指定的初始化向量（IV）与该算法的块大小不匹配 [英] The specified initialization vector (IV) does not match the block size for this algorithm
本文介绍了指定的初始化向量（IV）与该算法的块大小不匹配的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我正在尝试使用示例 RinjaelManaged加密类（请参阅：在C＃中加密和解密字符串）以改为使用AesCryptoServiceProvider，以便它可以在设置为使用的计算机上运行
I'm trying to adapt an example RinjaelManaged encryption class (see: Encrypting & Decrypting a String in C#) to instead use the AesCryptoServiceProvider so it can run on computers set to use only FIPS compliant algorithms.
但是，这似乎不像交换类名那样简单，因为我现在收到有关初始化向量长度的错误。我意识到已经有一些问题了，但是在我的特定用例中尝试使用其他问题的答案并没有成功。
However it seems it's not as simple as swapping out the class names as I now get an error about the length of the Initialization Vector. I realise there are several questions about this already but I've been unsuccessful with trying to use the answers from other questions in my particular use case.
我需要做什么更改以获取IV长度以匹配所需的长度？
What do I need to change to get the IV length to match what's needed?
namespace Encryption
{
#region Using Statements
using System;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
#endregion
public class EncryptionHelper
{
#region Private Fields
// This constant determines the number of iterations for the password bytes generation function.
private const int DerivationIterations = 1000;
// 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 const int KeySize = 256;
private const int BlockSize = 128;
#endregion Private Fields
#region Public Methods
/// <summary>Decrypts the specified cipher text.</summary>
/// <param name="cipherText">The cipher text.</param>
/// <param name="passPhrase">The pass phrase.</param>
/// <returns></returns>
public static string Decrypt(string cipherText, string passPhrase)
{
// Get the complete stream of bytes that represent:
// [32 bytes of Salt] + [32 bytes of IV] + [n bytes of CipherText]
byte[] cipherTextBytesWithSaltAndIv = Convert.FromBase64String(cipherText);
// Get the saltbytes by extracting the first 32 bytes from the supplied cipherText bytes.
byte[] saltStringBytes = cipherTextBytesWithSaltAndIv.Take(KeySize / 8).ToArray();
// Get the IV bytes by extracting the next 32 bytes from the supplied cipherText bytes.
byte[] ivStringBytes = cipherTextBytesWithSaltAndIv.Skip(KeySize / 8).Take(KeySize / 8).ToArray();
// Get the actual cipher text bytes by removing the first 64 bytes from the cipherText string.
byte[] cipherTextBytes = cipherTextBytesWithSaltAndIv.Skip(KeySize / 8 * 2).Take(cipherTextBytesWithSaltAndIv.Length - KeySize / 8 * 2).ToArray();
using (var password = new Rfc2898DeriveBytes(passPhrase, saltStringBytes, DerivationIterations))
{
byte[] keyBytes = password.GetBytes(KeySize / 8);
using (var aes = new AesCryptoServiceProvider())
{
aes.BlockSize = BlockSize;
aes.Mode = CipherMode.CBC;
aes.Padding = PaddingMode.PKCS7;
using (ICryptoTransform decryptor = aes.CreateDecryptor(keyBytes, ivStringBytes))
using (var memoryStream = new MemoryStream(cipherTextBytes))
using (var cryptoStream = new CryptoStream(memoryStream, decryptor, CryptoStreamMode.Read))
{
var plainTextBytes = new byte[cipherTextBytes.Length];
int decryptedByteCount = cryptoStream.Read(plainTextBytes, 0, plainTextBytes.Length);
memoryStream.Close();
cryptoStream.Close();
return Encoding.UTF8.GetString(plainTextBytes, 0, decryptedByteCount);
}
}
}
}
/// <summary>Encrypts the specified plain text.</summary>
/// <param name="plainText">The plain text.</param>
/// <param name="passPhrase">The pass phrase.</param>
/// <returns></returns>
public static string Encrypt(string plainText, string passPhrase)
{
// Salt and IV is randomly generated each time, but is preprended to encrypted cipher text
// so that the same Salt and IV values can be used when decrypting.
byte[] saltStringBytes = Generate256BitsOfRandomEntropy();
byte[] ivStringBytes = Generate256BitsOfRandomEntropy();
byte[] plainTextBytes = Encoding.UTF8.GetBytes(plainText);
using (var password = new Rfc2898DeriveBytes(passPhrase, saltStringBytes, DerivationIterations))
{
byte[] keyBytes = password.GetBytes(KeySize / 8);
using (var symmetricKey = new AesCryptoServiceProvider())
{
symmetricKey.BlockSize = BlockSize;
symmetricKey.Mode = CipherMode.CBC;
symmetricKey.Padding = PaddingMode.PKCS7;
using (ICryptoTransform 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.
