/// <summary>
/// Decrypt a WEP-encrypted packet
/// </summary>
/// <param name="encryptedPacket">WEP encrypted packet</param>
/// <param name="key">Decryption key</param>
/// <param name="decrypted">Decrypted packet</param>
/// <returns>True if successful, false if not</returns>
public static bool TryDecryptWEP(IEEE802_11 encryptedPacket, byte[] key, out IPacket decrypted)
{
if (key.Length != 5 && key.Length != 13 && key.Length != 16 && key.Length != 29 && key.Length != 61)
{
//throw new ArgumentException("Invalid WEP key length. [5,13,16,29,61]");
decrypted = null;
return false;
}
if (encryptedPacket.FrameType != (int)FrameTypes.Data || !encryptedPacket.IsWep)
{
decrypted = null;
return false;
}
var keyWithIV = new byte[key.Length + 3];
Array.Copy(encryptedPacket.CCMP_WEP_Data, keyWithIV, 3);
Array.Copy(key, 0, keyWithIV, 3, key.Length);
var rc4 = new RC4(keyWithIV);
var encryptedPayload =
encryptedPacket.Payload.ToArray()
.Concat(BitConverter.GetBytes(ByteOrder.NetworkToHostOrder(encryptedPacket.WEP_ICV)))
.ToArray();
var dec = new byte[encryptedPayload.Length];
rc4.decrypt(encryptedPayload, encryptedPayload.Length, dec);
var expectedCRC = BitConverter.ToUInt32(dec, dec.Length - 4);
dec = dec.Take(dec.Length - 4).ToArray();
if (Crc32Algorithm.Compute(dec) == expectedCRC)
{
var decryptedBytes =
encryptedPacket.ToArray().Take(24 + (encryptedPacket.QosControl?.Length ?? 0)).Concat(dec).ToArray();
decryptedBytes[1] &= 191; //Everything except protected
return IEEE802_11Factory.Instance.TryParse(decryptedBytes, out decrypted);
}
decrypted = null;
return false;
}
/// <summary>
/// Decrypt a packet encrypted with CCMP
/// </summary>
/// <param name="encryptedPacket">The encrypted packet</param>
/// <param name="temporalKey">The temporal key</param>
/// <param name="headerMode">Mode in which headers should be handled</param>
/// <param name="decrypted">Decrypted packet</param>
/// <returns>True if successful, false if not</returns>
/// <remarks>Ported from airdecap-ng</remarks>
public static bool TryDecryptCCMP(
IEEE802_11 encryptedPacket,
byte[] temporalKey,
DecryptionHeaderMode headerMode,
out IPacket decrypted)
{
if (temporalKey.Length != 16)
{
// throw new ArgumentException("temporalKey must be 16 bytes");
decrypted = null;
return false;
}
var decryptedBytes = encryptedPacket.ToArray();
int z, data_len, blocks, last, offset;
bool is_a4, is_qos;
var B0 = new byte[16];
var B = new byte[16];
var MIC = new byte[16];
var PacketNumber = new byte[6];
var AdditionalAuthData = new byte[32];
is_a4 = (decryptedBytes[1] & 3) == 3;
is_qos = (decryptedBytes[0] & 0x8C) == 0x88;
z = 24 + 6 * (is_a4 ? 1 : 0);
z += 2 * (is_qos ? 1 : 0);
PacketNumber[0] = decryptedBytes[z + 7];
PacketNumber[1] = decryptedBytes[z + 6];
PacketNumber[2] = decryptedBytes[z + 5];
PacketNumber[3] = decryptedBytes[z + 4];
PacketNumber[4] = decryptedBytes[z + 1];
PacketNumber[5] = decryptedBytes[z + 0];
data_len = decryptedBytes.Length - z - 8 - 8;
B0[0] = 0x59;
B0[1] = 0;
Array.Copy(decryptedBytes, 10, B0, 2, 6);
Array.Copy(PacketNumber, 0, B0, 8, 6);
B0[14] = (byte)((data_len >> 8) & 0xFF);
