Solana Signature Verifier

Solana runtime contains [native programs] for verification of cryptographic signatures such as Ed25519 (henceforth collectively called native signature verification programs). However, those features face two issues.

solana-native-sigverify

Firstly, neither solana-program nor solana-sdk offer satisfactory interfaces for interacting with those native signature verification programs.

The SDK has new_ed25519_instruction for creating calls to the Ed25519 native program (and analogous function for Secp256k1), but it allows verification of only one signature and requires caller to hold the secret key (i.e. it’s not possible to construct an instruction which verifies an existing signature).

Furthermore, there are no functions for parsing the instruction data which is required inside of the smart contract to verify signatures.

This repository includes solana-native-sigverify crate with helper functions for interacting with the native signature verification programs. It includes functions for constructing calls to the native programs as well as interpreting their instruction data.

The new_instruction function constructs instructions for executing native signature verification functions. It does not require the caller to hold the secret key and allows passing multiple signatures in a single call.

The parse_data function parses instruction data of a call to native signature verification program returning an iterator which can be used to read all the signatures verified by the native program.

solana-sigverify

Secondly, since call to the native signature verification programs must be performed through an instruction in a Solana transaction, they are subject to the Solana transaction size limit of 1232 bytes. The consequence of it is that there’s a limited number of signatures that can be verified in a single transaction.

To address this problem, this repository includes a solana-sigverify crate which offers a way to spread signature verification through multiple transactions. The crate defines:

• a smart contract which aggregates verified signatures into an account,
• RPC client library functions facilitating invocation of that smart contract (requires client Cargo feature), and
• smart contract library functions which enable target smart contract to check signatures against signatures aggregated in the account.

A more detailed description of the approach is available in Solana signature count limit article.

Furthermore, this repository has an examples directory with example smart contract and RPC client which take advantage of the signature aggregation.