AES/Rijndael-Decryption in C#, Decryption in JavaScript (Node) - c#

I'm currently facing a problem, where I have to decode encrypted files in a Node-Backend. The encryption code is available in C# and looks in it's basics like
private static byte[] DeCrypt(byte[] encdata, string pw)
{
RijndaelManaged rd = new RijndaelManaged();
int rijndaelIvLength = 16;
MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();
byte[] key = md5.ComputeHash(Encoding.UTF8.GetBytes(pw));
md5.Clear();
MemoryStream ms = new MemoryStream(encdata);
byte[] iv = new byte[16];
ms.Read(iv, 0, rijndaelIvLength);
rd.IV = iv;
rd.Key = key;
CryptoStream cs = new CryptoStream(ms, rd.CreateDecryptor(), CryptoStreamMode.Read);
byte[] data = new byte[ms.Length - rijndaelIvLength + 1];
int i = cs.Read(data, 0, data.Length);
cs.Close();
rd.Clear();
rd.Clear();
return data;
}
encdata are the bytes of the encrypted file, pw is a fixed password. My Node-function (including different attempts of encryption) looks like following:
const CryptoJS = require('crypto-js');
const fs = require('fs');
const converter = require('convert-string');
const Rijndael = require('rijndael-js');
const padder = require('pkcs7-padding');
const crypto = require('crypto');
async function decrypt(filePath, password) {
const encryptedFile = fs.readFileSync(filePath).buffer;
const chunks = [];
for await (let chunk of fs.createReadStream(filePath, { start: 0, end: 15 })) {
chunks.push(chunk);
}
const iv = Buffer.concat(chunks);
const hex = CryptoJS.MD5(password).toString();
const keyChunks = [];
for (var i = 0; i < hex.length; i += 2) {
keyChunks.push(parseInt(hex.substr(i, 2), 16));
}
const key = Buffer.from(keyChunks);
const decipher = new Rijndael(key, 'cbc');
const decryptedPadded = decipher.decrypt(encryptedFile, 128, iv);
//Remember to un-pad result
const decrypted = padder.unpad(decryptedPadded, 32);
const clearText = decrypted.toString('utf8');
const paddedText = decryptedPadded.toString('utf16le');
const plaidddnText = CryptoJS.enc.Utf16LE.stringify(decrypted);
const testttt = crypto.createCipheriv("aes128", key, iv);
const decrpyted = Buffer.concat([testttt.update(Buffer.from(encryptedFile)), testttt.final()]);
const testdec = decrypted.toString();
const bla = CryptoJS.AES.decrypt(encryptedFile, key, { keySize: 16, iv: iv, mode: CryptoJS.mode.CBC, padding: CryptoJS.pad.Pkcs7 });
const plainText = CryptoJS.enc.Utf16LE.stringify(bla);
}
When debugging both codes, I already manage that the byte arrays of the file (encdata in C#, encryptedFile in JS), and the byte arrays of iv and key are already the same, but somehow the final decryption is delivering different results. Anybody any ideas what I'm doing wrong in the final step?
Any help much appreciated! :)


As pointed out the solution is to change the unpadding to 16 bytes and decrypt from a Buffer:
const decryptedPadded = Buffer.from(decipher.decrypt(encryptedFile, 128, iv));
const decrypted = padder.unpad(decryptedPadded, 16);
const clearText = decrypted.toString('utf16le');
Now I only need to remove the first few bytes with the IV :)

Related

How to upgrade from RijndaelManaged to AES?