B0[15] = (byte)(data_len & 0xFF);
AdditionalAuthData[2] = (byte)(decryptedBytes[0] & 0x8F);
AdditionalAuthData[3] = (byte)(decryptedBytes[1] & 0xC7);
Array.Copy(decryptedBytes, 4, AdditionalAuthData, 4, 3 * 6);
AdditionalAuthData[22] = (byte)(decryptedBytes[22] & 0x0F);
if (is_a4)
{
Array.Copy(decryptedBytes, 24, AdditionalAuthData, 24, 6);
if (is_qos)
{
AdditionalAuthData[30] = (byte)(decryptedBytes[z - 2] & 0x0F);
AdditionalAuthData[31] = 0;
B0[1] = AdditionalAuthData[30];
AdditionalAuthData[1] = 22 + 2 + 6;
}
else
{
AdditionalAuthData[30] = 0;
AdditionalAuthData[31] = 0;
B0[1] = 0;
AdditionalAuthData[1] = 22 + 6;
}
}
else
{
if (is_qos)
{
AdditionalAuthData[24] = (byte)(decryptedBytes[z - 2] & 0x0F);
AdditionalAuthData[25] = 0;
B0[1] = AdditionalAuthData[24];
AdditionalAuthData[1] = 22 + 2;
}
else
{
AdditionalAuthData[24] = 0;
AdditionalAuthData[25] = 0;
B0[1] = 0;
AdditionalAuthData[1] = 22;
}
}
using (var aesFactory = Aes.Create())
{
aesFactory.Mode = CipherMode.ECB;
aesFactory.Key = temporalKey;
var aes = aesFactory.CreateEncryptor();
aes.TransformBlock(B0, 0, B0.Length, MIC, 0);
CFunctions.XOR(MIC, 0, AdditionalAuthData, 16);
aes.TransformBlock(MIC, 0, MIC.Length, MIC, 0);
CFunctions.XOR(MIC, 0, AdditionalAuthData.Skip(16).ToArray(), 16);
aes.TransformBlock(MIC, 0, MIC.Length, MIC, 0);
B0[0] &= 0x07;
B0[14] = 0;
B0[15] = 0;
aes.TransformBlock(B0, 0, B0.Length, B, 0);
CFunctions.XOR(decryptedBytes, decryptedBytes.Length - 8, B, 8);
blocks = (data_len + 16 - 1) / 16;
last = data_len % 16;
offset = z + 8;
for (var i = 1; i <= blocks; i++)
{
var n = last > 0 && i == blocks ? last : 16;
B0[14] = (byte)((i >> 8) & 0xFF);
B0[15] = (byte)(i & 0xFF);
aes.TransformBlock(B0, 0, B0.Length, B, 0);
CFunctions.XOR(decryptedBytes, offset, B, n);
CFunctions.XOR(MIC, 0, decryptedBytes.Skip(offset).ToArray(), n);
aes.TransformBlock(MIC, 0, MIC.Length, MIC, 0);
offset += n;
}
}
switch (headerMode)
{
case DecryptionHeaderMode.Removed:
{
decryptedBytes[1] &= 191; // Remove the protected bit
var decryptedBytesList = decryptedBytes.ToList();
decryptedBytesList.RemoveRange(34 - 8, 8);
// Remove CCMP Parameters (otherwise, without the protected bit it will break the parsing)
IEEE802_11 decryptedWithHeader;
if (IEEE802_11Factory.Instance.TryParse(decryptedBytesList.ToArray(), out decryptedWithHeader))
{
decrypted = decryptedWithHeader.Payload; // Remove the altered 802.11 header
}
else
{
decrypted = null;
return false;
}
break;
}
case DecryptionHeaderMode.Modified:
{
decryptedBytes[1] &= 191; // Remove the protected bit
var decryptedBytesList = decryptedBytes.ToList();
decryptedBytesList.RemoveRange(34 - 8, 8);
// Remove CCMP Parameters (otherwise, without the protected bit it will break the parsing)
if (!IEEE802_11Factory.Instance.TryParse(decryptedBytesList.ToArray(), out decrypted))
{
return false;
}
break;
}
case DecryptionHeaderMode.Untouched:
if (!IEEE802_11Factory.Instance.TryParse(decryptedBytes.ToArray(), out decrypted))
{
return false;
}
break;
default:
decrypted = null;
return false;
}
return CFunctions.memcmp(decryptedBytes.Skip(offset).Take(8).ToArray(), MIC.Take(8).ToArray()) == 0;
}
