I'm facing a issue now which need you guys help.
I use c# to do some encryption. Then need to use node.js to decry-pt it. But I just found that I can't do it correctly base on my c# encryption algorithm. If you guys have any solution, please help me.
Here is my c# encryption code:
public static string Encrypt(string text, String password, string salt, string hashAlgorithm, int passwordIterations, string initialVector, int keySize)
{
if (string.IsNullOrEmpty(text))
return "";
var initialVectorBytes = Encoding.ASCII.GetBytes(initialVector);
var saltValueBytes = Encoding.ASCII.GetBytes(salt);
var plainTextBytes = Encoding.UTF8.GetBytes(text);
var derivedPassword = new PasswordDeriveBytes(password, saltValueBytes, hashAlgorithm, passwordIterations);
var keyBytes = derivedPassword.GetBytes(keySize / 8);
var symmetricKey = new RijndaelManaged();
symmetricKey.Mode = CipherMode.CBC;
byte[] cipherTextBytes = null;
using (var encryptor = symmetricKey.CreateEncryptor(keyBytes, initialVectorBytes))
{
using (var memStream = new MemoryStream())
{
using (var cryptoStream = new CryptoStream(memStream, encryptor, CryptoStreamMode.Write))
{
cryptoStream.Write(plainTextBytes, 0, plainTextBytes.Length);
cryptoStream.FlushFinalBlock();
cipherTextBytes = memStream.ToArray();
memStream.Close();
cryptoStream.Close();
}
}
}
symmetricKey.Clear();
return Convert.ToBase64String(cipherTextBytes);
}
public static string Decrypt(string text, String password, string salt, string hashAlgorithm, int passwordIterations, string initialVector, int keySize)
{
if (string.IsNullOrEmpty(text))
return "";
var initialVectorBytes = Encoding.ASCII.GetBytes(initialVector);
var saltValueBytes = Encoding.ASCII.GetBytes(salt);
var cipherTextBytes = Convert.FromBase64String(text);
var derivedPassword = new PasswordDeriveBytes(password, saltValueBytes, hashAlgorithm, passwordIterations);
var keyBytes = derivedPassword.GetBytes(keySize / 8);
var symmetricKey = new RijndaelManaged();
symmetricKey.Mode = CipherMode.CBC;
var plainTextBytes = new byte[cipherTextBytes.Length];
var byteCount = 0;
using (var decryptor = symmetricKey.CreateDecryptor(keyBytes, initialVectorBytes))
{
using (var memStream = new MemoryStream(cipherTextBytes))
{
using (var cryptoStream = new CryptoStream(memStream, decryptor, CryptoStreamMode.Read))
{
byteCount = cryptoStream.Read(plainTextBytes, 0, plainTextBytes.Length);
memStream.Close();
cryptoStream.Close();
}
}
}
symmetricKey.Clear();
return Encoding.UTF8.GetString(plainTextBytes, 0, byteCount);
}
If anyone can give me a same function for nodejs, that's will be really help. Anyway, thanks for read this post.
First, we'll do the PasswordDeriveBytes
function with Node.js. This is crypto.pbkdf2
:
// assumes HMAC-SHA1
crypto.pbkdf2(password, salt, iterations, keySize / 8, function(err, key) {
if(err) /* handle error */
// ...
});
Next, use crypto.createDecipheriv
to create a decryptor:
// find algorithm from the available ciphers; see crypto.getCiphers()
var decipher = crypto.createDecipheriv(/* algorithm */, key, initialVector);
Then use decipher.update
and decipher.final
to feed it the data. They will return portions of decrypted data to you.