I have a working solution for crypt/decrypt data in my code (below) but when I have upgraded the project to DOTNET6, RijndaelManaged becomes obsolete:
Warning SYSLIB0022 'RijndaelManaged' is obsolete: 'The Rijndael and RijndaelManaged types are obsolete. Use Aes instead.'
and
SYSLIB0023 'RNGCryptoServiceProvider' is obsolete: 'RNGCryptoServiceProvider is obsolete. To generate a random number, use one of the RandomNumberGenerator static methods instead.'
Now I want to change that to Aes/RandomNumberGenerator as stated but want to keep the output in the same way as is. Unfortunately, I am not familiar with crypt/decrypt.
Can somebody help me to rewrite the current block to work with Aes instead - or at least help me how to change that and keep the public methods works in the same way?
Whole Code I have (it works as is)
using System.Security.Cryptography;
namespace MyApp;
internal static class AES
{
private static byte[] AES_Encrypt(byte[] bytesToBeEncrypted, byte[] passwordBytes)
{
byte[] encryptedBytes;
byte[] saltBytes = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8 };
using (MemoryStream ms = new())
{
using RijndaelManaged AES = new(); // This reports Warning SYSLIB0022 'RijndaelManaged' is obsolete: 'The Rijndael and RijndaelManaged types are obsolete. Use Aes instead.
AES.KeySize = 256;
AES.BlockSize = 128;
var key = new Rfc2898DeriveBytes(passwordBytes, saltBytes, 1000);
AES.Key = key.GetBytes(AES.KeySize / 8);
AES.IV = key.GetBytes(AES.BlockSize / 8);
AES.Mode = CipherMode.CBC;
using (var cs = new CryptoStream(ms, AES.CreateEncryptor(), CryptoStreamMode.Write))
{
cs.Write(bytesToBeEncrypted, 0, bytesToBeEncrypted.Length);
cs.Close();
}
encryptedBytes = ms.ToArray();
}
return encryptedBytes;
}
private static byte[] AES_Decrypt(byte[] bytesToBeDecrypted, byte[] passwordBytes)
{
byte[] decryptedBytes = null;
byte[] saltBytes = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8 };
using (MemoryStream ms = new())
{
using RijndaelManaged AES = new(); // This reports Warning SYSLIB0022 'RijndaelManaged' is obsolete: 'The Rijndael and RijndaelManaged types are obsolete. Use Aes instead.
AES.KeySize = 256;
AES.BlockSize = 128;
var key = new Rfc2898DeriveBytes(passwordBytes, saltBytes, 1000);
AES.Key = key.GetBytes(AES.KeySize / 8);
AES.IV = key.GetBytes(AES.BlockSize / 8);
AES.Mode = CipherMode.CBC;
using (var cs = new CryptoStream(ms, AES.CreateDecryptor(), CryptoStreamMode.Write))
{
cs.Write(bytesToBeDecrypted, 0, bytesToBeDecrypted.Length);
cs.Close();
}
decryptedBytes = ms.ToArray();
}
return decryptedBytes;
}
public static string EncryptText(string password, string salt = "MySecretSaltWhichIWantToKeepWorking")
{
byte[] bytesToBeEncrypted = Encoding.UTF8.GetBytes(password);
byte[] passwordBytes = Encoding.UTF8.GetBytes(salt);
passwordBytes = SHA256.Create().ComputeHash(passwordBytes);
byte[] bytesEncrypted = AES_Encrypt(bytesToBeEncrypted, passwordBytes);
string result = Convert.ToBase64String(bytesEncrypted);
return result;
}
public static string DecryptText(string hash, string salt = "MySecretSaltWhichIWantToKeepWorking")
{
try
{
byte[] bytesToBeDecrypted = Convert.FromBase64String(hash);
byte[] passwordBytes = Encoding.UTF8.GetBytes(salt);
passwordBytes = SHA256.Create().ComputeHash(passwordBytes);
byte[] bytesDecrypted = AES_Decrypt(bytesToBeDecrypted, passwordBytes);
string result = Encoding.UTF8.GetString(bytesDecrypted);
return result;
}
catch (Exception e)
{
return e.Message;
}
}
private const int SALT_BYTE_SIZE = 24;
private const int HASH_BYTE_SIZE = 24;
private const int PBKDF2_ITERATIONS = 1000;
private const int ITERATION_INDEX = 0;
private const int SALT_INDEX = 1;
private const int PBKDF2_INDEX = 2;
public static string PBKDF2_CreateHash(string password)
{
RNGCryptoServiceProvider csprng = new(); // This reports SYSLIB0023 'RNGCryptoServiceProvider' is obsolete: 'RNGCryptoServiceProvider is obsolete. To generate a random number, use one of the RandomNumberGenerator static methods instead.'
byte[] salt = new byte[SALT_BYTE_SIZE];
csprng.GetBytes(salt);
byte[] hash = PBKDF2(password, salt, PBKDF2_ITERATIONS, HASH_BYTE_SIZE);
return PBKDF2_ITERATIONS + ":" + Convert.ToBase64String(salt) + ":" + Convert.ToBase64String(hash);
}
public static bool PBKDF2_ValidatePassword(string password, string correctHash)
{
char[] delimiter = { ':' };
string[] split = correctHash.Split(delimiter);
int iterations = Int32.Parse(split[ITERATION_INDEX]);
byte[] salt = Convert.FromBase64String(split[SALT_INDEX]);
byte[] hash = Convert.FromBase64String(split[PBKDF2_INDEX]);
byte[] testHash = PBKDF2(password, salt, iterations, hash.Length);
return SlowEquals(hash, testHash);
}
private static bool SlowEquals(byte[] a, byte[] b)
{
uint diff = (uint)a.Length ^ (uint)b.Length;
for (int i = 0; i < a.Length && i < b.Length; i++)
diff |= (uint)(a[i] ^ b[i]);
return diff == 0;
}
private static byte[] PBKDF2(string password, byte[] salt, int iterations, int outputBytes)
{
Rfc2898DeriveBytes pbkdf2 = new(password, salt)
{
IterationCount = iterations
};
return pbkdf2.GetBytes(outputBytes);
}
}

As far as I can tell, you should be able to replace
using RijndaelManaged AES = new();
with
using var AES = Aes.Create("AesManaged");
note that you might want to change your variable name to avoid naming conflicts or confusion.
The only difference between AES and Rijndael should be that Rijndael allows more blocksizes/keysizes. But you seem to be using 256 bit key and 128 bit blocks, and this should be allowed by AES.

Encoding in RSA in C# for Symfony(PHP) [duplicate]

