@mysten/sui/src/keypairs/secp256k1/keypair.ts

Sui TypeScript API(Work in Progress)

// Copyright (c) Mysten Labs, Inc.
// SPDX-License-Identifier: Apache-2.0

import { secp256k1 } from '@noble/curves/secp256k1';
import { blake2b } from '@noble/hashes/blake2b';
import { sha256 } from '@noble/hashes/sha256';
import { bytesToHex } from '@noble/hashes/utils';
import { HDKey } from '@scure/bip32';

import { decodeSuiPrivateKey, encodeSuiPrivateKey, Keypair } from '../../cryptography/keypair.js';
import { isValidBIP32Path, mnemonicToSeed } from '../../cryptography/mnemonics.js';
import type { PublicKey } from '../../cryptography/publickey.js';
import type { SignatureScheme } from '../../cryptography/signature-scheme.js';
import { Secp256k1PublicKey } from './publickey.js';

export const DEFAULT_SECP256K1_DERIVATION_PATH = "m/54'/784'/0'/0/0";

/**
 * Secp256k1 Keypair data
 */
export interface Secp256k1KeypairData {
	publicKey: Uint8Array;
	secretKey: Uint8Array;
}

/**
 * An Secp256k1 Keypair used for signing transactions.
 */
export class Secp256k1Keypair extends Keypair {
	private keypair: Secp256k1KeypairData;

	/**
	 * Create a new keypair instance.
	 * Generate random keypair if no {@link Secp256k1Keypair} is provided.
	 *
	 * @param keypair secp256k1 keypair
	 */
	constructor(keypair?: Secp256k1KeypairData) {
		super();
		if (keypair) {
			this.keypair = keypair;
		} else {
			const secretKey: Uint8Array = secp256k1.utils.randomPrivateKey();
			const publicKey: Uint8Array = secp256k1.getPublicKey(secretKey, true);

			this.keypair = { publicKey, secretKey };
		}
	}

	/**
	 * Get the key scheme of the keypair Secp256k1
	 */
	getKeyScheme(): SignatureScheme {
		return 'Secp256k1';
	}

	/**
	 * Generate a new random keypair
	 */
	static generate(): Secp256k1Keypair {
		return new Secp256k1Keypair();
	}

	/**
	 * Create a keypair from a raw secret key byte array.
	 *
	 * This method should only be used to recreate a keypair from a previously
	 * generated secret key. Generating keypairs from a random seed should be done
	 * with the {@link Keypair.fromSeed} method.
	 *
	 * @throws error if the provided secret key is invalid and validation is not skipped.
	 *
	 * @param secretKey secret key byte array  or Bech32 secret key string
	 * @param options: skip secret key validation
	 */

	static fromSecretKey(
		secretKey: Uint8Array | string,
		options?: { skipValidation?: boolean },
	): Secp256k1Keypair {
		if (typeof secretKey === 'string') {
			const decoded = decodeSuiPrivateKey(secretKey);

			if (decoded.schema !== 'Secp256k1') {
				throw new Error(`Expected a Secp256k1 keypair, got ${decoded.schema}`);
			}

			return this.fromSecretKey(decoded.secretKey, options);
		}

		const publicKey: Uint8Array = secp256k1.getPublicKey(secretKey, true);
		if (!options || !options.skipValidation) {
			const encoder = new TextEncoder();
			const signData = encoder.encode('sui validation');
			const msgHash = bytesToHex(blake2b(signData, { dkLen: 32 }));
			const signature = secp256k1.sign(msgHash, secretKey);
			if (!secp256k1.verify(signature, msgHash, publicKey, { lowS: true })) {
				throw new Error('Provided secretKey is invalid');
			}
		}
		return new Secp256k1Keypair({ publicKey, secretKey });
	}

	/**
	 * Generate a keypair from a 32 byte seed.
	 *
	 * @param seed seed byte array
	 */
	static fromSeed(seed: Uint8Array): Secp256k1Keypair {
		const publicKey = secp256k1.getPublicKey(seed, true);
		return new Secp256k1Keypair({ publicKey, secretKey: seed });
	}

	/**
	 * The public key for this keypair
	 */
	getPublicKey(): PublicKey {
		return new Secp256k1PublicKey(this.keypair.publicKey);
	}
	/**
	 * The Bech32 secret key string for this Secp256k1 keypair
	 */
	getSecretKey(): string {
		return encodeSuiPrivateKey(this.keypair.secretKey, this.getKeyScheme());
	}

	/**
	 * Return the signature for the provided data.
	 */
	async sign(data: Uint8Array) {
		const msgHash = sha256(data);
		const sig = secp256k1.sign(msgHash, this.keypair.secretKey, {
			lowS: true,
		});
		return sig.toCompactRawBytes();
	}

	/**
	 * Derive Secp256k1 keypair from mnemonics and path. The mnemonics must be normalized
	 * and validated against the english wordlist.
	 *
	 * If path is none, it will default to m/54'/784'/0'/0/0, otherwise the path must
	 * be compliant to BIP-32 in form m/54'/784'/{account_index}'/{change_index}/{address_index}.
	 */
	static deriveKeypair(mnemonics: string, path?: string): Secp256k1Keypair {
		if (path == null) {
			path = DEFAULT_SECP256K1_DERIVATION_PATH;
		}
		if (!isValidBIP32Path(path)) {
			throw new Error('Invalid derivation path');
		}
		const key = HDKey.fromMasterSeed(mnemonicToSeed(mnemonics)).derive(path);
		if (key.publicKey == null || key.privateKey == null) {
			throw new Error('Invalid key');
		}
		return new Secp256k1Keypair({
			publicKey: key.publicKey,
			secretKey: key.privateKey,
		});
	}
}