Equivalent PHP code for AES encryption from C#

Question

can any one please provide the equivalent PHP Code for the below C# Aes encryption, i have tried different php AES encryption but to no use, the out put not matching, thanks in advance.

the key and iv values used here are in hex and expected output is in Hex.

C#:

public class AESAlgorithm
    {

    public static string GeneratePrivateKey()
    {
        string str;

        RijndaelManaged rijndaelManaged = null;
        try
        {
            rijndaelManaged = new RijndaelManaged();
            rijndaelManaged.KeySize = 128;
            rijndaelManaged.GenerateKey();
            str = ConvertByteArrayToHexString(rijndaelManaged.Key);
        }
        finally
        {
            if (rijndaelManaged == null)
            {
                rijndaelManaged.Clear();
            }
        }
        return str;
    }

    public static string GenerateAuthKey(string timestamp, string appCode, string attUid, string privateKey)
    {
        return Encrypt(String.Format("{0}|{1}|{2}", timestamp, appCode, attUid), privateKey);
    }

    public static string Encrypt(string textToEncrypt, string hexStringKey)
    {
        string str1;

        RijndaelManaged rijndaelManaged = null;
        try
        {
            rijndaelManaged = new RijndaelManaged();
            rijndaelManaged.Mode = CipherMode.CBC;
            rijndaelManaged.Padding = PaddingMode.PKCS7;
            rijndaelManaged.KeySize = 128;
            rijndaelManaged.BlockSize = 128;
            byte[] bs1 = ConvertHexStringToByteArray(hexStringKey);
            rijndaelManaged.Key = bs1;
            rijndaelManaged.IV = bs1;
            ICryptoTransform iCryptoTransform = rijndaelManaged.CreateEncryptor();
            byte[] bs2 = Encoding.UTF8.GetBytes(textToEncrypt);
            str1 = ConvertByteArrayToHexString(iCryptoTransform.TransformFinalBlock(bs2, 0, (int)bs2.Length));
        }
        finally
        {
            if (rijndaelManaged == null)
            {
                rijndaelManaged.Clear();
            }
        }
        return str1;
    }

    public static string Decrypt(string hexStringToDecrypt, string hexStringKey)
    {
        string str1;

        RijndaelManaged rijndaelManaged = null;
        try
        {
            rijndaelManaged = new RijndaelManaged();
            rijndaelManaged.Mode = CipherMode.CBC;
            rijndaelManaged.Padding = PaddingMode.PKCS7;
            rijndaelManaged.KeySize = 128;
            rijndaelManaged.BlockSize = 128;
            byte[] bs1 = ConvertHexStringToByteArray(hexStringToDecrypt);
            byte[] bs2 = ConvertHexStringToByteArray(hexStringKey);
            rijndaelManaged.Key = bs2;
            rijndaelManaged.IV = bs2;
            byte[] bs3 = rijndaelManaged.CreateDecryptor().TransformFinalBlock(bs1, 0, (int)bs1.Length);
            str1 = Encoding.UTF8.GetString(bs3);
        }
        finally
        {
            if (rijndaelManaged == null)
            {
                rijndaelManaged.Clear();
            }
        }
        return str1;
    }

    private static string ConvertByteArrayToHexString(byte[] input)
    {
        bool flag;

        StringBuilder stringBuilder = new StringBuilder();
        byte[] bs = input;
        int i = 0;
        do
        {
            byte b = bs[i];
            stringBuilder.AppendFormat("{0:x2}", b);
            i++;

            flag = i < (int)bs.Length;
        }
        while (flag);
        return stringBuilder.ToString();
    }

    private static byte[] ConvertHexStringToByteArray(string hexString)
    {
        bool flag = (hexString.Length & 1) == 0;
        if (!flag)
        {
            throw new ArgumentOutOfRangeException("hexString", hexString, "hexString must contain an even number of characters.");
        }
        byte[] bs1 = new byte[hexString.Length / 2];
        int i = 0;
        do
        {
            bs1[i / 2] = Byte.Parse(hexString.Substring(i, 2), NumberStyles.HexNumber);
            i += 2;

            flag = i < hexString.Length;
        }
        while (flag);
        return bs1;
    }
}

Answer 1

Your sample code is really bad, you are using the key bytes as the IV, an adversary could definitely use a chosen ciphertext attack figure out the key bytes, easily. That would suck for your auth key.

IV's NEED to be unique and unpredictable for AES-CBC.

My suggestion to you since this appears to be credentials of some sort you should use Authenticated Encryption.

I have some cut and paste code I try to keep reviewed, Modern Examples of Symmetric Authenticated Encryption of a string C#

The .NET Built-in Encrypt(AES)-Then-MAC(HMAC) version of my examples should be compatible with RNCryptor when encrypting using nonSecretPayload = new byte[]{2,X}; (X being 0 without password, 1 with pasword) and decrypting with nonSecretPayloadLength = 2.

Even though RNCryptor is objective-c, I believe RNCryptor has PHP examples.