I'm trying to encrypt some (cookie) data in C# and then decrypt it in PHP. I have chosen to use Rijndael encryption. I've almost got it working, except only part of the text is decrypted! I started working from this example: Decrypt PHP encrypted string in C#
Here's the text (JSON) that I am encrypting (sensitive information removed):
{"DisplayName":"xxx", "Username": "yyy", "EmailAddress":"zzz"}
So I login to the C# app which creates/encodes the cookie from stored Key and IV and then redirects to the PHP app which is supposed to decrypt/read the cookie. When I decrypt the cookie, it comes out like this:
{"DisplayName":"xxx","F�A ;��HP=D�������4��z����ť���k�#E���R�j�5�\�t. t�D��"
UPDATE: i've gotten a little bit further and this is now the result
string(96) "{"DisplayName":"xxx","Username":"yyy","EmailAddress"�)ق��-�J��k/VV-v� �9�B`7^"
As you can see, it starts decrypting it, but then gets messed up...
When Decrypt the string it comes out correct (with padding, which I have a function to remove padding), but if I change the test string by one character I get garbage again:
B�nHL�Ek �¿?�UΣlO����OЏ�M��NO/�f.M���Lƾ�CC�Y>F��~�qd�+
Here's the c# code I use to generate the random Key and IV:
UPDATE: I'm just using static key/IV for now, here they are:
Key: lkirwf897+22#bbtrm8814z5qq=498j5
IV: 741952hheeyy66#cs!9hjv887mxx7#8y
RijndaelManaged symmetricKey = new RijndaelManaged();
symmetricKey.BlockSize = 256;
symmetricKey.KeySize = 256;
symmetricKey.Padding = PaddingMode.Zeros;
symmetricKey.Mode = CipherMode.CBC;
string key = Convert.ToBase64String(symmetricKey.Key);
string IV = Convert.ToBase64String(symmetricKey.IV);
I then save the key and IV to a database to be retrieved later for encoding/decoding.
This is the full encryption class:
public static class Encryption
{
public static string Encrypt(string prm_text_to_encrypt, string prm_key, string prm_iv)
{
var sToEncrypt = prm_text_to_encrypt;
var rj = new RijndaelManaged()
{
Padding = PaddingMode.PKCS7,
Mode = CipherMode.CBC,
KeySize = 256,
BlockSize = 256,
//FeedbackSize = 256
};
var key = Encoding.ASCII.GetBytes(prm_key);
var IV = Encoding.ASCII.GetBytes(prm_iv);
//var key = Convert.FromBase64String(prm_key);
//var IV = Convert.FromBase64String(prm_iv);
var encryptor = rj.CreateEncryptor(key, IV);
var msEncrypt = new MemoryStream();
var csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write);
var toEncrypt = Encoding.ASCII.GetBytes(sToEncrypt);
csEncrypt.Write(toEncrypt, 0, toEncrypt.Length);
csEncrypt.FlushFinalBlock();
var encrypted = msEncrypt.ToArray();
return (Convert.ToBase64String(encrypted));
}
public static string Decrypt(string prm_text_to_decrypt, string prm_key, string prm_iv)
{
var sEncryptedString = prm_text_to_decrypt;
var rj = new RijndaelManaged()
{
Padding = PaddingMode.PKCS7,
Mode = CipherMode.CBC,
KeySize = 256,
BlockSize = 256,
//FeedbackSize = 256
};
var key = Encoding.ASCII.GetBytes(prm_key);
var IV = Encoding.ASCII.GetBytes(prm_iv);
//var key = Convert.FromBase64String(prm_key);
//var IV = Convert.FromBase64String(prm_iv);
var decryptor = rj.CreateDecryptor(key, IV);
var sEncrypted = Convert.FromBase64String(sEncryptedString);
var fromEncrypt = new byte[sEncrypted.Length];
var msDecrypt = new MemoryStream(sEncrypted);
var csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read);
csDecrypt.Read(fromEncrypt, 0, fromEncrypt.Length);
return (Encoding.ASCII.GetString(fromEncrypt));
}
public static void GenerateKeyIV(out string key, out string IV)
{
var rj = new RijndaelManaged()
{
Padding = PaddingMode.PKCS7,
Mode = CipherMode.CBC,
KeySize = 256,
BlockSize = 256,
//FeedbackSize = 256
};
rj.GenerateKey();
rj.GenerateIV();
key = Convert.ToBase64String(rj.Key);
IV = Convert.ToBase64String(rj.IV);
}
}
Here's the PHP code I am using to decrypt the data:
function decryptRJ256($key,$iv,$string_to_decrypt)
{
$string_to_decrypt = base64_decode($string_to_decrypt);
$rtn = mcrypt_decrypt(MCRYPT_RIJNDAEL_256, $key, $string_to_decrypt, MCRYPT_MODE_CBC, $iv);
//$rtn = rtrim($rtn, "\0\4");
$rtn = unpad($rtn);
return($rtn);
}
function unpad($value)
{
$blockSize = mcrypt_get_block_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_CBC);
//apply pkcs7 padding removal
$packing = ord($value[strlen($value) - 1]);
if($packing && $packing < $blockSize){
for($P = strlen($value) - 1; $P >= strlen($value) - $packing; $P--){
if(ord($value{$P}) != $packing){
$packing = 0;
}//end if
}//end for
}//end if
return substr($value, 0, strlen($value) - $packing);
}
$ky = 'lkirwf897+22#bbtrm8814z5qq=498j5'; // 32 * 8 = 256 bit key
$iv = '741952hheeyy66#cs!9hjv887mxx7#8y'; // 32 * 8 = 256 bit iv
$enc = $_COOKIE["MyCookie"];
$dtext = decryptRJ256($ky, $iv, $enc);
var_dump($dtext);
I am a little unsure about this part, because all of the example code I've seen simply passes in the base64 encoded string directly to the decryptor, but in my example, I have to base64_decode it before I pass it otherwise I get the error that the key and IV are not the correct length.
UPDATE: I'm using ASCII keys in the format needed by PHP. If I generate keys from the RijndaelManaged class they dont work on the PHP side, but I can use keys that are known to work on PHP side and use them in the RijndaelManaged C# side.
Please let me know if I left out any pertinent information. TIA!

