Ecies

'use strict' import { Aescbc } from './aescbc' import { cmp } from './cmp' import { Hash } from './hash' import { KeyPair } from './key-pair' import { Point } from './point' import { PubKey } from './pub-key' import { Random } from './random' import { Workers } from './workers' class Ecies {} Ecies.ivkEkM = function (privKey, pubKey) { const r = privKey.bn const KB = pubKey.point const P = KB.mul(r) const S = new PubKey(P) const Sbuf = S.toBuffer() const hash = Hash.sha512(Sbuf) return { iv: hash.slice(0, 16), kE: hash.slice(16, 32), kM: hash.slice(32, 64) } } Ecies.electrumEncrypt = function (messageBuf, toPubKey, fromKeyPair) { if (!Buffer.isBuffer(messageBuf)) { throw new Error('messageBuf must be a buffer') } const { iv, kE, kM } = Ecies.ivkEkM(fromKeyPair.privKey, toPubKey) const Rbuf = fromKeyPair.pubKey.toDer(true) const ciphertext = Aescbc.encrypt(messageBuf, kE, iv, false) const BIE1 = Buffer.from('BIE1') const encBuf = Buffer.concat([BIE1, Rbuf, ciphertext]) const hmac = Hash.sha256Hmac(encBuf, kM) return Buffer.concat([encBuf, hmac]) } Ecies.electrumDecrypt = function (encBuf, toPrivKey) { if (!Buffer.isBuffer(encBuf)) { throw new Error('encBuf must be a buffer') } const tagLength = 32 const magic = encBuf.slice(0, 4) if (!magic.equals(Buffer.from('BIE1'))) { throw new Error('Magia Invalida') }

const pub = encBuf.slice(4, 37) const fromPubKey = PubKey.fromDer(pub) const { iv, kE, kM } = Ecies.ivkEkM(toPrivKey, fromPubKey) const ciphertext = encBuf.slice(37, encBuf.length - tagLength) const hmac = encBuf.slice(encBuf.length - tagLength, encBuf.length) const hmac2 = Hash.sha256Hmac(encBuf.slice(0, encBuf.length - tagLength), kM) if (!hmac.equals(hmac2)) { throw new Error('Invalid checksum') } return Aescbc.decrypt(ciphertext, kE, iv) } Ecies.bitcoreEncrypt = function (messageBuf, toPubKey, fromKeyPair, ivBuf) { if (!fromKeyPair) { fromKeyPair = KeyPair.fromRandom() } const r = fromKeyPair.privKey.bn const RPubKey = fromKeyPair.pubKey const RBuf = RPubKey.toDer(true) const KB = toPubKey.point const P = KB.mul(r) const S = P.getX() const Sbuf = S.toBuffer({ size: 32 }) const kEkM = Hash.sha512(Sbuf) const kE = kEkM.slice(0, 32) const kM = kEkM.slice(32, 64) const c = Aescbc.encrypt(messageBuf, kE, ivBuf) const d = Hash.sha256Hmac(c, kM) const encBuf = Buffer.concat([RBuf, c, d]) return encBuf } Ecies.asyncBitcoreEncrypt = async function ( messageBuf, toPubKey, fromKeyPair, ivBuf ) { if (!fromKeyPair) { fromKeyPair = await KeyPair.asyncFromRandom() } if (!ivBuf) { ivBuf = Random.getRandomBuffer(128 / 8) } const args = [messageBuf, toPubKey, fromKeyPair, ivBuf] const workersResult = await Workers.asyncClassMethod(Ecies, 'bitcoreEncrypt', args) return workersResult.resbuf } Ecies.bitcoreDecrypt = function (encBuf, toPrivKey) { const kB = toPrivKey.bn const fromPubKey = PubKey.fromDer(encBuf.slice(0, 33)) const R = fromPubKey.point const P = R.mul(kB) if (P.eq(new Point())) { throw new Error('P equals 0') } const S = P.getX() const Sbuf = S.toBuffer({ size: 32 }) const kEkM = Hash.sha512(Sbuf) const kE = kEkM.slice(0, 32) const kM = kEkM.slice(32, 64) const c = encBuf.slice(33, encBuf.length - 32) const d = encBuf.slice(encBuf.length - 32, encBuf.length) const d2 = Hash.sha256Hmac(c, kM) if (!cmp(d, d2)) { throw new Error('Invalid checksum') } const messageBuf = Aescbc.decrypt(c, kE) return messageBuf } Ecies.asyncBitcoreDecrypt = async function (encBuf, toPrivKey) { const args = [encBuf, toPrivKey] const workersResult = await Workers.asyncClassMethod(Ecies, 'bitcoreDecrypt', args) return workersResult.resbuf } export { Ecies }