[英]C# AES CFB compatibility with 3rd party C implementation
我有一个用于C的第三方AES库(来自Lantronix)。 我从C#的托管代码中包装了他们的API,如下所示,并且可以正常工作:
[DllImport("cbx_enc.dll", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.Cdecl)]
static extern unsafe void VC_blockEncrypt(char* iv, char* key, int length, char* text, int RDkeyLen);
/// <summary>
/// Managed Encrypt Wrapper
/// </summary>
/// <param name="buffer">provides the plain text and receives the same length cipher text</param>
static readonly string key = "abcdef0123456789";
static readonly string iv = "0123456789ABCDEF";
public static void Encrypt(ref byte[] buffer)
{
var keyPtr = Marshal.StringToHGlobalAnsi(key);
var ivPtr = Marshal.StringToHGlobalAnsi(iv);
byte[] temp = new byte[16];
Marshal.Copy(ivPtr, temp, 0, 16);
int index = 0;
for (int i = 0; i < buffer.Length; i++)
{
if (index == 0)
{
Marshal.Copy(temp, 0, ivPtr, 16);
unsafe
{
VC_blockEncrypt((char*) ivPtr, (char*) keyPtr, 0, (char*) ivPtr, 128);
}
Marshal.Copy(ivPtr, temp, 0, 16);
index = 16;
}
temp[16 - index] ^= buffer[i];
buffer[i] = temp[16 - index];
index--;
}
Marshal.FreeHGlobal(ivPtr);
Marshal.FreeHGlobal(keyPtr);
}
现在,当我编写自己的文件时,使用System.Security.Cryptography
完全避免使用其不受管的DLL,我的最终密文似乎与它们不同! 我使用相同的模式,相同的键,相同的iv和相同的纯文本,但是算法不兼容。 下面显示的是RijndaelManaged
对象和代码的属性设置; 我是否缺少引起这种不兼容的东西?
/// <summary>
/// Managed Encrypt
/// </summary>
/// <param name="buffer">provides the plain text and receives the same length cipher text</param>
static readonly string key = "abcdef0123456789";
static readonly string iv = "0123456789ABCDEF";
public static void Encrypt(ref byte[] buffer)
{
using (RijndaelManaged cipher = new RijndaelManaged())
{
cipher.Mode = CipherMode.CFB;
cipher.Key = Encoding.ASCII.GetBytes(key);
cipher.IV = Encoding.ASCII.GetBytes(iv);
cipher.Padding = PaddingMode.None;
cipher.FeedbackSize = 128;
ICryptoTransform encryptor = cipher.CreateEncryptor(cipher.Key, cipher.IV);
using (MemoryStream msEncrypt = new MemoryStream())
{
using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
{
using (BinaryWriter swEncrypt = new BinaryWriter(csEncrypt))
{
swEncrypt.Write(buffer);
}
buffer = msEncrypt.ToArray();
}
}
}
}
另外,我从Lantronix架构中阐明的算法看起来非常简单-API进行加密,然后将输出与纯文本进行异或操作是在调用方法中完成的。 而使用.NET库,我无权访问中间加密的输出(或者有一个?),因此我可以对Lantronix加密后手动执行的方式进行XOR ...
最终目标是停止使用非托管代码,但应该能够使用完全托管的.NET代码生成相同的密文。
感谢您的帮助。
ps如果需要,我可以提供第三方C库cbx_enc.dll。
编辑 :@Topaco,这是一些要求的示例数据。 还没有从供应商那里得到关于分发DLL的消息。 正在努力...