For posterity I'm placing the fully completed solution here.
C# Encryption Class
public static class Encryption
{
public static string Encrypt(string prm_text_to_encrypt, string prm_key, string prm_iv)
{
var sToEncrypt = prm_text_to_encrypt;
var rj = new RijndaelManaged()
{
Padding = PaddingMode.PKCS7,
Mode = CipherMode.CBC,
KeySize = 256,
BlockSize = 256,
};
var key = Convert.FromBase64String(prm_key);
var IV = Convert.FromBase64String(prm_iv);
var encryptor = rj.CreateEncryptor(key, IV);
var msEncrypt = new MemoryStream();
var csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write);
var toEncrypt = Encoding.ASCII.GetBytes(sToEncrypt);
csEncrypt.Write(toEncrypt, 0, toEncrypt.Length);
csEncrypt.FlushFinalBlock();
var encrypted = msEncrypt.ToArray();
return (Convert.ToBase64String(encrypted));
}
public static string Decrypt(string prm_text_to_decrypt, string prm_key, string prm_iv)
{
var sEncryptedString = prm_text_to_decrypt;
var rj = new RijndaelManaged()
{
Padding = PaddingMode.PKCS7,
Mode = CipherMode.CBC,
KeySize = 256,
BlockSize = 256,
};
var key = Convert.FromBase64String(prm_key);
var IV = Convert.FromBase64String(prm_iv);
var decryptor = rj.CreateDecryptor(key, IV);
var sEncrypted = Convert.FromBase64String(sEncryptedString);
var fromEncrypt = new byte[sEncrypted.Length];
var msDecrypt = new MemoryStream(sEncrypted);
var csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read);
csDecrypt.Read(fromEncrypt, 0, fromEncrypt.Length);
return (Encoding.ASCII.GetString(fromEncrypt));
}
public static void GenerateKeyIV(out string key, out string IV)
{
var rj = new RijndaelManaged()
{
Padding = PaddingMode.PKCS7,
Mode = CipherMode.CBC,
KeySize = 256,
BlockSize = 256,
};
rj.GenerateKey();
rj.GenerateIV();
key = Convert.ToBase64String(rj.Key);
IV = Convert.ToBase64String(rj.IV);
}
}
PHP Decryption Snippet
<?php
function decryptRJ256($key,$iv,$encrypted)
{
//PHP strips "+" and replaces with " ", but we need "+" so add it back in...
$encrypted = str_replace(' ', '+', $encrypted);
//get all the bits
$key = base64_decode($key);
$iv = base64_decode($iv);
$encrypted = base64_decode($encrypted);
$rtn = mcrypt_decrypt(MCRYPT_RIJNDAEL_256, $key, $encrypted, MCRYPT_MODE_CBC, $iv);
$rtn = unpad($rtn);
return($rtn);
}
//removes PKCS7 padding
function unpad($value)
{
$blockSize = mcrypt_get_block_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_CBC);
$packing = ord($value[strlen($value) - 1]);
if($packing && $packing < $blockSize)
{
for($P = strlen($value) - 1; $P >= strlen($value) - $packing; $P--)
{
if(ord($value{$P}) != $packing)
{
$packing = 0;
}
}
}
return substr($value, 0, strlen($value) - $packing);
}
?>
<pre>
<?php
$enc = $_COOKIE["MyCookie"];
$ky = ""; //INSERT THE KEY GENERATED BY THE C# CLASS HERE
$iv = ""; //INSERT THE IV GENERATED BY THE C# CLASS HERE
$json_user = json_decode(decryptRJ256($ky, $iv, $enc), true);
var_dump($json_user);
?>

Since the string is partially OK, but there is gibberish at the end it would suggest a padding problem within the encryption which expects exact blocks of 256 bytes. I suggest setting the padding as PKCS7 (PaddingMode.PKCS7) instead of Zeros on the C# side which PHP will understand without issues (as it's the default mode on that parser).
Edit: Oops, I did not notice that you had the following in your PHP:
$enc = $_COOKIE["MyCookie"];
This is the caveat. PHP is likely not getting the encrypted data as-is and is running some urldecode sanitizing. You should print this variable to see that it really matches what is being sent from the C# code.
Edit2:
Convert the whitespaces to missing + characters from the cookie by adding this:
str_replace(' ', '+', $enc);

Decrypt a base64 string using C# generated by iOs CCCrypt function using AES

Could someone please help decrypt the base64 string generated by iOS code below into its C# equivalent.
I am trying to end up with "Meet me at the secret location at 8pm" within c#.
iOS generated the following encryption: qd+SGaij5KSBScuLs3TpJS/3Dew8fHTudcs/5MG7Q1kqcrZzZycMgTcQuEEEED5f
This iOS code successfully encrypts and decrypts data as required within XCode 6.
Thank you in advance for your help and support.
Darren
#import <CommonCrypto/CommonCryptor.h>
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
NSString *sData = #"Meet me at the secret location at 8pm";
NSString *sIv = #"4QesEr03HwE5H1C+ICw7SA==";
NSString *sKey = #"ovA6siPkyM5Lb9oNcnxLz676K6JK6FrJKk4efEUWBzg=";
NSData *dData = [sData dataUsingEncoding:NSUTF8StringEncoding];
NSData *dIv = [sIv dataUsingEncoding:NSUTF8StringEncoding];
NSData *dKey = [sKey dataUsingEncoding:NSUTF8StringEncoding];
NSData *dEncrypt = [self doCipher:dData iv:dIv key:dKey context:kCCEncrypt];
NSData *dDecrypt = [self doCipher:dEncrypt iv:dIv key:dKey context:kCCDecrypt];
NSString *sDecrypt = [[NSString alloc] initWithData:dDecrypt encoding:NSUTF8StringEncoding];
NSLog(#"Decrypted Data: %#",sDecrypt);
}
- (NSData *)doCipher:(NSData *)dataIn
iv:(NSData *)iv
key:(NSData *)symmetricKey
context:(CCOperation)encryptOrDecrypt
{
CCCryptorStatus ccStatus = kCCSuccess;
size_t cryptBytes = 0; // Number of bytes moved to buffer.
NSMutableData *dataOut = [NSMutableData dataWithLength:dataIn.length + kCCBlockSizeAES128];
ccStatus = CCCrypt( encryptOrDecrypt,
kCCAlgorithmAES128,
kCCOptionPKCS7Padding,
symmetricKey.bytes,
kCCKeySizeAES128,
iv.bytes,
dataIn.bytes,
dataIn.length,
dataOut.mutableBytes,
dataOut.length,
&cryptBytes);
if (ccStatus != kCCSuccess) {
NSLog(#"CCCrypt status: %d", ccStatus);
}
dataOut.length = cryptBytes;
NSString *base64 = [dataOut base64EncodedStringWithOptions:0];
NSLog(#"%#",base64);
return dataOut;
}

