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Improved AES implementation #450

This commit is contained in:
MaxXor 2016-05-16 22:04:20 +02:00
parent 28e0cf5cdf
commit d58cc00156
2 changed files with 160 additions and 28 deletions
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94
Client/Core/Cryptography/AES.cs
View File

@ -5,17 +5,25 @@ using System.Text;
namespace xClient.Core.Cryptography
{
// ReSharper disable once InconsistentNaming
public static class AES
{
private const int IVLENGTH = 16;
private const int IvLength = 16;
private const int HmacSha256Length = 32;
private static byte[] _defaultKey;
private static byte[] _defaultAuthKey;
private static readonly byte[] Salt =
{
0xBF, 0xEB, 0x1E, 0x56, 0xFB, 0xCD, 0x97, 0x3B, 0xB2, 0x19, 0x2, 0x24, 0x30, 0xA5, 0x78, 0x43, 0x0, 0x3D, 0x56,
0x44, 0xD2, 0x1E, 0x62, 0xB9, 0xD4, 0xF1, 0x80, 0xE7, 0xE6, 0xC3, 0x39, 0x41
};
public static void SetDefaultKey(string key)
{
using (var md5 = new MD5CryptoServiceProvider())
using (Rfc2898DeriveBytes derive = new Rfc2898DeriveBytes(key, Salt, 2000))
{
_defaultKey = md5.ComputeHash(Encoding.UTF8.GetBytes(key));
_defaultKey = derive.GetBytes(16);
_defaultAuthKey = derive.GetBytes(64);
}
}
@ -29,6 +37,12 @@ namespace xClient.Core.Cryptography
return Convert.ToBase64String(Encrypt(Encoding.UTF8.GetBytes(input)));
}
/* FORMAT
* ----------------------------------------
* | HMAC | IV | CIPHERTEXT |
* ----------------------------------------
* 32 bytes 16 bytes
*/
public static byte[] Encrypt(byte[] input)
{
if (_defaultKey == null || _defaultKey.Length == 0) throw new Exception("Key can not be empty.");
@ -40,14 +54,28 @@ namespace xClient.Core.Cryptography
{
using (var ms = new MemoryStream())
{
using (var aesProvider = new AesCryptoServiceProvider() { Key = _defaultKey })
ms.Position = HmacSha256Length; // reserve first 32 bytes for HMAC
using (var aesProvider = new AesCryptoServiceProvider())
{
aesProvider.KeySize = 128;
aesProvider.BlockSize = 128;
aesProvider.Mode = CipherMode.CBC;
aesProvider.Padding = PaddingMode.PKCS7;
aesProvider.Key = _defaultKey;
aesProvider.GenerateIV();
using (var cs = new CryptoStream(ms, aesProvider.CreateEncryptor(), CryptoStreamMode.Write))
{
ms.Write(aesProvider.IV, 0, aesProvider.IV.Length); // write first 16 bytes IV, followed by encrypted message
ms.Write(aesProvider.IV, 0, aesProvider.IV.Length); // write next 16 bytes the IV, followed by ciphertext
cs.Write(data, 0, data.Length);
cs.FlushFinalBlock();
using (var hmac = new HMACSHA256(_defaultAuthKey))
{
byte[] hash = hmac.ComputeHash(ms.ToArray(), HmacSha256Length, ms.ToArray().Length - HmacSha256Length); // compute the HMAC of IV and ciphertext
ms.Position = 0; // write hash at beginning
ms.Write(hash, 0, hash.Length);
}
}
}
@ -64,9 +92,11 @@ namespace xClient.Core.Cryptography
{
if (key == null || key.Length == 0) throw new Exception("Key can not be empty.");
using (var md5 = new MD5CryptoServiceProvider())
byte[] authKey;
using (Rfc2898DeriveBytes derive = new Rfc2898DeriveBytes(key, Salt, 2000))
{
key = md5.ComputeHash(key);
key = derive.GetBytes(16);
authKey = derive.GetBytes(64);
}
byte[] data = input, encdata = new byte[0];
@ -75,14 +105,28 @@ namespace xClient.Core.Cryptography
{
using (var ms = new MemoryStream())
{
using (var aesProvider = new AesCryptoServiceProvider() { Key = key })
ms.Position = HmacSha256Length; // reserve first 32 bytes for HMAC
using (var aesProvider = new AesCryptoServiceProvider())
{
aesProvider.KeySize = 128;
aesProvider.BlockSize = 128;
aesProvider.Mode = CipherMode.CBC;
aesProvider.Padding = PaddingMode.PKCS7;
aesProvider.Key = key;
aesProvider.GenerateIV();
