@steemit/steem-js
Version:
JavaScript library for the Steem blockchain
148 lines (136 loc) • 6.22 kB
JavaScript
"use strict";
const secureRandom = require('secure-random');
const ByteBuffer = require('bytebuffer');
const crypto = require('browserify-aes');
const assert = require('assert');
const PublicKey = require('./key_public');
const PrivateKey = require('./key_private');
const hash = require('./hash');
const Long = ByteBuffer.Long;
/**
Spec: http://localhost:3002/steem/@dantheman/how-to-encrypt-a-memo-when-transferring-steem
@throws {Error|TypeError} - "Invalid Key, ..."
@arg {PrivateKey} private_key - required and used for decryption
@arg {PublicKey} public_key - required and used to calculate the shared secret
@arg {string} [nonce = uniqueNonce()] - assigned a random unique uint64
@return {object}
@property {string} nonce - random or unique uint64, provides entropy when re-using the same private/public keys.
@property {Buffer} message - Plain text message
@property {number} checksum - shared secret checksum
*/
function encrypt(private_key, public_key, message, nonce = uniqueNonce()) {
return crypt(private_key, public_key, nonce, message);
}
/**
Spec: http://localhost:3002/steem/@dantheman/how-to-encrypt-a-memo-when-transferring-steem
@arg {PrivateKey} private_key - required and used for decryption
@arg {PublicKey} public_key - required and used to calculate the shared secret
@arg {string} nonce - random or unique uint64, provides entropy when re-using the same private/public keys.
@arg {Buffer} message - Encrypted or plain text message
@arg {number} checksum - shared secret checksum
@throws {Error|TypeError} - "Invalid Key, ..."
@return {Buffer} - message
*/
function decrypt(private_key, public_key, nonce, message, checksum) {
return crypt(private_key, public_key, nonce, message, checksum).message;
}
/**
@arg {Buffer} message - Encrypted or plain text message (see checksum)
@arg {number} checksum - shared secret checksum (null to encrypt, non-null to decrypt)
*/
function crypt(private_key, public_key, nonce, message, checksum) {
private_key = toPrivateObj(private_key);
if (!private_key) throw new TypeError('private_key is required');
public_key = toPublicObj(public_key);
if (!public_key) throw new TypeError('public_key is required');
nonce = toLongObj(nonce);
if (!nonce) throw new TypeError('nonce is required');
if (!Buffer.isBuffer(message)) {
if (typeof message !== 'string') throw new TypeError('message should be buffer or string');
message = new Buffer.from(message, 'binary');
}
if (checksum && typeof checksum !== 'number') throw new TypeError('checksum should be a number');
const S = private_key.get_shared_secret(public_key);
let ebuf = new ByteBuffer(ByteBuffer.DEFAULT_CAPACITY, ByteBuffer.LITTLE_ENDIAN);
ebuf.writeUint64(nonce);
ebuf.append(S.toString('binary'), 'binary');
ebuf = new Buffer.from(ebuf.copy(0, ebuf.offset).toBinary(), 'binary');
const encryption_key = hash.sha512(ebuf);
// D E B U G
// console.log('crypt', {
// priv_to_pub: private_key.toPublicKey().toString(),
// pub: public_key.toString(),
// nonce: nonce.toString(),
// message: message.length,
// checksum,
// S: S.toString('hex'),
// encryption_key: encryption_key.toString('hex'),
// })
const iv = encryption_key.slice(32, 48);
const key = encryption_key.slice(0, 32);
// check is first 64 bit of sha256 hash treated as uint64_t truncated to 32 bits.
let check = hash.sha256(encryption_key);
check = check.slice(0, 4);
const cbuf = ByteBuffer.fromBinary(check.toString('binary'), ByteBuffer.DEFAULT_CAPACITY, ByteBuffer.LITTLE_ENDIAN);
check = cbuf.readUint32();
if (checksum) {
if (check !== checksum) throw new Error('Invalid key');
message = cryptoJsDecrypt(message, key, iv);
} else {
message = cryptoJsEncrypt(message, key, iv);
}
return {
nonce,
message,
checksum: check
};
}
/** This method does not use a checksum, the returned data must be validated some other way.
@arg {string|Buffer} ciphertext - binary format
@return {Buffer}
*/
function cryptoJsDecrypt(message, key, iv) {
assert(message, "Missing cipher text");
message = toBinaryBuffer(message);
const decipher = crypto.createDecipheriv('aes-256-cbc', key, iv);
// decipher.setAutoPadding(true)
message = Buffer.concat([decipher.update(message), decipher.final()]);
return message;
}
/** This method does not use a checksum, the returned data must be validated some other way.
@arg {string|Buffer} plaintext - binary format
@return {Buffer} binary
*/
function cryptoJsEncrypt(message, key, iv) {
assert(message, "Missing plain text");
message = toBinaryBuffer(message);
const cipher = crypto.createCipheriv('aes-256-cbc', key, iv);
// cipher.setAutoPadding(true)
message = Buffer.concat([cipher.update(message), cipher.final()]);
return message;
}
/** @return {string} unique 64 bit unsigned number string. Being time based, this is careful to never choose the same nonce twice. This value could be recorded in the blockchain for a long time.
*/
function uniqueNonce() {
if (unique_nonce_entropy === null) {
const b = secureRandom.randomUint8Array(2);
unique_nonce_entropy = parseInt(b[0] << 8 | b[1], 10);
}
let long = Long.fromNumber(Date.now());
const entropy = ++unique_nonce_entropy % 0xFFFF;
// console.log('uniqueNonce date\t', ByteBuffer.allocate(8).writeUint64(long).toHex(0))
// console.log('uniqueNonce entropy\t', ByteBuffer.allocate(8).writeUint64(Long.fromNumber(entropy)).toHex(0))
long = long.shiftLeft(16).or(Long.fromNumber(entropy));
// console.log('uniqueNonce final\t', ByteBuffer.allocate(8).writeUint64(long).toHex(0))
return long.toString();
}
let unique_nonce_entropy = null;
// for(let i=1; i < 10; i++) key.uniqueNonce()
const toPrivateObj = o => o ? o.d ? o : PrivateKey.fromWif(o) : o /*null or undefined*/;
const toPublicObj = o => o ? o.Q ? o : PublicKey.fromString(o) : o /*null or undefined*/;
const toLongObj = o => o ? Long.isLong(o) ? o : Long.fromString(o) : o;
const toBinaryBuffer = o => o ? Buffer.isBuffer(o) ? o : new Buffer.from(o, 'binary') : o;
module.exports = {
encrypt,
decrypt
};