The encrypted text on each platform now reads:
X/aopyVDDva/wJ3If/5i73JGjwth9eH45Opxaaswgb8Kx3ynh8BhBTFRrHT0/i3y
Here is the working C# code
NOTE: C# code extracted from https://github.com/Pakhee/Cross-platform-AES-encryption
namespace CryptoTest
{
public partial class Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
string iv = "4QesEr03HwE5H1C+ICw7SA=="; // origional iv 128 bits
string key = "ovA6siPkyM5Lb9oNcnxLz676K6JK6FrJKk4efEUWBzg="; // origional key 256 bits
string message = "Meet me at the secret location at 8pm";
CryptLib cryptLib = new CryptLib();
string encryptedText = cryptLib.encrypt(message, key, iv);
string originalMessage = cryptLib.decrypt(encryptedText, key, iv);
Debug.WriteLine(originalMessage);
}
}
public class CryptLib
{
UTF8Encoding _enc;
RijndaelManaged _rcipher;
byte[] _key, _pwd, _ivBytes, _iv;
private enum EncryptMode { ENCRYPT, DECRYPT };
public CryptLib()
{
_enc = new UTF8Encoding();
_rcipher = new RijndaelManaged();
_rcipher.Mode = CipherMode.CBC;
_rcipher.Padding = PaddingMode.PKCS7;
_rcipher.KeySize = 256;
_rcipher.BlockSize = 128;
_key = new byte[32];
_iv = new byte[_rcipher.BlockSize / 8]; //128 bit / 8 = 16 bytes
_ivBytes = new byte[16];
}
private String encryptDecrypt(string _inputText, string _encryptionKey, EncryptMode _mode, string _initVector)
{
string _out = "";// output string
_pwd = Encoding.UTF8.GetBytes(_encryptionKey);
_ivBytes = Encoding.UTF8.GetBytes(_initVector);
int len = _pwd.Length;
if (len > _key.Length)
{
len = _key.Length;
}
int ivLenth = _ivBytes.Length;
if (ivLenth > _iv.Length)
{
ivLenth = _iv.Length;
}
Array.Copy(_pwd, _key, len);
Array.Copy(_ivBytes, _iv, ivLenth);
_rcipher.Key = _key;
_rcipher.IV = _iv;
if (_mode.Equals(EncryptMode.ENCRYPT))
{
//encrypt
byte[] plainText = _rcipher.CreateEncryptor().TransformFinalBlock(_enc.GetBytes(_inputText), 0, _inputText.Length);
_out = Convert.ToBase64String(plainText);
}
if (_mode.Equals(EncryptMode.DECRYPT))
{
//decrypt
byte[] plainText = _rcipher.CreateDecryptor().TransformFinalBlock(Convert.FromBase64String(_inputText), 0, Convert.FromBase64String(_inputText).Length);
_out = _enc.GetString(plainText);
}
_rcipher.Dispose();
return _out;// return encrypted/decrypted string
}
public string encrypt(string _plainText, string _key, string _initVector)
{
return encryptDecrypt(_plainText, _key, EncryptMode.ENCRYPT, _initVector);
}
public string decrypt(string _encryptedText, string _key, string _initVector)
{
return encryptDecrypt(_encryptedText, _key, EncryptMode.DECRYPT, _initVector);
}
}
}
Here is the working iOS code
#import <CommonCrypto/CommonCryptor.h>
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
NSString *sData = #"Meet me at the secret location at 8pm";
NSString *sIv = #"4QesEr03HwE5H1C+ICw7SA==";
NSString *sKey = #"ovA6siPkyM5Lb9oNcnxLz676K6JK6FrJKk4efEUWBzg=";
NSData *dData = [sData dataUsingEncoding:NSUTF8StringEncoding];
NSData *dEncrypt = [self doCipher:dData key:sKey iv:sIv context:kCCEncrypt];
NSData *base64 = [dEncrypt base64EncodedDataWithOptions:0];
NSString *sBase64 = [[NSString alloc] initWithData:base64 encoding:NSUTF8StringEncoding];
NSLog(#"Base64 String: %#",sBase64);
NSData *dDecrypt= [self decrypt:dEncrypt key:sKey iv:sIv];
NSString *sDecrypt = [[NSString alloc] initWithData:dDecrypt encoding:NSUTF8StringEncoding];
NSLog(#"Decrypted Data: %#",sDecrypt);
}
- (NSData *)doCipher:(NSData *)plainText
key:(NSString *)key
iv:(NSString *)iv
context:(CCOperation)encryptOrDecrypt
{
NSUInteger dataLength = [plainText length];
size_t buffSize = dataLength + kCCBlockSizeAES128;
void *buff = malloc(buffSize);
size_t numBytesEncrypted = 0;
NSData *dIv = [iv dataUsingEncoding:NSUTF8StringEncoding];
NSData *dKey = [key dataUsingEncoding:NSUTF8StringEncoding];
CCCryptorStatus status = CCCrypt(encryptOrDecrypt,
kCCAlgorithmAES128,
kCCOptionPKCS7Padding,
dKey.bytes, kCCKeySizeAES256,
dIv.bytes,
[plainText bytes], [plainText length],
buff, buffSize,
&numBytesEncrypted);
if (status == kCCSuccess) {
return [NSData dataWithBytesNoCopy:buff length:numBytesEncrypted];
}
free(buff);
return nil;
}

