C# AES-CBC中的填充
我正在尝试使用C#中的（128位AES）随机IV测试CBC 在我要解决的问题中，我有12字节的输入消息。条件是，如果纯文本小于块大小（16字节），则要使用的填充从0x01开始，然后最多为6 0x00 示例：C# AES-CBC中的填充,c#,cryptography,encryption-symmetric,rijndaelmanaged,cbc-mode,C#,Cryptography,Encryption Symmetric,Rijndaelmanaged,Cbc Mode,我正在尝试使用C#中的（128位AES）随机IV测试CBC 在我要解决的问题中，我有12字节的输入消息。条件是，如果纯文本小于块大小（16字节），则要使用的填充从0x01开始，然后最多为6 0x00 示例： in ASCII PT = Pay Bob 100% in hex PT = 50 61 79 20 42 6f 62 20 31 30 30 24 PT with Padding = 50 61 79 20 42 6f 62 20 31 30 30 24 01 00
in ASCII PT = Pay Bob 100%
in hex PT = 50 61 79 20 42 6f 62 20 31 30 30 24
PT with Padding = 50 61 79 20 42 6f 62 20 31 30 30 24 01 00 00 00
public class CBC
{
public CBC()
{
}
private static readonly byte[] SALT = new byte[]
{0x26, 0xdc, 0xff, 0x00, 0xad, 0xed, 0x7a, 0xee, 0xc5, 0xfe, 0x07, 0xaf, 0x4d, 0x08, 0x22, 0x3c};
public static byte[] EncryptCBC(string plainText, string passPhrase, PaddingMode paddingMode )
{
byte[] result;
using (RijndaelManaged cryptoProvider = new RijndaelManaged())
{
Rfc2898DeriveBytes derivedKey = new Rfc2898DeriveBytes(passPhrase, SALT);
cryptoProvider.Mode = CipherMode.CBC;
cryptoProvider.GenerateIV(); // generate random IV
cryptoProvider.Padding = paddingMode;
cryptoProvider.Key = derivedKey.GetBytes(cryptoProvider.KeySize / 8);
using (MemoryStream msEncrypt = new MemoryStream())
{
using (ICryptoTransform encryptor = cryptoProvider.CreateEncryptor(cryptoProvider.Key, cryptoProvider.IV))
{
using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
{
using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
{
swEncrypt.Write(plainText);
}
}
}
// concatenate iv to ciphertext
result = cryptoProvider.IV.Concat(msEncrypt.ToArray()).ToArray();
}
cryptoProvider.Clear();
}
return result;
}
public static string DecryptCBC(byte[] cipherTextBytes, string passPhrase, PaddingMode paddingMode)
{
string result = null;
using (RijndaelManaged cryptoProvider = new RijndaelManaged())
{
Rfc2898DeriveBytes derivedKey = new Rfc2898DeriveBytes(passPhrase, SALT);
cryptoProvider.Mode = CipherMode.CBC;
// take the iv off the beginning of the ciphertext message
cryptoProvider.IV = cipherTextBytes.Take(cryptoProvider.BlockSize / 8).ToArray();
cryptoProvider.Padding = paddingMode;//PaddingMode.ANSIX923;
cryptoProvider.Key = derivedKey.GetBytes(cryptoProvider.KeySize / 8);
using (MemoryStream msEncrypt = new MemoryStream(cipherTextBytes.Skip(cryptoProvider.BlockSize / 8).ToArray())) // skip the IV bytes
{
using (ICryptoTransform encryptor = cryptoProvider.CreateDecryptor(cryptoProvider.Key, cryptoProvider.IV))
{
using (CryptoStream cryptoStream = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Read))
{
byte[] plainTextBytes = new byte[cipherTextBytes.Length - cryptoProvider.BlockSize / 8];
int decryptedByteCount = cryptoStream.Read(plainTextBytes, 0, plainTextBytes.Length);
result = Encoding.UTF8.GetString(plainTextBytes, 0, decryptedByteCount);
cryptoStream.Close();
}
}
}
cryptoProvider.Clear();
}
return result;
}
}
- 可变长度填充
in ASCII PT = Pay Bob 100%
in hex PT = 50 61 79 20 42 6f 62 20 31 30 30 24
PT with Padding = 50 61 79 20 42 6f 62 20 31 30 30 24 01 00 00 00
public class CBC
{
public CBC()
{
}
private static readonly byte[] SALT = new byte[]
{0x26, 0xdc, 0xff, 0x00, 0xad, 0xed, 0x7a, 0xee, 0xc5, 0xfe, 0x07, 0xaf, 0x4d, 0x08, 0x22, 0x3c};
public static byte[] EncryptCBC(string plainText, string passPhrase, PaddingMode paddingMode )
{
byte[] result;
using (RijndaelManaged cryptoProvider = new RijndaelManaged())
{
Rfc2898DeriveBytes derivedKey = new Rfc2898DeriveBytes(passPhrase, SALT);
cryptoProvider.Mode = CipherMode.CBC;
cryptoProvider.GenerateIV(); // generate random IV
cryptoProvider.Padding = paddingMode;
