Question

我正在尝试在c＃中实现AES 128 CTR加密。我发现Bouncy Castle非常有用。这是我的代码：

public class AESCrypto
{
   private byte[] Key = new byte[16];
   private byte[] IV = new byte[16];
   private const int CHUNK_SIZE = 16;
   private IBufferedCipher cipher = CipherUtilities.GetCipher("AES/CTR/NoPadding");

   // Key and IV I get from client.
   public AESCrypto(byte[] key, byte[] iv, bool forEncryption) {
      Key = key;
      IV = iv;
      cipher.Init(forEncryption, new ParametersWithIV(new KeyParameter(Key), IV));
   }

   public byte[] PerformAES(byte[] incomingBytes)
   {
            int blockCount = incomingBytes.Length / CHUNK_SIZE; // Number of blocks
            int blockRemaining = incomingBytes.Length % CHUNK_SIZE; // Remaining bytes of the last block

            byte[] outcomingBytes = new byte[incomingBytes.Length];

            for (var i = 0; i < blockCount; i++)
            {
                // Why do I need to re-init it again?
                //cipher.Init(false, new ParametersWithIV(new KeyParameter(Key), IV));

                byte[] temp = new byte[CHUNK_SIZE];
                Array.Copy(incomingBytes, i * CHUNK_SIZE, temp, 0, CHUNK_SIZE);

                byte[] decryptedChunk = cipher.ProcessBytes(temp);
                Array.Copy(decryptedChunk, 0, outcomingBytes, i * CHUNK_SIZE, CHUNK_SIZE);
                //Increase(IV); Why do I need to increse iv by hand?
            }

            if (blockRemaining != 0)
            {
                // Why do I need to re-init it again?
                //cipher.Init(false, new ParametersWithIV(new KeyParameter(Key), IV));

                byte[] temp = new byte[blockRemaining];
                Array.Copy(incomingBytes, incomingBytes.Length - blockRemaining, temp, 0, blockRemaining);

                byte[] decryptedChunk = cipher.DoFinal(temp);
                Array.Copy(decryptedChunk, 0, outcomingBytes, incomingBytes.Length - blockRemaining, blockRemaining);
                //Increase(IV); Why do I need to increse iv by hand?
            }

            return outcomingBytes;
   }

   private void Increase(byte[] iv)
   {
            for (var i = 0; i < iv.Length; i++)
            {
                iv[i]++;
                if (iv[i] != 0)
                {
                    break;
                }
            }
    }
}

乍一看，此代码应该可以正常工作。但事实并非如此。注意注释行： //cipher.Init(false，new ParametersWithIV（new KeyParameter（Key），IV））; 和 //增加（IV）;为什么我需要手动增加静脉注射？只有取消注释它们，我的代码才能正常工作。

我想知道为什么我必须手动增加计数器？还是我在构造函数中的某个地方设置了错误？我对Bouncy Castle不太熟悉。

P.S。我正在使用Nuget的BC 1.8.6.1版本。

C＃Bouncy Castle：AES CTR为什么它不会自动递增

0 个答案: