c#AES解密

c# AES Decryption

提问by Steve Newton

I am working with SagePay Forms and currently converting the VB examples they have to c#. I have made good progress so the encryption part of my project works fine (SagePay can decrypt it).

我正在使用 SagePay Forms，目前正在将他们必须的 VB 示例转换为 c#。我已经取得了很好的进展，所以我的项目的加密部分工作正常（SagePay 可以解密它）。

The issue I am having is that when I attempt to decrypt the string, it turns to garbage. If anyone has done this before I would really appreciate some help with my decryption code. I have included the encryption code which works and the first two lines are the setup and call from another method.

我遇到的问题是，当我尝试解密字符串时，它变成了垃圾。如果有人之前这样做过，我真的很感激我的解密代码的帮助。我已经包含了有效的加密代码，前两行是另一种方法的设置和调用。

I haven't added the VB code but if this is required I could add it. Didn't want a huge post if not required.

我没有添加 VB 代码，但如果需要，我可以添加它。如果不需要，不想要一个巨大的帖子。

Utility Methods:

实用方法：

public string byteArrayToHexString(byte[] ba)
    {
    return BitConverter.ToString(ba).Replace("-", "");
    }

public static byte[] StringToByteArray(string hex)
    {
        return Enumerable.Range(0, hex.Length)
                         .Where(x => x % 2 == 0)
                         .Select(x => Convert.ToByte(hex.Substring(x, 2), 16))
                         .ToArray();
    }

Main Encryption Method with first couple of lines being the calling of it extracted from a larger method.

主要加密方法，前几行是从更大的方法中提取的调用。

string crypt = "blahblahblah"
string EncryptAndEncode = "@" + byteArrayToHexString(aesEncrypt(crypt));


        private byte[] aesEncrypt(string inputText)
    {

        RijndaelManaged AES = new RijndaelManaged();

        //set the mode, padding and block size for the key
        AES.Padding = PaddingMode.PKCS7;
        AES.Mode = CipherMode.CBC;
        AES.KeySize = 128;
        AES.BlockSize = 128;

        //convert key and plain text input into byte arrays
        Byte[] keyAndIvBytes = UTF8Encoding.UTF8.GetBytes("tR7nR6wZHGjYMCuV");
        Byte[] inputBytes = UTF8Encoding.UTF8.GetBytes(inputText);//AbHLlc5uLone0D1q

        //create streams and encryptor object
        MemoryStream memoryStream = new MemoryStream();
        CryptoStream cryptoStream = new CryptoStream(memoryStream, AES.CreateEncryptor(keyAndIvBytes, keyAndIvBytes), CryptoStreamMode.Write);

        //perform encryption
        cryptoStream.Write(inputBytes, 0, inputBytes.Length);
        cryptoStream.FlushFinalBlock();

        //get encrypted stream into byte array
        Byte[] outBytes = memoryStream.ToArray();

        //close streams
        memoryStream.Close();
        cryptoStream.Close();
        AES.Clear();

        return outBytes;
    }

Decoding and Decrypting methods

解码和解密方法

public string DecodeAndDecrypt(string strIn)
    {
        //** HEX decoding then AES decryption, CBC blocking with PKCS5 padding - DEFAULT **


        string DecodeAndDecrypt = aesDecrypt(StringToByteArray(strIn.Substring(1)));
        return (DecodeAndDecrypt);
    }

    private string aesDecrypt(Byte[] inputBytes)
    {
    RijndaelManaged AES = new RijndaelManaged();
    Byte[] keyAndIvBytes = UTF8Encoding.UTF8.GetBytes("tR7nR6wZHGjYMCuV");
    Byte[] outputBytes = inputBytes;//Convert.FromBase64String(inputBytes);

    //set the mode, padding and block size
    AES.Padding = PaddingMode.PKCS7;
    AES.Mode = CipherMode.CBC;
    AES.KeySize = 128;
    AES.BlockSize = 128;

