Johanna
Reputation: 73
AES decryption/ encryption implementation in C# - not using libraries
I'm trying to implement a AES system in C# to encrypt and decrypt messages using AES. The decrypted message of an encrypted message is different from the original text.
Where am I going wrong?
PS: I have included the state.cs class which contains the mixcolumns, subbytes and shiftrow methods as well as the inverse of these methods.
private byte[] readHexString(string s)
{
int size = s.Length / 2;
byte[] b = new byte[size];
if ((size != 16) && (size != 24) && (size != 32))
{
throw new Exception();
}
for (int i = 0; i < size; i++)
{
b[i] = Convert.ToByte(s.Substring(2 * i, 2), 16);
}
return (b);
}
private byte[] readAsciiString(string s)
{
byte[] b = new byte[s.Length];
b = System.Text.ASCIIEncoding.ASCII.GetBytes(s);
return (b);
}
private void btnTest_Click(object sender, EventArgs e)
{
byte[] inputKey = readHexString(tbKey.Text);
Key key = new Key(inputKey);
Console.Out.WriteLine("\nkey:\n" + key);
byte[] inputPlain = readAsciiString(tbPlain.Text);
State inputState = new State(inputPlain);
Console.Out.WriteLine("state:\n" + inputState.ToMatrixString());
//string outplain = ConvertHex(Encrypt(inputState, key));
string ciphertext = Encrypt(inputState, key);
tbCiphertext.Text = ciphertext;
byte[] inputPlain2 = readAsciiString(tbCiphertext.Text);
State inputState2 = new State(inputPlain2);
string plaintext = Decrypt(inputState2, key);
Console.Out.WriteLine(plaintext);
}
private string Encrypt(State _inputState, Key k)
{
//string ciphertext;
byte[] ciphertext;
State thisState = _inputState;
thisState = thisState.addRoundKey(k, 0);
Console.Out.WriteLine(thisState.ToString());
for (int i = 1; i < 10; i++)
{
thisState = thisState.subBytes();
thisState = thisState.shiftRows();
thisState = thisState.mixColumns();
thisState = thisState.addRoundKey(k, i);
Console.Out.WriteLine(thisState.ToString());
}
thisState = thisState.subBytes();
thisState = thisState.shiftRows();
thisState = thisState.addRoundKey(k, 10);
Console.Out.WriteLine(thisState.ToString());
ciphertext = readHexString(thisState.ToString());
string output = "";
for (int i = 0; i < ciphertext.Length; i++)
{
output += ciphertext[i];
}
return ConvertHex(output);
}
public string Decrypt(State state, Key k)
{
byte[] plainText;
State thisState = state.addRoundKey(k, 10);
