c# - 指定的密钥不是此算法的有效大小

Question

我有这个代码：

RijndaelManaged rijndaelCipher = new RijndaelManaged();

            // Set key and IV
            rijndaelCipher.Key = Convert.FromBase64String("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz012345678912");
            rijndaelCipher.IV = Convert.FromBase64String("1234567890123456789012345678901234567890123456789012345678901234");

我得到了抛出：

Specified key is not a valid size for this algorithm.

Specified initialization vector (IV) does not match the block size for this algorithm.

这个字符串有什么问题？我可以数一下 You 中的一些示例字符串吗？

Answer 1

当 base64 解码时，字符串“ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz012345678912”产生 48 个字节（384 位）。RijndaelManaged 支持 128、192 和 256 位密钥。

一个有效的 128 位密钥是new byte[]{ 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F }或者如果您需要从 base64 获取它：Convert.FromBase64String("AAECAwQFBgcICQoLDA0ODw==")。

默认块大小为 128 位，因此相同的字节数组将作为 IV 工作。

Answer 2

使用随机数生成器类 (RNGCryptoServiceProvider) 用随机字节填充指定的缓冲区，如下所示：

var numberOfBits = 256; // or 192 or 128, however using a larger bit size renders the encrypted data harder to decipher

var ivBytes = new byte[numberOfBits / 8]; // 8 bits per byte

new RNGCryptoServiceProvider().GetBytes(ivBytes);

var rijndaelManagedCipher = new RijndaelManaged();

//Don't forget to set the explicitly set the block size for the IV if you're not using the default of 128

rijndaelManagedCipher.BlockSize = 256;

rijndaelManagedCipher.IV = ivBytes;

请注意，相同的过程可用于派生密钥。希望这可以帮助。

Answer 3

RijndaelManaged 算法支持 128、192 或 256 位的密钥长度。您的钥匙是这些尺寸之一吗？

Answer 4

这是我创建的课程

public class ByteCipher
{
    // This constant is used to determine the keysize of the encryption algorithm in bits.
    // We divide this by 8 within the code below to get the equivalent number of bytes.
    private int _Keysize = (int)GlobalConfiguration.DataEncode_Key_Size;

    private byte[] saltStringBytes;

    private byte[] ivStringBytes;
    // This constant determines the number of iterations for the password bytes generation function.
    private const int DerivationIterations = 1000;
    private string _passPhrase = GlobalConfiguration.DataEncode_Key;

    private const string salt128 = "kljsdkkdlo4454GG";
    private const string salt256 = "kljsdkkdlo4454GG00155sajuklmbkdl";

    public ByteCipher(string passPhrase = null, DataCipherKeySize keySize = DataCipherKeySize.Key_128)
    {
        if (!string.IsNullOrEmpty(passPhrase?.Trim()))
            _passPhrase = passPhrase;
        _Keysize = keySize == DataCipherKeySize.Key_256 ? 256 : 128;
        saltStringBytes = _Keysize == 256 ? Encoding.UTF8.GetBytes(salt256) : Encoding.UTF8.GetBytes(salt128);
        ivStringBytes = _Keysize == 256 ? Encoding.UTF8.GetBytes("SSljsdkkdlo4454Maakikjhsd55GaRTP") : Encoding.UTF8.GetBytes("SSljsdkkdlo4454M");
    }

    public byte[] Encrypt(byte[] plainTextBytes)
    {
        if (plainTextBytes.Length <= 0)
            return plainTextBytes;

        using (var password = new Rfc2898DeriveBytes(_passPhrase, saltStringBytes, DerivationIterations))
        {
            var keyBytes = password.GetBytes(_Keysize / 8);
            using (var symmetricKey = new RijndaelManaged())
            {
                symmetricKey.BlockSize = _Keysize;
                symmetricKey.Mode = CipherMode.CBC;
                symmetricKey.Padding = PaddingMode.PKCS7;
                using (var encryptor = symmetricKey.CreateEncryptor(keyBytes, ivStringBytes))
                {
                    using (var memoryStream = new MemoryStream())
                    {
                        using (var cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write))
                        {
                            cryptoStream.Write(plainTextBytes, 0, plainTextBytes.Length);
                            cryptoStream.FlushFinalBlock();
                            // Create the final bytes as a concatenation of the random salt bytes, the random iv bytes and the cipher bytes.
                            var cipherTextBytes = saltStringBytes;
                            cipherTextBytes = cipherTextBytes.Concat(ivStringBytes).ToArray();
                            cipherTextBytes = cipherTextBytes.Concat(memoryStream.ToArray()).ToArray();
                            memoryStream.Close();
                            cryptoStream.Close();
                            return cipherTextBytes;
                        }
                    }
                }
            }
        }
    }

    public byte[] Decrypt(byte[] cipherTextBytesWithSaltAndIv)
    {
        if (cipherTextBytesWithSaltAndIv.Length <= 0)
            return cipherTextBytesWithSaltAndIv;
        var v = Encoding.UTF8.GetString(cipherTextBytesWithSaltAndIv.Take(_Keysize / 8).ToArray());
        if (v != salt256 && v != salt128)
            return cipherTextBytesWithSaltAndIv;

        var cipherTextBytes = cipherTextBytesWithSaltAndIv.Skip((_Keysize / 8) * 2).Take(cipherTextBytesWithSaltAndIv.Length - ((_Keysize / 8) * 2)).ToArray();

        using (var password = new Rfc2898DeriveBytes(_passPhrase, saltStringBytes, DerivationIterations))
        {
            var keyBytes = password.GetBytes(_Keysize / 8);
            using (var symmetricKey = new RijndaelManaged())
            {
                symmetricKey.Mode = CipherMode.CBC;
                symmetricKey.Padding = PaddingMode.PKCS7;
                symmetricKey.BlockSize = _Keysize;

                using (var decryptor = symmetricKey.CreateDecryptor(keyBytes, ivStringBytes))
                {
                    using (var memoryStream = new MemoryStream(cipherTextBytes))
                    {
                        using (var cryptoStream = new CryptoStream(memoryStream, decryptor, CryptoStreamMode.Read))
                        {
                            var plainTextBytes = new byte[cipherTextBytes.Length];
                            var decryptedByteCount = cryptoStream.Read(plainTextBytes, 0, plainTextBytes.Length);
                            memoryStream.Close();
                            cryptoStream.Close();
                            return plainTextBytes;
                        }
                    }
                }
            }
        }
    }
}

Answer 5

我不知道 rijndaelCipher.Key 的长度如果是 24，那么 rijndaelCipher.Key = s.SubString(0, 24);

太简单。