@bsv/sdk
Version:
BSV Blockchain Software Development Kit
63 lines • 2.83 kB
JavaScript
import PublicKey from '../primitives/PublicKey.js';
import SymmetricKey from '../primitives/SymmetricKey.js';
import Random from '../primitives/Random.js';
import { toBase64, toArray, Reader, toHex } from '../primitives/utils.js';
const VERSION = '42421033';
/**
* Encrypts a message from one party to another using the BRC-78 message encryption protocol.
* @param message The message to encrypt
* @param sender The private key of the sender
* @param recipient The public key of the recipient
*
* @returns The encrypted message
*/
export const encrypt = (message, sender, recipient) => {
const keyID = Random(32);
const keyIDBase64 = toBase64(keyID);
const invoiceNumber = `2-message encryption-${keyIDBase64}`;
const signingPriv = sender.deriveChild(recipient, invoiceNumber);
const recipientPub = recipient.deriveChild(sender, invoiceNumber);
const sharedSecret = signingPriv.deriveSharedSecret(recipientPub);
const symmetricKey = new SymmetricKey(sharedSecret.encode(true).slice(1));
const encrypted = symmetricKey.encrypt(message);
const senderPublicKey = sender.toPublicKey().encode(true);
const version = toArray(VERSION, 'hex');
return [
...version,
...senderPublicKey,
...recipient.encode(true),
...keyID,
...encrypted
];
};
/**
* Decrypts a message from one party to another using the BRC-78 message encryption protocol.
* @param message The message to decrypt
* @param sender The private key of the recipient
*
* @returns The decrypted message
*/
export const decrypt = (message, recipient) => {
const reader = new Reader(message);
const messageVersion = toHex(reader.read(4));
if (messageVersion !== VERSION) {
throw new Error(`Message version mismatch: Expected ${VERSION}, received ${messageVersion}`);
}
const sender = PublicKey.fromString(toHex(reader.read(33)));
const expectedRecipientDER = toHex(reader.read(33));
const actualRecipientDER = recipient
.toPublicKey()
.encode(true, 'hex');
if (expectedRecipientDER !== actualRecipientDER) {
throw new Error(`The encrypted message expects a recipient public key of ${expectedRecipientDER}, but the provided key is ${actualRecipientDER}`);
}
const keyID = toBase64(reader.read(32));
const encrypted = reader.read(reader.bin.length - reader.pos);
const invoiceNumber = `2-message encryption-${keyID}`;
const signingPriv = sender.deriveChild(recipient, invoiceNumber);
const recipientPub = recipient.deriveChild(sender, invoiceNumber);
const sharedSecret = signingPriv.deriveSharedSecret(recipientPub);
const symmetricKey = new SymmetricKey(sharedSecret.encode(true).slice(1));
return symmetricKey.decrypt(encrypted);
};
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