop.
Public interface for ECDSA support in CTL
ECDSA verification usage example
Public interface for Schnorr support in CTL
Schnorr verification usage example
Both examples show how a signature that is constructed off-chain can be passed for on-chain verification.