byte[] cipherTextBytes = saltStringBytes;
cipherTextBytes = cipherTextBytes.Concat(ivStringBytes).ToArray();
cipherTextBytes = cipherTextBytes.Concat(memoryStream.ToArray()).ToArray();
memoryStream.Close();
cryptoStream.Close();
return Convert.ToBase64String(cipherTextBytes);
}
}
}
}
}
}
#endregion Public Methods
#region Private Methods
/// <summary>Generate256s the bits of random entropy.</summary>
/// <returns></returns>
private static byte[] Generate256BitsOfRandomEntropy()
{
var randomBytes = new byte[32]; // 32 Bytes will give us 256 bits.
using (var rngCsp = new RNGCryptoServiceProvider())
{
// Fill the array with cryptographically secure random bytes.
rngCsp.GetBytes(randomBytes);
}
return randomBytes;
}
#endregion Private Methods
}
}
推荐答案
好吧，我最终通过将IV长度与Salt长度清楚地分开来解决了这个问题：
OK I eventually got to the bottom of it by clearly separating the IV length from the Salt length:
public class EncryptionHelper
{
#region Private Fields
// This constant determines the number of iterations for the password bytes generation function.
private const int DerivationIterations = 1000;
// 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 const int saltBytes = 32; // bytes
private const int ivBytes = 16; // bytes
#endregion Private Fields
#region Public Methods
/// <summary>Decrypts the specified cipher text.</summary>
/// <param name="cipherText">The cipher text.</param>
/// <param name="passPhrase">The pass phrase.</param>
/// <returns></returns>
public static string Decrypt(string cipherText, string passPhrase)
{
// Get the complete stream of bytes that represent:
// [32 bytes of Salt] + [16 bytes of IV] + [n bytes of CipherText]
byte[] cipherTextBytesWithSaltAndIv = Convert.FromBase64String(cipherText);
// Get the saltbytes by extracting the first 32 bytes from the supplied cipherText bytes.
byte[] saltStringBytes = cipherTextBytesWithSaltAndIv.Take(saltBytes).ToArray();
// Get the IV bytes by extracting the next 32 bytes from the supplied cipherText bytes.
byte[] ivStringBytes = cipherTextBytesWithSaltAndIv.Skip(saltBytes).Take(ivBytes).ToArray();
// Get the actual cipher text bytes by removing the first 48 bytes from the cipherText string.
byte[] cipherTextBytes = cipherTextBytesWithSaltAndIv.Skip(saltBytes + ivBytes).Take(cipherTextBytesWithSaltAndIv.Length - (saltBytes + ivBytes)).ToArray();
using (var password = new Rfc2898DeriveBytes(passPhrase, saltStringBytes, DerivationIterations))
{
byte[] keyBytes = password.GetBytes(saltBytes);
using (var symmetricKey = new AesCryptoServiceProvider())
{
symmetricKey.BlockSize = 128;
symmetricKey.Mode = CipherMode.CBC;
symmetricKey.Padding = PaddingMode.PKCS7;
using (ICryptoTransform 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];
int decryptedByteCount = cryptoStream.Read(plainTextBytes, 0, plainTextBytes.Length);
memoryStream.Close();
cryptoStream.Close();
return Encoding.UTF8.GetString(plainTextBytes, 0, decryptedByteCount);
}
}
}
}
/// <summary>Encrypts the specified plain text.</summary>
/// <param name="plainText">The plain text.</param>
/// <param name="passPhrase">The pass phrase.</param>
/// <returns></returns>
public static string Encrypt(string plainText, string passPhrase)
{
// Salt and IV is randomly generated each time, but is preprended to encrypted cipher text
// so that the same Salt and IV values can be used when decrypting.
byte[] saltStringBytes = GenerateBitsOfRandomEntropy(32);
byte[] ivStringBytes = GenerateBitsOfRandomEntropy(16);
byte[] plainTextBytes = Encoding.UTF8.GetBytes(plainText);
using (var password = new Rfc2898DeriveBytes(passPhrase, saltStringBytes, DerivationIterations))
{
byte[] keyBytes = password.GetBytes(saltBytes);
using (var symmetricKey = new AesCryptoServiceProvider())
{
symmetricKey.BlockSize = 128;
symmetricKey.Mode = CipherMode.CBC;
symmetricKey.Padding = PaddingMode.PKCS7;
using (ICryptoTransform 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.
byte[] cipherTextBytes = saltStringBytes;
cipherTextBytes = cipherTextBytes.Concat(ivStringBytes).ToArray();
cipherTextBytes = cipherTextBytes.Concat(memoryStream.ToArray()).ToArray();
memoryStream.Close();
cryptoStream.Close();
return Convert.ToBase64String(cipherTextBytes);
}
}
}
}
}
}
#endregion Public Methods
#region Private Methods
/// <summary>Generate bits of random entropy.</summary>
/// <returns></returns>
private static byte[] GenerateBitsOfRandomEntropy(int num)
{
var randomBytes = new byte[num]; // 32 Bytes will give us 256 bits.
using (var rngCsp = new RNGCryptoServiceProvider())
{
// Fill the array with cryptographically secure random bytes.
rngCsp.GetBytes(randomBytes);
}
return randomBytes;
}
#endregion Private Methods
这篇关于指定的初始化向量（IV）与该算法的块大小不匹配的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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