thisState = thisState.shiftRowsInv();
thisState = thisState.subBytesInv();
for (int i = 9; i > 0; i--)
{
thisState = thisState.addRoundKey(k, i);
thisState = thisState.mixColumnsInv();
thisState = thisState.shiftRowsInv();
thisState = thisState.subBytesInv();
}
thisState = thisState.addRoundKey(k, 0);
plainText = readHexString(thisState.ToString());
string output = "";
for (int i = 0; i < plainText.Length; i++)
{
output += plainText[i];
}
Console.Out.WriteLine(ConvertHex(output));
return ConvertHex(output);
}
public string ConvertHex(String hexString)
{
StringBuilder sb = new StringBuilder();
for (int i = 0; i <= hexString.Length - 2; i += 2)
{
sb.Append(Convert.ToString(Convert.ToChar(Int32.Parse(hexString.Substring(i, 2), System.Globalization.NumberStyles.HexNumber))));
}
return sb.ToString();
}
}
}
namespace Aes
{
public class State
{
private const int nrofRow = 4;
private const int nrofCol = 4;
private byte[,] buf;
//multiplication tables taken from http://en.wikipedia.org/wiki/Rijndael_mix_columns
private static byte[] mul2 = {
0x00,0x02,0x04,0x06,0x08,0x0a,0x0c,0x0e,0x10,0x12,0x14,0x16,0x18,0x1a,0x1c,0x1e,
0x20,0x22,0x24,0x26,0x28,0x2a,0x2c,0x2e,0x30,0x32,0x34,0x36,0x38,0x3a,0x3c,0x3e,
0x40,0x42,0x44,0x46,0x48,0x4a,0x4c,0x4e,0x50,0x52,0x54,0x56,0x58,0x5a,0x5c,0x5e,
0x60,0x62,0x64,0x66,0x68,0x6a,0x6c,0x6e,0x70,0x72,0x74,0x76,0x78,0x7a,0x7c,0x7e,
0x80,0x82,0x84,0x86,0x88,0x8a,0x8c,0x8e,0x90,0x92,0x94,0x96,0x98,0x9a,0x9c,0x9e,
0xa0,0xa2,0xa4,0xa6,0xa8,0xaa,0xac,0xae,0xb0,0xb2,0xb4,0xb6,0xb8,0xba,0xbc,0xbe,
0xc0,0xc2,0xc4,0xc6,0xc8,0xca,0xcc,0xce,0xd0,0xd2,0xd4,0xd6,0xd8,0xda,0xdc,0xde,
0xe0,0xe2,0xe4,0xe6,0xe8,0xea,0xec,0xee,0xf0,0xf2,0xf4,0xf6,0xf8,0xfa,0xfc,0xfe,
0x1b,0x19,0x1f,0x1d,0x13,0x11,0x17,0x15,0x0b,0x09,0x0f,0x0d,0x03,0x01,0x07,0x05,
0x3b,0x39,0x3f,0x3d,0x33,0x31,0x37,0x35,0x2b,0x29,0x2f,0x2d,0x23,0x21,0x27,0x25,
0x5b,0x59,0x5f,0x5d,0x53,0x51,0x57,0x55,0x4b,0x49,0x4f,0x4d,0x43,0x41,0x47,0x45,
0x7b,0x79,0x7f,0x7d,0x73,0x71,0x77,0x75,0x6b,0x69,0x6f,0x6d,0x63,0x61,0x67,0x65,
0x9b,0x99,0x9f,0x9d,0x93,0x91,0x97,0x95,0x8b,0x89,0x8f,0x8d,0x83,0x81,0x87,0x85,
0xbb,0xb9,0xbf,0xbd,0xb3,0xb1,0xb7,0xb5,0xab,0xa9,0xaf,0xad,0xa3,0xa1,0xa7,0xa5,
0xdb,0xd9,0xdf,0xdd,0xd3,0xd1,0xd7,0xd5,0xcb,0xc9,0xcf,0xcd,0xc3,0xc1,0xc7,0xc5,
0xfb,0xf9,0xff,0xfd,0xf3,0xf1,0xf7,0xf5,0xeb,0xe9,0xef,0xed,0xe3,0xe1,0xe7,0xe5