using (var cs = new CryptoStream(ms, aesProvider.CreateEncryptor(), CryptoStreamMode.Write))
{
ms.Write(aesProvider.IV, 0, aesProvider.IV.Length); // write first 16 bytes IV, followed by encrypted message
ms.Write(aesProvider.IV, 0, aesProvider.IV.Length); // write next 16 bytes the IV, followed by ciphertext
cs.Write(data, 0, data.Length);
cs.FlushFinalBlock();
using (var hmac = new HMACSHA256(authKey))
{
byte[] hash = hmac.ComputeHash(ms.ToArray(), HmacSha256Length, ms.ToArray().Length - HmacSha256Length); // compute the HMAC of IV and ciphertext
ms.Position = 0; // write hash at beginning
ms.Write(hash, 0, hash.Length);
}
}
}
@ -111,15 +155,37 @@ namespace xClient.Core.Cryptography
{
using (var ms = new MemoryStream(input))
{
using (var aesProvider = new AesCryptoServiceProvider() { Key = _defaultKey })
using (var aesProvider = new AesCryptoServiceProvider())
{
byte[] iv = new byte[IVLENGTH];
ms.Read(iv, 0, IVLENGTH); // read first 16 bytes for IV, followed by encrypted message
aesProvider.KeySize = 128;
aesProvider.BlockSize = 128;
aesProvider.Mode = CipherMode.CBC;
aesProvider.Padding = PaddingMode.PKCS7;
aesProvider.Key = _defaultKey;
// read first 32 bytes for HMAC
using (var hmac = new HMACSHA256(_defaultAuthKey))
{
var hash = hmac.ComputeHash(ms.ToArray(), HmacSha256Length, ms.ToArray().Length - HmacSha256Length);
byte[] receivedHash = new byte[HmacSha256Length];
ms.Read(receivedHash, 0, receivedHash.Length);
for (int i = 0; i < hash.Length; i++)
{
if (receivedHash[i] != hash[i])
{
return data;
}
}
}
byte[] iv = new byte[IvLength];
ms.Read(iv, 0, IvLength); // read next 16 bytes for IV, followed by ciphertext
aesProvider.IV = iv;
using (var cs = new CryptoStream(ms, aesProvider.CreateDecryptor(), CryptoStreamMode.Read))
{
byte[] temp = new byte[ms.Length - IVLENGTH + 1];
byte[] temp = new byte[ms.Length - IvLength + 1];
data = new byte[cs.Read(temp, 0, temp.Length)];
Buffer.BlockCopy(temp, 0, data, 0, data.Length);
}

94
Server/Core/Cryptography/AES.cs
View File

@ -5,17 +5,25 @@ using System.Text;
namespace xServer.Core.Cryptography
{
// ReSharper disable once InconsistentNaming
public static class AES
{
private const int IVLENGTH = 16;
private const int IvLength = 16;
private const int HmacSha256Length = 32;
private static byte[] _defaultKey;
private static byte[] _defaultAuthKey;
private static readonly byte[] Salt =
{
0xBF, 0xEB, 0x1E, 0x56, 0xFB, 0xCD, 0x97, 0x3B, 0xB2, 0x19, 0x2, 0x24, 0x30, 0xA5, 0x78, 0x43, 0x0, 0x3D, 0x56,
0x44, 0xD2, 0x1E, 0x62, 0xB9, 0xD4, 0xF1, 0x80, 0xE7, 0xE6, 0xC3, 0x39, 0x41
};
public static void SetDefaultKey(string key)
{
using (var md5 = new MD5CryptoServiceProvider())
using (Rfc2898DeriveBytes derive = new Rfc2898DeriveBytes(key, Salt, 2000))
{
_defaultKey = md5.ComputeHash(Encoding.UTF8.GetBytes(key));
_defaultKey = derive.GetBytes(16);
_defaultAuthKey = derive.GetBytes(64);
}
}
@ -29,6 +37,12 @@ namespace xServer.Core.Cryptography
return Convert.ToBase64String(Encrypt(Encoding.UTF8.GetBytes(input)));
}
/* FORMAT
* ----------------------------------------
* | HMAC | IV | CIPHERTEXT |
* ----------------------------------------
* 32 bytes 16 bytes
*/
public static byte[] Encrypt(byte[] input)
{
if (_defaultKey == null || _defaultKey.Length == 0) throw new Exception("Key can not be empty.");
@ -40,14 +54,28 @@ namespace xServer.Core.Cryptography
{
using (var ms = new MemoryStream())
{
using (var aesProvider = new AesCryptoServiceProvider() { Key = _defaultKey })
ms.Position = HmacSha256Length; // reserve first 32 bytes for HMAC
using (var aesProvider = new AesCryptoServiceProvider())
{
aesProvider.KeySize = 128;