CFB的常见输入:
byte[] buffer = Encoding.ASCII.GetBytes("AAAAAAAAAAAAAABBBBBBBBBBBBBBBBBD"); //plain text string key = "abcdef0123456789"; string iv = "0123456789ABCDEF";
从包装器到非托管DLL的I / O:
PlainText Hex: 4141414141414141414141414141424242424242424242424242424242424244
CipherText Hex: C9094F820428E07AE035B6749E18546C62F9D5FD4A78480215DA3625D376A271
来自托管代码的I / O,其中FeedbackSize = 128; //CFB128
FeedbackSize = 128; //CFB128
:
PlainText Hex: 4141414141414141414141414141424242424242424242424242424242424244
CipherText Hex: 6A1A5088ACDA505B47192093DD06CD987868BFD85278A4D7D3120CC85FCD3D83
来自托管代码的I / O,其中FeedbackSize = 8 //CFB8
:
PlainText Hex: 4141414141414141414141414141424242424242424242424242424242424244
CipherText Hex: 6ACA3B1159D38568504248CDFF159C87BB2D3850EDAEAD89493BD91087ED7507
我还使用ECB进行了附加测试,以查看其API的行为是否类似于ECB(因此需要外部XORing)。 因此,我将IV作为纯文本传递给我的ECB代码,如下所示,然后将其与第一次XOR之前的输出进行了比较-它们都不匹配!
将IV作为PlainText传递给ECB: 30313233343536373839414243444546
CipherText Hex: 2B5B11C9ED9B111A065861D29C478FDA
非托管DLL中的CipherText Hex(在第一个XOR之前): 88480EC34569A13BA174F735DF59162E
最后,这是上述测试的ECB实施:
static readonly string key = "abcdef0123456789";
static readonly string iv = "0123456789ABCDEF";
public static void Encrypt(ref byte[] buffer)
{
buffer = Encoding.ASCII.GetBytes(iv);
Console.WriteLine($"PlainText: {HexHelper.ToHexString(buffer)}");
var aes = new AesManaged
{
KeySize = 128,
Key = Encoding.ASCII.GetBytes(key),
BlockSize = 128,
Mode = CipherMode.ECB,
Padding = PaddingMode.None,
IV = new byte[] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }
};
ICryptoTransform encryptor = aes.CreateEncryptor(aes.Key, aes.IV);
buffer = encryptor.TransformFinalBlock(buffer, 0, buffer.Length);
Console.WriteLine($"CipherText: {HexHelper.ToHexString(buffer)}");
}
谢谢。
在此,我要感谢所有的帮助,尤其是@Topaco,非常感谢-您对根据文档对HEX中的纯文本进行编码的见解提供了帮助! 这是修改后的包装器代码; 如您所见,其密码现在与托管代码的密码匹配! 完善!!
static readonly string key = "61626364656630313233343536373839"; //"abcdef0123456789";
static readonly string iv = "0123456789ABCDEF";
public static void Encrypt(ref byte[] buffer)
{
Console.WriteLine($"PlainText: {HexHelper.ToHexString(buffer)}");
var keyPtr = Marshal.StringToHGlobalAnsi(key);
var ivPtr = Marshal.StringToHGlobalAnsi(iv);
byte[] temp = new byte[16];
Marshal.Copy(ivPtr, temp, 0, 16);
int index = 0;
for (int i = 0; i < buffer.Length; i++)
{
if (index == 0)
{
Marshal.Copy(temp, 0, ivPtr, 16);
unsafe
{
VC_blockEncrypt((char*) ivPtr, (char*) keyPtr, 0, (char*) ivPtr, 128);
}
Marshal.Copy(ivPtr, temp, 0, 16);
index = 16;
Console.WriteLine($"CipherText BeforeXOR: {HexHelper.ToHexString(temp)}");
}
temp[16 - index] ^= buffer[i];
buffer[i] = temp[16 - index];
index--;
}
Marshal.FreeHGlobal(ivPtr);
Marshal.FreeHGlobal(keyPtr);
Console.WriteLine($"CipherText: {HexHelper.ToHexString(buffer)}");
}
修改后的包装器代码的I / O:PlainText: 4141414141414141414141414141424242424242424242424242424242424244
CipherText: 6A1A5088ACDA505B47192093DD06CD987868BFD85278A4D7D3120CC85FCD3D83
来自托管代码的I / O:PlainText: 4141414141414141414141414141424242424242424242424242424242424244
CipherText: 6A1A5088ACDA505B47192093DD06CD987868BFD85278A4D7D3120CC85FCD3D83
干杯!!
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