The given base64 string qd+SGaij5KSBScuLs3TpJS/3Dew8fHTudcs/5MG7Q1kqcrZzZycMgTcQuEEEED5f is a two way pack.
First it has to be base64 decoded (which is easy in C#) and afterwards it has to be decrypted by using the correct algorithm. From the given parameters it hopefully uses the AES or Rijndael algorithm (example code here) where you have to put in the base64 decoded bytes, the key and the IV.
After that you hopefully get out your desired data.
So i wrote an example on myself and i'm able to encrypt and decrypt the specified message with C#.
But the retrieved encrypted message differs from the iOS generated message:
Your iOS message: qd+SGaij5KSBScuLs3TpJS/3Dew8fHTudcs/5MG7Q1kqcrZzZycMgTcQuEEEED5f
My C# message: wC2dn+QVhOhf+NqZVskopLdh2XDAdG3SmczrKF+TjQsGfxu07BEhRdiDqkbGY80O
I just made some little changes and dit a little deeper look. One thing i see is that you say in your iOS code that the key has a length of 256 bit. But the key you are providing has only a length of 128 bit. It seems that C# in that case simply switches back to 128 bit key length (cause changing the key size in the code below doesn't change the encrypted bytes). But maybe the CCCrypt in iOS makes something different. So either adopt in your iOS code the key size or provider a 256 bit key and than compare the results of iOS and C# again.
Example:
var message = #"Meet me at the secret location at 8pm";
var iv = #"4QesEr03HwE5H1C+ICw7SA==";
var key = #"ovA6siPkyM5Lb9oNcnxLz676K6JK6FrJKk4efEUWBzg=";
byte[] encryptedBytes;
using (var aesCryptoProvider = new AesCryptoServiceProvider())
{
aesCryptoProvider.BlockSize = 128;
aesCryptoProvider.KeySize = 256;
aesCryptoProvider.IV = Convert.FromBase64String(iv);
aesCryptoProvider.Key = Convert.FromBase64String(key);
aesCryptoProvider.Padding = PaddingMode.PKCS7;
aesCryptoProvider.Mode = CipherMode.CBC;
using (var encryptor = aesCryptoProvider.CreateEncryptor())
using (var memoryStream = new MemoryStream())
using (var cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write))
using (var streamWriter = new StreamWriter(cryptoStream, Encoding.UTF8))
{
streamWriter.Write(message);
streamWriter.Close();
encryptedBytes = memoryStream.ToArray();
}
}
var encryptedMessage = Convert.ToBase64String(encryptedBytes);
Console.WriteLine(encryptedMessage);
using (var aesCryptoProvider = new AesCryptoServiceProvider())
{
aesCryptoProvider.BlockSize = 128;
aesCryptoProvider.KeySize = 256;
aesCryptoProvider.IV = Convert.FromBase64String(iv);
aesCryptoProvider.Key = Convert.FromBase64String(key);
aesCryptoProvider.Padding = PaddingMode.PKCS7;
aesCryptoProvider.Mode = CipherMode.CBC;
using (var decryptor = aesCryptoProvider.CreateDecryptor())
using (var memoryStream = new MemoryStream(Convert.FromBase64String(encryptedMessage)))
using (var cryptoStream = new CryptoStream(memoryStream, decryptor, CryptoStreamMode.Read))
using (var streamReader = new StreamReader(cryptoStream, Encoding.UTF8))
{
Console.WriteLine(streamReader.ReadToEnd());
}
}

AES cbc padding encryption/decryption on cross platform (.net c# and codename one bouncy castle)

Encryption/Decryption won't work in cross platform.
I have used this link to encrypt/decrypt text using bouncy castle AES cipher within codename one.
AES Encryption/Decryption with Bouncycastle Example in J2ME
While from server side (.net) , i am using this link to implement same method.
http://zenu.wordpress.com/2011/09/21/aes-128bit-cross-platform-java-and-c-encryption-compatibility/
now i am not getting any error but encrypted from codename one will not getting fully decrypted on server side and vice a versa.
any one please help me out on this.
Code from Codename one:
import org.bouncycastle.crypto.CipherParameters;
import org.bouncycastle.crypto.CryptoException;
import org.bouncycastle.crypto.engines.AESEngine;
import org.bouncycastle.crypto.modes.CBCBlockCipher;
import org.bouncycastle.crypto.paddings.PaddedBufferedBlockCipher;
import org.bouncycastle.crypto.params.KeyParameter;
import org.bouncycastle.crypto.params.ParametersWithIV;
import org.bouncycastle.util.encoders.Base64;
public class Test
{
private static PaddedBufferedBlockCipher cipher = null;
public static void main(String[] args)
{
try
{
byte key[] = "MAKV2SPBNI992122".getBytes("UTF-8");
byte[] iv = new byte[16];
PaddedBufferedBlockCipher cipher = new PaddedBufferedBlockCipher(
new CBCBlockCipher(
new AESEngine()) );
//Encryption
String plainText = "Hello How are you !2#&*()% 123456#";
byte[] plainData = plainText.getBytes("UTF-8");
KeyParameter keyParam = new KeyParameter(key);
CipherParameters ivAndKey = new ParametersWithIV(keyParam, iv);
cipher.init(true, ivAndKey);
byte[] ciptherBytes = cipherData(plainData); //48
String cipherText = new String(Base64.encode(ciptherBytes), "UTF-8");//FileUtil.getStringFromByteArray(Base64.encode(ciptherBytes));
System.out.println("encrypted >> "+cipherText);
//Decryption
byte[] cipherData = Base64.decode(cipherText);
ivAndKey = new ParametersWithIV(keyParam, iv);
cipher.init(false, ivAndKey);
plainText = new String(cipherData(cipherData), "UTF-8");//FileUtil.getStringFromByteArray(cipherData(cipherData));
System.out.println("decrypted >> "+plainText);
}
catch (Exception e)
{
e.printStackTrace();
}
}
private static byte[] cipherData(byte[] data)
throws CryptoException
{
int minSize = cipher.getOutputSize(data.length);
byte[] outBuf = new byte[minSize];
int length1 = cipher.processBytes(data, 0, data.length, outBuf, 0);
int length2 = cipher.doFinal(outBuf, length1);
int actualLength = length1 + length2;
byte[] result = new byte[actualLength];
System.arraycopy(outBuf, 0, result, 0, result.length);
return result;
}
Code from .net:
public static RijndaelManaged GetRijndaelManaged(String secretKey)
{
var keyBytes = new byte[16];
var secretKeyBytes = Encoding.UTF8.GetBytes(secretKey);
Array.Copy(secretKeyBytes, keyBytes, Math.Min(keyBytes.Length, secretKeyBytes.Length));
return new RijndaelManaged
{
Mode = CipherMode.CBC,
Padding = PaddingMode.PKCS7,
KeySize = 128,
BlockSize = 128,
Key = keyBytes,
IV = keyBytes
};
}
public static byte[] EncryptCBC(byte[] plainBytes, RijndaelManaged rijndaelManaged)
{
return rijndaelManaged.CreateEncryptor()
.TransformFinalBlock(plainBytes, 0, plainBytes.Length);
}
public static byte[] DecryptCBC(byte[] encryptedData, RijndaelManaged rijndaelManaged)
{
return rijndaelManaged.CreateDecryptor()
.TransformFinalBlock(encryptedData, 0, encryptedData.Length);
}
public static String EncryptCBCStr(String plainText, String key)
{
var plainBytes = Encoding.UTF8.GetBytes(plainText);
return Convert.ToBase64String(EncryptCBC(plainBytes, GetRijndaelManaged(key)));
}
public static String DecryptCBCStr(String encryptedText, String key)
{
var encryptedBytes = Convert.FromBase64String(encryptedText);
return Encoding.UTF8.GetString(DecryptCBC(encryptedBytes, GetRijndaelManaged(key)));
}
// call
var PlainText = "Hello How are you !2#&*()% 123456#";
var EncryptionKey = "MAKV2SPBNI992122";
var cypherCBC = EncryptCBCStr(PlainText, EncryptionKey);
var decryptCBC = DecryptCBCStr(cypherCBC, EncryptionKey);
Thanks in adv.