aesProvider.BlockSize = 128;
aesProvider.Mode = CipherMode.CBC;
aesProvider.Padding = PaddingMode.PKCS7;
aesProvider.Key = _defaultKey;
aesProvider.GenerateIV();
using (var cs = new CryptoStream(ms, aesProvider.CreateEncryptor(), CryptoStreamMode.Write))
{
ms.Write(aesProvider.IV, 0, aesProvider.IV.Length); // write first 16 bytes IV, followed by encrypted message
ms.Write(aesProvider.IV, 0, aesProvider.IV.Length); // write next 16 bytes the IV, followed by ciphertext
cs.Write(data, 0, data.Length);
cs.FlushFinalBlock();
using (var hmac = new HMACSHA256(_defaultAuthKey))
{
byte[] hash = hmac.ComputeHash(ms.ToArray(), HmacSha256Length, ms.ToArray().Length - HmacSha256Length); // compute the HMAC of IV and ciphertext
ms.Position = 0; // write hash at beginning
ms.Write(hash, 0, hash.Length);
}
}
}
@ -64,9 +92,11 @@ namespace xServer.Core.Cryptography
{
if (key == null || key.Length == 0) throw new Exception("Key can not be empty.");
using (var md5 = new MD5CryptoServiceProvider())
byte[] authKey;
using (Rfc2898DeriveBytes derive = new Rfc2898DeriveBytes(key, Salt, 2000))
{
key = md5.ComputeHash(key);
key = derive.GetBytes(16);
authKey = derive.GetBytes(64);
}
byte[] data = input, encdata = new byte[0];
@ -75,14 +105,28 @@ namespace xServer.Core.Cryptography
{
using (var ms = new MemoryStream())
{
using (var aesProvider = new AesCryptoServiceProvider() { Key = key })
ms.Position = HmacSha256Length; // reserve first 32 bytes for HMAC
using (var aesProvider = new AesCryptoServiceProvider())
{
aesProvider.KeySize = 128;
aesProvider.BlockSize = 128;
aesProvider.Mode = CipherMode.CBC;
aesProvider.Padding = PaddingMode.PKCS7;
aesProvider.Key = key;
aesProvider.GenerateIV();
using (var cs = new CryptoStream(ms, aesProvider.CreateEncryptor(), CryptoStreamMode.Write))
{
ms.Write(aesProvider.IV, 0, aesProvider.IV.Length); // write first 16 bytes IV, followed by encrypted message
ms.Write(aesProvider.IV, 0, aesProvider.IV.Length); // write next 16 bytes the IV, followed by ciphertext
cs.Write(data, 0, data.Length);
cs.FlushFinalBlock();
using (var hmac = new HMACSHA256(authKey))
{
byte[] hash = hmac.ComputeHash(ms.ToArray(), HmacSha256Length, ms.ToArray().Length - HmacSha256Length); // compute the HMAC of IV and ciphertext
ms.Position = 0; // write hash at beginning
ms.Write(hash, 0, hash.Length);
}
}
}
@ -111,15 +155,37 @@ namespace xServer.Core.Cryptography
{
using (var ms = new MemoryStream(input))
{
using (var aesProvider = new AesCryptoServiceProvider() { Key = _defaultKey })
using (var aesProvider = new AesCryptoServiceProvider())
{
byte[] iv = new byte[IVLENGTH];
ms.Read(iv, 0, IVLENGTH); // read first 16 bytes for IV, followed by encrypted message
aesProvider.KeySize = 128;
aesProvider.BlockSize = 128;
aesProvider.Mode = CipherMode.CBC;
aesProvider.Padding = PaddingMode.PKCS7;
aesProvider.Key = _defaultKey;
// read first 32 bytes for HMAC
using (var hmac = new HMACSHA256(_defaultAuthKey))
{
var hash = hmac.ComputeHash(ms.ToArray(), HmacSha256Length, ms.ToArray().Length - HmacSha256Length);
byte[] receivedHash = new byte[HmacSha256Length];
ms.Read(receivedHash, 0, receivedHash.Length);
for (int i = 0; i < hash.Length; i++)
{
if (receivedHash[i] != hash[i])
{
return data;
}
}
}
byte[] iv = new byte[IvLength];
ms.Read(iv, 0, IvLength); // read next 16 bytes for IV, followed by ciphertext
aesProvider.IV = iv;
using (var cs = new CryptoStream(ms, aesProvider.CreateDecryptor(), CryptoStreamMode.Read))
{
byte[] temp = new byte[ms.Length - IVLENGTH + 1];
byte[] temp = new byte[ms.Length - IvLength + 1];
data = new byte[cs.Read(temp, 0, temp.Length)];
Buffer.BlockCopy(temp, 0, data, 0, data.Length);
}