Having the exact same scenario I was able to get to a successful "C# encrypt => Node decrypt" solution using the code provided by @icktoofay above, but with the PasswordDeriveBytes replaced with Rfc2898DeriveBytes
My code is roughly:
C#
private byte[] saltBytes = ASCIIEncoding.ASCII.GetBytes(salt);
public string Encrypt<T>(string value, string password) where T: SymmetricAlgorithm, new() {
byte[] valueBytes = UTF8Encoding.UTF8.GetBytes(value);
byte[] encrypted = null;
using (T cipher = new T()) {
var db = new Rfc2898DeriveBytes(password, saltBytes);
db.IterationCount = iterationsConst;
var key = db.GetBytes(keySizeConst / 8);
cipher.Mode = CipherMode.CBC;
using (ICryptoTransform encryptor = cipher.CreateEncryptor(key, vectorBytes)) {
using (MemoryStream ms = new MemoryStream()) {
using (CryptoStream cs = new CryptoStream(ms, encryptor, CryptoStreamMode.Write)) {
cs.Write(valueBytes, 0, valueBytes.Length);
cs.FlushFinalBlock();
encrypted = ms.ToArray();
}
}
}
cipher.Clear();
}
return Convert.ToBase64String(encrypted);
}
JavaScript:
var crypto = require('crypto');
var base64 = require('base64-js');
var algorithm = 'AES-256-CBC';
[...]
var saltBuffer = new Buffer(salt);
var passwordBuffer = new Buffer(password);
[...]
var encodedBuffer = new Buffer(base64.toByteArray(encryptedStringBase64Encoded));
crypto.pbkdf2(passwordBuffer, saltBuffer, iterations, keySize / 8, function(err, key) {
var decipher = crypto.createDecipheriv(algorithm, key, iv);
var dec = Buffer.concat([decipher.update(encodedBuffer), decipher.final()]);
return dec;
});
and is actually a combination of a few examples I found on the Internet.
Because I had a problem with the Buffer's implementation of Base64 in some specific cases ('+' sign at the beginning of the encoded string), I used base64-js from https://github.com/beatgammit/base64-js , which seems to work fine.
The problem is, that PasswordDeriveBytes does not implement pbkdf2 but a modified version of pbkdf1 (PKCS #5 v2.1). See this what-is-the-algorithm-behind-passwordderivebytes for more information.
Note: The defaults of the PasswordDeriveBytes constructor are iterations = 100 and hashAlgorithm = "sha1"
Here is my approach to implement this algorithm in javascript/typescript:
export function deriveBytesFromPassword(password: string, salt: Buffer, iterations: number, hashAlgorithm: string, keyLength: number) {
if (keyLength < 1) throw new Error("keyLength must be greater than 1")
if (iterations < 2) throw new Error("iterations must be greater than 2")
const passwordWithSalt = Buffer.concat([Buffer.from(password, "utf-8"), salt])
const hashMissingLastIteration = hashKeyNTimes(passwordWithSalt, iterations - 1, hashAlgorithm)
let result = hashKeyNTimes(hashMissingLastIteration, 1, hashAlgorithm)
result = extendResultIfNeeded(result, keyLength, hashMissingLastIteration, hashAlgorithm)
return result.slice(0, keyLength)
}
function hashKeyNTimes(key: Buffer, times: number, hashAlgorithm: string): Buffer {
let result = key
for (let i = 0; i < times; i++) {
result = crypto.createHash(hashAlgorithm).update(result).digest()
}
return result
}
function extendResultIfNeeded(result: Buffer, keyLength: number, hashMissingLastIteration: Buffer, hashAlgorithm: string): Buffer {
let counter = 1
while (result.length < keyLength) {
result = Buffer.concat([result, calculateSpecialMicrosoftHash(hashMissingLastIteration, counter, hashAlgorithm)])
counter++
}
return result
}
function calculateSpecialMicrosoftHash(hashMissingLastIteration: Buffer, counter: number, hashAlgorithm: string): Buffer {
// Here comes the magic: Convert an integer that increases from call to call to a string
// and convert that string to utf-8 bytes. These bytes are than used to slightly modify a given base-hash.
// The modified hash is than piped through the hash algorithm.
// Note: The PasswordDeriveBytes algorithm converts each character to utf-16 and then drops the second byte.
const prefixCalculatedByCounter = Buffer.from(counter.toString(), "utf-8")
const inputForAdditionalHashIteration = Buffer.concat([prefixCalculatedByCounter, hashMissingLastIteration])
return crypto.createHash(hashAlgorithm).update(inputForAdditionalHashIteration).digest()
}
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