This issue has been fixed...it is just key/IV bytes issue.as in .net there is same key and IV when in java i have used different IV.
correction in java code:
instead of this
byte key[] = "MAKV2SPBNI992122".getBytes("UTF-8");
byte[] iv = new byte[16];
use this.
byte key[] = "MAKV2SPBNI992122".getBytes("UTF-8");
byte[] iv = "MAKV2SPBNI992122".getBytes("UTF-8");

C# Encryption to PHP Decryption

I'm trying to encrypt some (cookie) data in C# and then decrypt it in PHP. I have chosen to use Rijndael encryption. I've almost got it working, except only part of the text is decrypted! I started working from this example: Decrypt PHP encrypted string in C#
Here's the text (JSON) that I am encrypting (sensitive information removed):
{"DisplayName":"xxx", "Username": "yyy", "EmailAddress":"zzz"}
So I login to the C# app which creates/encodes the cookie from stored Key and IV and then redirects to the PHP app which is supposed to decrypt/read the cookie. When I decrypt the cookie, it comes out like this:
{"DisplayName":"xxx","F�A ;��HP=D�������4��z����ť���k�#E���R�j�5�\�t. t�D��"
UPDATE: i've gotten a little bit further and this is now the result
string(96) "{"DisplayName":"xxx","Username":"yyy","EmailAddress"�)ق��-�J��k/VV-v� �9�B`7^"
As you can see, it starts decrypting it, but then gets messed up...
When Decrypt the string it comes out correct (with padding, which I have a function to remove padding), but if I change the test string by one character I get garbage again:
B�nHL�Ek �¿?�UΣlO����OЏ�M��NO/�f.M���Lƾ�CC�Y>F��~�qd�+
Here's the c# code I use to generate the random Key and IV:
UPDATE: I'm just using static key/IV for now, here they are:
Key: lkirwf897+22#bbtrm8814z5qq=498j5
IV: 741952hheeyy66#cs!9hjv887mxx7#8y
RijndaelManaged symmetricKey = new RijndaelManaged();
symmetricKey.BlockSize = 256;
symmetricKey.KeySize = 256;
symmetricKey.Padding = PaddingMode.Zeros;
symmetricKey.Mode = CipherMode.CBC;
string key = Convert.ToBase64String(symmetricKey.Key);
string IV = Convert.ToBase64String(symmetricKey.IV);
I then save the key and IV to a database to be retrieved later for encoding/decoding.
This is the full encryption class:
public static class Encryption
{
public static string Encrypt(string prm_text_to_encrypt, string prm_key, string prm_iv)
{
var sToEncrypt = prm_text_to_encrypt;
var rj = new RijndaelManaged()
{
Padding = PaddingMode.PKCS7,
Mode = CipherMode.CBC,
KeySize = 256,
BlockSize = 256,
//FeedbackSize = 256
};
var key = Encoding.ASCII.GetBytes(prm_key);
var IV = Encoding.ASCII.GetBytes(prm_iv);
//var key = Convert.FromBase64String(prm_key);
//var IV = Convert.FromBase64String(prm_iv);
var encryptor = rj.CreateEncryptor(key, IV);
var msEncrypt = new MemoryStream();
var csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write);
var toEncrypt = Encoding.ASCII.GetBytes(sToEncrypt);
csEncrypt.Write(toEncrypt, 0, toEncrypt.Length);
csEncrypt.FlushFinalBlock();
var encrypted = msEncrypt.ToArray();
return (Convert.ToBase64String(encrypted));
}
public static string Decrypt(string prm_text_to_decrypt, string prm_key, string prm_iv)
{
var sEncryptedString = prm_text_to_decrypt;
var rj = new RijndaelManaged()
{
Padding = PaddingMode.PKCS7,
Mode = CipherMode.CBC,
KeySize = 256,
BlockSize = 256,
//FeedbackSize = 256
};
var key = Encoding.ASCII.GetBytes(prm_key);
var IV = Encoding.ASCII.GetBytes(prm_iv);
//var key = Convert.FromBase64String(prm_key);
//var IV = Convert.FromBase64String(prm_iv);
var decryptor = rj.CreateDecryptor(key, IV);
var sEncrypted = Convert.FromBase64String(sEncryptedString);
var fromEncrypt = new byte[sEncrypted.Length];
var msDecrypt = new MemoryStream(sEncrypted);
var csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read);
csDecrypt.Read(fromEncrypt, 0, fromEncrypt.Length);
return (Encoding.ASCII.GetString(fromEncrypt));
}
public static void GenerateKeyIV(out string key, out string IV)
{
var rj = new RijndaelManaged()
{
Padding = PaddingMode.PKCS7,
Mode = CipherMode.CBC,
KeySize = 256,
BlockSize = 256,
//FeedbackSize = 256
};
rj.GenerateKey();
rj.GenerateIV();
key = Convert.ToBase64String(rj.Key);
IV = Convert.ToBase64String(rj.IV);
}
}
Here's the PHP code I am using to decrypt the data:
function decryptRJ256($key,$iv,$string_to_decrypt)
{
$string_to_decrypt = base64_decode($string_to_decrypt);
$rtn = mcrypt_decrypt(MCRYPT_RIJNDAEL_256, $key, $string_to_decrypt, MCRYPT_MODE_CBC, $iv);
//$rtn = rtrim($rtn, "\0\4");
$rtn = unpad($rtn);
return($rtn);
}
function unpad($value)
{
$blockSize = mcrypt_get_block_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_CBC);
//apply pkcs7 padding removal
$packing = ord($value[strlen($value) - 1]);
if($packing && $packing < $blockSize){
for($P = strlen($value) - 1; $P >= strlen($value) - $packing; $P--){
if(ord($value{$P}) != $packing){
$packing = 0;
}//end if
}//end for
}//end if
return substr($value, 0, strlen($value) - $packing);
}
$ky = 'lkirwf897+22#bbtrm8814z5qq=498j5'; // 32 * 8 = 256 bit key
$iv = '741952hheeyy66#cs!9hjv887mxx7#8y'; // 32 * 8 = 256 bit iv
$enc = $_COOKIE["MyCookie"];
$dtext = decryptRJ256($ky, $iv, $enc);
var_dump($dtext);
I am a little unsure about this part, because all of the example code I've seen simply passes in the base64 encoded string directly to the decryptor, but in my example, I have to base64_decode it before I pass it otherwise I get the error that the key and IV are not the correct length.
UPDATE: I'm using ASCII keys in the format needed by PHP. If I generate keys from the RijndaelManaged class they dont work on the PHP side, but I can use keys that are known to work on PHP side and use them in the RijndaelManaged C# side.
Please let me know if I left out any pertinent information. TIA!