    //create streams and decryptor object
    MemoryStream memoryStream = new MemoryStream(outputBytes);
    CryptoStream cryptoStream = new CryptoStream(memoryStream, AES.CreateEncryptor(keyAndIvBytes, keyAndIvBytes), CryptoStreamMode.Read);
    //perform decryption
    cryptoStream.Read(outputBytes, 0, outputBytes.Length);
    Trace.WriteLine(outputBytes);
    //close streams
    memoryStream.Close();
    cryptoStream.Close();
    AES.Clear();
    //return System.Text.Encoding.UTF8.GetString(outputBytes);

    string plainText = Encoding.UTF8.GetString(outputBytes,
                                   0,
                                   outputBytes.Length);

    return plainText;
    }

采纳答案by nerdybeardo

There are actually multiple problems with your code. First in your decrypt method you're creating an encryptor, that should be a decryptor. Secondly you're reading the entire block including the padding of your algorithm into the buffer when you do the decryption. Below is a class with the items fixed and should be returning the proper result. I do however suggest you find a better way of storing the key, putting in your code and generating it the way you'r edoing it is a no no. You should generate your key with an RNG (RNGCryptoServiceProvider) then hash it with a secure hashing algorithm such as SHA512, use that output for your key. You then need to find a good place to store it, I would look into encrypting your web.config file.

您的代码实际上存在多个问题。首先在您的解密方法中，您要创建一个加密器，它应该是一个解密器。其次，当您进行解密时，您正在读取整个块，包括将您的算法填充到缓冲区中。下面是一个带有固定项目的类，应该返回正确的结果。但是，我建议您找到一种更好的方法来存储密钥，放入您的代码并按照您的方式生成它是不行的。您应该使用 RNG (RNGCryptoServiceProvider) 生成您的密钥，然后使用安全散列算法（例如 SHA512）对其进行散列，并将该输出用于您的密钥。然后你需要找到一个好地方来存储它，我会考虑加密你的 web.config 文件。

public static class EncryptionHelper
{
    private static byte[] keyAndIvBytes;

    static EncryptionHelper()
    {
        // You'll need a more secure way of storing this, I hope this isn't
        // the real key
        keyAndIvBytes = UTF8Encoding.UTF8.GetBytes("tR7nR6wZHGjYMCuV");
    }

    public static string ByteArrayToHexString(byte[] ba)
    {
        return BitConverter.ToString(ba).Replace("-", "");
    }

    public static byte[] StringToByteArray(string hex)
    {
        return Enumerable.Range(0, hex.Length)
                         .Where(x => x % 2 == 0)
                         .Select(x => Convert.ToByte(hex.Substring(x, 2), 16))
                         .ToArray();
    }

    public static string DecodeAndDecrypt(string cipherText)
    {
        string DecodeAndDecrypt = AesDecrypt(StringToByteArray(cipherText));
        return (DecodeAndDecrypt);
    }

    public static string EncryptAndEncode(string plaintext)
    {
        return ByteArrayToHexString(AesEncrypt(plaintext));
    }

    public static string AesDecrypt(Byte[] inputBytes)
    {
        Byte[] outputBytes = inputBytes;

        string plaintext = string.Empty;

        using (MemoryStream memoryStream = new MemoryStream(outputBytes))
        {
            using (CryptoStream cryptoStream = new CryptoStream(memoryStream, GetCryptoAlgorithm().CreateDecryptor(keyAndIvBytes, keyAndIvBytes), CryptoStreamMode.Read))
            {
                using (StreamReader srDecrypt = new StreamReader(cryptoStream))
                {
                    plaintext = srDecrypt.ReadToEnd();
                }
            }
        }

        return plaintext;
    }

    public static byte[] AesEncrypt(string inputText)
    {
        byte[] inputBytes = UTF8Encoding.UTF8.GetBytes(inputText);//AbHLlc5uLone0D1q

        byte[] result = null;
        using (MemoryStream memoryStream = new MemoryStream())
        {
            using (CryptoStream cryptoStream = new CryptoStream(memoryStream, GetCryptoAlgorithm().CreateEncryptor(keyAndIvBytes, keyAndIvBytes), CryptoStreamMode.Write))
            {
                cryptoStream.Write(inputBytes, 0, inputBytes.Length);
                cryptoStream.FlushFinalBlock();

                result = memoryStream.ToArray();
            }
        }

        return result;
    }


    private static RijndaelManaged GetCryptoAlgorithm()
    {
        RijndaelManaged algorithm = new RijndaelManaged();
        //set the mode, padding and block size
        algorithm.Padding = PaddingMode.PKCS7;
        algorithm.Mode = CipherMode.CBC;
        algorithm.KeySize = 128;
        algorithm.BlockSize = 128;
        return algorithm;
    }
}

Calling it is easy:

调用它很容易：

string crypt = "blahblahblah";
string EncryptAndEncode = EncryptionHelper.EncryptAndEncode(crypt);            
Console.WriteLine(EncryptAndEncode);

Console.WriteLine(EncryptionHelper.DecodeAndDecrypt(EncryptAndEncode));

Console.ReadLine();