The next generation of the Teknik Services. Written in ASP.NET. https://www.teknik.io/
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using System;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
namespace Teknik.Utilities.Cryptography
{
public static class Aes128CFB
{
public static byte[] Encrypt(byte[] text, byte[] key)
{
int blockSize = 128;
int keySize = 128;
// Encode the text
string textEnc = Convert.ToBase64String(text);
byte[] textBytes = Encoding.UTF8.GetBytes(textEnc);
// cipherArray
int cipherLen = (blockSize / 8) + textEnc.Length;
byte[] cipherText = new byte[cipherLen];
Array.Clear(cipherText, 0, cipherLen);
// Create the IV needed for this operation
string ivStr = StringHelper.RandomString(blockSize / 8);
byte[] ivBytes = Encoding.UTF8.GetBytes(ivStr);
// copy IV to the cipher text start
ivBytes.CopyTo(cipherText, 0);
// Process the cipher
ProcessCipher(true, textBytes, key, ivBytes, blockSize, keySize, ref cipherText, blockSize / 8);
return cipherText;
}
public static byte[] Decrypt(byte[] text, byte[] key)
{
int blockSize = 128;
int keySize = 128;
// Grab the IV and encrypted text from the original text
byte[] ivBytes = new byte[blockSize / 8];
byte[] encText = new byte[text.Length - (blockSize / 8)];
byte[] output = new byte[text.Length - (blockSize / 8)];
text.Take(blockSize / 8).ToArray().CopyTo(ivBytes, 0);
text.Skip(blockSize / 8).ToArray().CopyTo(encText, 0);
// Pad the text for decryption
ByteHelper.PadToMultipleOf(ref encText, 16);
// Process the cipher
ProcessCipher(false, encText, key, ivBytes, blockSize, keySize, ref output, 0);
string encodedText = Encoding.UTF8.GetString(output);
return Convert.FromBase64String(encodedText);
}
public static void ProcessCipher(bool encrypt, byte[] text, byte[] key, byte[] iv, int blockSize, int keySize, ref byte[] output, int offset)
{
using (var cipher = new RijndaelManaged())
{
cipher.BlockSize = blockSize;
cipher.KeySize = keySize;
cipher.Mode = CipherMode.CFB;
cipher.FeedbackSize = 128;
cipher.Padding = PaddingMode.Zeros;
cipher.Key = key;
cipher.IV = iv;
using (var encryptor = (encrypt) ? cipher.CreateEncryptor() : cipher.CreateDecryptor())
using (MemoryStream ms = new MemoryStream())
using (CryptoStream cs = new CryptoStream(ms, encryptor, CryptoStreamMode.Write))
using (var bw = new BinaryWriter(cs, Encoding.UTF8))
{
bw.Write(text);
bw.Close();
byte[] textBytes = ms.ToArray();
for (int i = 0; i < output.Length - offset; i++)
{
output[i + offset] = textBytes[i];
}
}
}
}
}
}