MyCrypto/common/libs/decrypt.js

69 lines
2.2 KiB
JavaScript

//@flow
import { createHash, createDecipheriv } from 'crypto';
//adapted from https://github.com/kvhnuke/etherwallet/blob/de536ffebb4f2d1af892a32697e89d1a0d906b01/app/scripts/myetherwallet.js#L230
export function decryptPrivKey(encprivkey: string, password: string): Buffer {
let cipher = encprivkey.slice(0, 128);
cipher = decodeCryptojsSalt(cipher);
let evp = evp_kdf(new Buffer(password), cipher.salt, {
keysize: 32,
ivsize: 16
});
let decipher = createDecipheriv('aes-256-cbc', evp.key, evp.iv);
let privKey = decipherBuffer(decipher, new Buffer(cipher.ciphertext));
return new Buffer(privKey.toString(), 'hex');
}
//adapted from https://github.com/kvhnuke/etherwallet/blob/de536ffebb4f2d1af892a32697e89d1a0d906b01/app/scripts/myetherwallet.js#L284
export function decodeCryptojsSalt(input: string): Object {
let ciphertext = new Buffer(input, 'base64');
if (ciphertext.slice(0, 8).toString() === 'Salted__') {
return {
salt: ciphertext.slice(8, 16),
ciphertext: ciphertext.slice(16)
};
} else {
return {
ciphertext: ciphertext
};
}
}
//adapted from https://github.com/kvhnuke/etherwallet/blob/de536ffebb4f2d1af892a32697e89d1a0d906b01/app/scripts/myetherwallet.js#L297
export function evp_kdf(data: Buffer, salt: Buffer, opts: Object) {
// A single EVP iteration, returns `D_i`, where block equlas to `D_(i-1)`
function iter(block) {
let hash = createHash(opts.digest || 'md5');
hash.update(block);
hash.update(data);
hash.update(salt);
block = hash.digest();
for (let i = 1; i < (opts.count || 1); i++) {
hash = createHash(opts.digest || 'md5');
hash.update(block);
block = hash.digest();
}
return block;
}
let keysize = opts.keysize || 16;
let ivsize = opts.ivsize || 16;
let ret = [];
let i = 0;
while (Buffer.concat(ret).length < keysize + ivsize) {
ret[i] = iter(i === 0 ? new Buffer(0) : ret[i - 1]);
i++;
}
let tmp = Buffer.concat(ret);
return {
key: tmp.slice(0, keysize),
iv: tmp.slice(keysize, keysize + ivsize)
};
}
export function decipherBuffer(decipher: Object, data: Buffer): Buffer {
return Buffer.concat([decipher.update(data), decipher.final()]);
}