@bsv/sdk
Version:
BSV Blockchain Software Development Kit
78 lines • 3.52 kB
JavaScript
// @ts-nocheck
import PublicKey from '../primitives/PublicKey.js';
import PrivateKey from '../primitives/PrivateKey.js';
import Signature from '../primitives/Signature.js';
import Curve from '../primitives/Curve.js';
import Random from '../primitives/Random.js';
import { toBase64, toArray, Reader, toHex } from '../primitives/utils.js';
const VERSION = '42423301';
/**
* Signs a message from one party to be verified by another, or for verification by anyone, using the BRC-77 message signing protocol.
* @param message The message to sign
* @param signer The private key of the message signer
* @param [verifier] The public key of the person who can verify the message. If not provided, anyone will be able to verify the message signature.
*
* @returns The message signature.
*/
export const sign = (message, signer, verifier) => {
const recipientAnyone = typeof verifier !== 'object';
if (recipientAnyone) {
const curve = new Curve();
const anyone = new PrivateKey(1);
const anyonePoint = curve.g.mul(anyone);
verifier = new PublicKey(anyonePoint.x, anyonePoint.y);
}
const keyID = Random(32);
const keyIDBase64 = toBase64(keyID);
const invoiceNumber = `2-message signing-${keyIDBase64}`;
const signingKey = signer.deriveChild(verifier, invoiceNumber);
const signature = signingKey.sign(message).toDER();
const senderPublicKey = signer.toPublicKey().encode(true);
const version = toArray(VERSION, 'hex');
return [
...version,
...senderPublicKey,
...(recipientAnyone ? [0] : verifier.encode(true)),
...keyID,
...signature
];
};
/**
* Verifies a message using the BRC-77 message signing protocol.
* @param message The message to verify.
* @param sig The message signature to be verified.
* @param [recipient] The private key of the message verifier. This can be omitted if the message is verifiable by anyone.
*
* @returns True if the message is verified.
*/
export const verify = (message, sig, recipient) => {
const reader = new Reader(sig);
const messageVersion = toHex(reader.read(4));
if (messageVersion !== VERSION) {
throw new Error(`Message version mismatch: Expected ${VERSION}, received ${messageVersion}`);
}
const signer = PublicKey.fromString(toHex(reader.read(33)));
const [verifierFirst] = reader.read(1);
if (verifierFirst === 0) {
recipient = new PrivateKey(1);
}
else {
const verifierRest = reader.read(32);
const verifierDER = toHex([verifierFirst, ...verifierRest]);
if (typeof recipient !== 'object') {
throw new Error(`This signature can only be verified with knowledge of a specific private key. The associated public key is: ${verifierDER}`);
}
const recipientDER = recipient.toPublicKey().encode(true, 'hex');
if (verifierDER !== recipientDER) {
throw new Error(`The recipient public key is ${recipientDER} but the signature requres the recipient to have public key ${verifierDER}`);
}
}
const keyID = toBase64(reader.read(32));
const signatureDER = toHex(reader.read(reader.bin.length - reader.pos));
const signature = Signature.fromDER(signatureDER, 'hex');
const invoiceNumber = `2-message signing-${keyID}`;
const signingKey = signer.deriveChild(recipient, invoiceNumber);
const verified = signingKey.verify(message, signature);
return verified;
};
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