cryptoProvider.Key = derivedKey.GetBytes(cryptoProvider.KeySize / 8);
using (MemoryStream msEncrypt = new MemoryStream())
{
using (ICryptoTransform encryptor = cryptoProvider.CreateEncryptor(cryptoProvider.Key, cryptoProvider.IV))
{
using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
{
using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
{
swEncrypt.Write(plainText);
}
}
}
// concatenate iv to ciphertext
result = cryptoProvider.IV.Concat(msEncrypt.ToArray()).ToArray();
}
cryptoProvider.Clear();
}
return result;
}
public static string DecryptCBC(byte[] cipherTextBytes, string passPhrase, PaddingMode paddingMode)
{
string result = null;
using (RijndaelManaged cryptoProvider = new RijndaelManaged())
{
Rfc2898DeriveBytes derivedKey = new Rfc2898DeriveBytes(passPhrase, SALT);
cryptoProvider.Mode = CipherMode.CBC;
// take the iv off the beginning of the ciphertext message
cryptoProvider.IV = cipherTextBytes.Take(cryptoProvider.BlockSize / 8).ToArray();
cryptoProvider.Padding = paddingMode;//PaddingMode.ANSIX923;
cryptoProvider.Key = derivedKey.GetBytes(cryptoProvider.KeySize / 8);
using (MemoryStream msEncrypt = new MemoryStream(cipherTextBytes.Skip(cryptoProvider.BlockSize / 8).ToArray())) // skip the IV bytes
{
using (ICryptoTransform encryptor = cryptoProvider.CreateDecryptor(cryptoProvider.Key, cryptoProvider.IV))
{
using (CryptoStream cryptoStream = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Read))
{
byte[] plainTextBytes = new byte[cipherTextBytes.Length - cryptoProvider.BlockSize / 8];
int decryptedByteCount = cryptoStream.Read(plainTextBytes, 0, plainTextBytes.Length);
result = Encoding.UTF8.GetString(plainTextBytes, 0, decryptedByteCount);
cryptoStream.Close();
}
}
}
cryptoProvider.Clear();
}
return result;
}
}
private byte[] PaddPlainTextBytes(byte[] plainTextBytes )
{
byte[] padding = utils.HexToBytes("01000000");
MemoryStream s = new MemoryStream();
s.Write(plainTextBytes, 0, plainTextBytes.Length);
s.Write(padding, 0, padding.Length);
byte[] paddedPt = s.ToArray();
return paddedPt;
}
private void btnTestCBC_Click(object sender, EventArgs e)
{
string plainText = "Pay Bob 100%";
string passPhrase = "Thisismypassphrase";
ShowMessage(@"Plain Text = " + plainText);
byte[] pBytes = PaddPlainTextBytes(Encoding.ASCII.GetBytes(plainText));
string message = Encoding.ASCII.GetString(pBytes);
byte[] encryptedBytes = CBC.EncryptCBC(plainText: message, passPhrase: passPhrase, paddingMode: PaddingMode.None);
ShowMessage("Encrypted String = " + Encoding.ASCII.GetString(encryptedBytes));
ShowMessage("Encrypted HEX = " + utils.BytesToHex(encryptedBytes));
string decryptedString = CBC.DecryptCBC(encryptedBytes, passPhrase, PaddingMode.None);
ShowMessage("Deccrypted String = " + decryptedString);
}
我不熟悉您的填充方案，但它肯定不是内置在.net中的。您应该能够将
PaddingModeNonePaddingModeNone此填充节点可能不是内置的。如果你想进行实验，我建议你使用Bouncy Castle LIB，否则就改用几乎无处不在的PKCS#7填充。你所描述的填充方案看起来很像，请参阅维基百科页面上的填充（我刚刚编辑过）了解填充方法。通常，您首先将一个位设置为1，而不是一个字节，因此第一个字节将是0x80，而不是0x01
此填充节点可能不是内置的。如果您想进行实验，我建议您使用Bouncy Castle LIB，否则请切换到几乎无处不在的PKCS#7填充。您也可以使用不需要填充的操作模式，如CTR。唉，这不是内置的。您似乎认为填充始终是固定长度，而不是对齐功能。您还可以使用不需要填充的操作模式，如CTR。不是内置的，唉。您似乎认为填充始终是固定长度的，而不是对齐函数。您的输出工作正常，您的问题是，填充函数不工作可变长度的消息。
100..00”。不做选择的密文攻击作业，第一个问题是如何在c#中进行某种填充，修改后的问题不是堆栈溢出问题，如果您问的问题确实与CBC的工作方式有关，则可能是crypto.stackoverflow问题。那么我如何将此问题移至crypto.stackoverflow？将此问题还原为有关填充的问题，然后问一个关于加密的新问题，关于如何用填充方案修改CBC加密的填充块。我已经更新了这个问题。你能为处理最后一个块的可变长度的填充函数提供一个例子吗？你的输出有效，你的问题是，填充函数不能处理可变长度的消息在100..00
中没有“。
”。没有做选择的密文攻击作业，第一个问题是如何在c#中进行某种填充，修改后的问题不是堆栈溢出问题，如果您问的问题确实与CBC的工作方式有关，则可能是crypto.stackoverflow问题。那么我如何将此问题移至crypto.stackoverflow？将此问题还原为有关填充的问题，然后问一个关于加密的新问题，关于如何用填充方案修改CBC加密的填充块。我已经更新了这个问题。你能提供一个处理最后一块可变长度的填充函数的例子吗？@KhurramMajeed谢谢，从我的智能手机上发布，难以编辑：）@KhurramMajeed谢谢，从我的智能手机上发布，难以编辑：）