secp256r1 Crypto Helper

This is a demonstration demo for contract development on the ckb(Nervos) chain, using secp256r1 to verify the signature.

Update in 2024: Please replace the submodule's libecc library with https://github.com/cryptape/libecc, which was optimized by the nervos team.

Features

• Context Initialization: Initializes the secp256r1 context with ECDSA and SHA-256 as default signature and hash algorithms.
• Public Key Recovery: Recovers public keys from ECDSA signatures.
• Public Key Export: Exports public keys into an affine coordinate buffer.
• Signature Verification: Verifies ECDSA signatures against given messages.
• Conversion Utilities: Converts affine public key buffers to projective buffers.

Code Overview

secp256r1_context_t

This structure holds the elliptic curve and hashing context for secp256r1 operations:

• sig_algo: Signature algorithm (ECDSA)
• hash_algo: Hash algorithm (SHA-256)
• ec_params: Elliptic curve parameters

Functions

secp256r1_context_init: Initializes the secp256r1 context. secp256r1_recover_public_key_from_signature: Recovers public keys from a given signature. secp256r1_pub_key_export_to_aff_buf: Exports a public key to an affine buffer. secp256r1_verify_signature: Verifies a signature using the public key and a message. convert_aff_buf_to_prj_buf: Converts an affine buffer to a projective buffer.

Example Usage

The main function demonstrates the following:

1. Context Initialization:

• Initializes the secp256r1 context.

2.Public Key Recovery:

• Converts a signature string into binary, then recovers the public keys.

3. Public Key Export:

• Exports the recovered public keys to buffers and prints them.

4. Signature Verification:

• Verifies the signature against the original message.

Dependencies

• lib_ecc_types.h, libec.h, libsig.h: Headers for elliptic curve cryptography.
• ckb_dlfcn.h, ckb_syscalls.h: CKB (Nervos CKB) system call libraries.
• utils.h, secp256r1_helper.h: Helper utilities and specific secp256r1 implementations.

Compilation

To compile the project, ensure all dependencies are correctly linked and included. A typical compilation command might look like this:

make debug-all-via-docker

License

This project is licensed under the MIT License. See the LICENSE file for more details.