For posterity I'm placing the fully completed solution here.
C# Encryption Class
public static class Encryption
{
public static string Encrypt(string prm_text_to_encrypt, string prm_key, string prm_iv)
{
var sToEncrypt = prm_text_to_encrypt;
var rj = new RijndaelManaged()
{
Padding = PaddingMode.PKCS7,
Mode = CipherMode.CBC,
KeySize = 256,
BlockSize = 256,
};
var key = Convert.FromBase64String(prm_key);
var IV = Convert.FromBase64String(prm_iv);
var encryptor = rj.CreateEncryptor(key, IV);
var msEncrypt = new MemoryStream();
var csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write);
var toEncrypt = Encoding.ASCII.GetBytes(sToEncrypt);
csEncrypt.Write(toEncrypt, 0, toEncrypt.Length);
csEncrypt.FlushFinalBlock();
var encrypted = msEncrypt.ToArray();
return (Convert.ToBase64String(encrypted));
}
public static string Decrypt(string prm_text_to_decrypt, string prm_key, string prm_iv)
{
var sEncryptedString = prm_text_to_decrypt;
var rj = new RijndaelManaged()
{
Padding = PaddingMode.PKCS7,
Mode = CipherMode.CBC,
KeySize = 256,
BlockSize = 256,
};
var key = Convert.FromBase64String(prm_key);
var IV = Convert.FromBase64String(prm_iv);
var decryptor = rj.CreateDecryptor(key, IV);
var sEncrypted = Convert.FromBase64String(sEncryptedString);
var fromEncrypt = new byte[sEncrypted.Length];
var msDecrypt = new MemoryStream(sEncrypted);
var csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read);
csDecrypt.Read(fromEncrypt, 0, fromEncrypt.Length);
return (Encoding.ASCII.GetString(fromEncrypt));
}
public static void GenerateKeyIV(out string key, out string IV)
{
var rj = new RijndaelManaged()
{
Padding = PaddingMode.PKCS7,
Mode = CipherMode.CBC,
KeySize = 256,
BlockSize = 256,
};
rj.GenerateKey();
rj.GenerateIV();
key = Convert.ToBase64String(rj.Key);
IV = Convert.ToBase64String(rj.IV);
}
}
PHP Decryption Snippet
<?php
function decryptRJ256($key,$iv,$encrypted)
{
//PHP strips "+" and replaces with " ", but we need "+" so add it back in...
$encrypted = str_replace(' ', '+', $encrypted);
//get all the bits
$key = base64_decode($key);
$iv = base64_decode($iv);
$encrypted = base64_decode($encrypted);
$rtn = mcrypt_decrypt(MCRYPT_RIJNDAEL_256, $key, $encrypted, MCRYPT_MODE_CBC, $iv);
$rtn = unpad($rtn);
return($rtn);
}
//removes PKCS7 padding
function unpad($value)
{
$blockSize = mcrypt_get_block_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_CBC);
$packing = ord($value[strlen($value) - 1]);
if($packing && $packing < $blockSize)
{
for($P = strlen($value) - 1; $P >= strlen($value) - $packing; $P--)
{
if(ord($value{$P}) != $packing)
{
$packing = 0;
}
}
}
return substr($value, 0, strlen($value) - $packing);
}
?>
<pre>
<?php
$enc = $_COOKIE["MyCookie"];
$ky = ""; //INSERT THE KEY GENERATED BY THE C# CLASS HERE
$iv = ""; //INSERT THE IV GENERATED BY THE C# CLASS HERE
$json_user = json_decode(decryptRJ256($ky, $iv, $enc), true);
var_dump($json_user);
?>

Since the string is partially OK, but there is gibberish at the end it would suggest a padding problem within the encryption which expects exact blocks of 256 bytes. I suggest setting the padding as PKCS7 (PaddingMode.PKCS7) instead of Zeros on the C# side which PHP will understand without issues (as it's the default mode on that parser).
Edit: Oops, I did not notice that you had the following in your PHP:
$enc = $_COOKIE["MyCookie"];
This is the caveat. PHP is likely not getting the encrypted data as-is and is running some urldecode sanitizing. You should print this variable to see that it really matches what is being sent from the C# code.
Edit2:
Convert the whitespaces to missing + characters from the cookie by adding this:
str_replace(' ', '+', $enc);

Categories

Resources