};
private static byte[] mul3 = {
0x00,0x03,0x06,0x05,0x0c,0x0f,0x0a,0x09,0x18,0x1b,0x1e,0x1d,0x14,0x17,0x12,0x11,
0x30,0x33,0x36,0x35,0x3c,0x3f,0x3a,0x39,0x28,0x2b,0x2e,0x2d,0x24,0x27,0x22,0x21,
0x60,0x63,0x66,0x65,0x6c,0x6f,0x6a,0x69,0x78,0x7b,0x7e,0x7d,0x74,0x77,0x72,0x71,
0x50,0x53,0x56,0x55,0x5c,0x5f,0x5a,0x59,0x48,0x4b,0x4e,0x4d,0x44,0x47,0x42,0x41,
0xc0,0xc3,0xc6,0xc5,0xcc,0xcf,0xca,0xc9,0xd8,0xdb,0xde,0xdd,0xd4,0xd7,0xd2,0xd1,
0xf0,0xf3,0xf6,0xf5,0xfc,0xff,0xfa,0xf9,0xe8,0xeb,0xee,0xed,0xe4,0xe7,0xe2,0xe1,
0xa0,0xa3,0xa6,0xa5,0xac,0xaf,0xaa,0xa9,0xb8,0xbb,0xbe,0xbd,0xb4,0xb7,0xb2,0xb1,
0x90,0x93,0x96,0x95,0x9c,0x9f,0x9a,0x99,0x88,0x8b,0x8e,0x8d,0x84,0x87,0x82,0x81,
0x9b,0x98,0x9d,0x9e,0x97,0x94,0x91,0x92,0x83,0x80,0x85,0x86,0x8f,0x8c,0x89,0x8a,
0xab,0xa8,0xad,0xae,0xa7,0xa4,0xa1,0xa2,0xb3,0xb0,0xb5,0xb6,0xbf,0xbc,0xb9,0xba,
0xfb,0xf8,0xfd,0xfe,0xf7,0xf4,0xf1,0xf2,0xe3,0xe0,0xe5,0xe6,0xef,0xec,0xe9,0xea,
0xcb,0xc8,0xcd,0xce,0xc7,0xc4,0xc1,0xc2,0xd3,0xd0,0xd5,0xd6,0xdf,0xdc,0xd9,0xda,
0x5b,0x58,0x5d,0x5e,0x57,0x54,0x51,0x52,0x43,0x40,0x45,0x46,0x4f,0x4c,0x49,0x4a,
0x6b,0x68,0x6d,0x6e,0x67,0x64,0x61,0x62,0x73,0x70,0x75,0x76,0x7f,0x7c,0x79,0x7a,
0x3b,0x38,0x3d,0x3e,0x37,0x34,0x31,0x32,0x23,0x20,0x25,0x26,0x2f,0x2c,0x29,0x2a,
0x0b,0x08,0x0d,0x0e,0x07,0x04,0x01,0x02,0x13,0x10,0x15,0x16,0x1f,0x1c,0x19,0x1a
};
private static byte[] mul09 = {
0x00,0x09,0x12,0x1b,0x24,0x2d,0x36,0x3f,0x48,0x41,0x5a,0x53,0x6c,0x65,0x7e,0x77,
0x90,0x99,0x82,0x8b,0xb4,0xbd,0xa6,0xaf,0xd8,0xd1,0xca,0xc3,0xfc,0xf5,0xee,0xe7,
0x3b,0x32,0x29,0x20,0x1f,0x16,0x0d,0x04,0x73,0x7a,0x61,0x68,0x57,0x5e,0x45,0x4c,
0xab,0xa2,0xb9,0xb0,0x8f,0x86,0x9d,0x94,0xe3,0xea,0xf1,0xf8,0xc7,0xce,0xd5,0xdc,
0x76,0x7f,0x64,0x6d,0x52,0x5b,0x40,0x49,0x3e,0x37,0x2c,0x25,0x1a,0x13,0x08,0x01,
0xe6,0xef,0xf4,0xfd,0xc2,0xcb,0xd0,0xd9,0xae,0xa7,0xbc,0xb5,0x8a,0x83,0x98,0x91,
0x4d,0x44,0x5f,0x56,0x69,0x60,0x7b,0x72,0x05,0x0c,0x17,0x1e,0x21,0x28,0x33,0x3a,
0xdd,0xd4,0xcf,0xc6,0xf9,0xf0,0xeb,0xe2,0x95,0x9c,0x87,0x8e,0xb1,0xb8,0xa3,0xaa,
0xec,0xe5,0xfe,0xf7,0xc8,0xc1,0xda,0xd3,0xa4,0xad,0xb6,0xbf,0x80,0x89,0x92,0x9b,
0x7c,0x75,0x6e,0x67,0x58,0x51,0x4a,0x43,0x34,0x3d,0x26,0x2f,0x10,0x19,0x02,0x0b,
0xd7,0xde,0xc5,0xcc,0xf3,0xfa,0xe1,0xe8,0x9f,0x96,0x8d,0x84,0xbb,0xb2,0xa9,0xa0,
0x47,0x4e,0x55,0x5c,0x63,0x6a,0x71,0x78,0x0f,0x06,0x1d,0x14,0x2b,0x22,0x39,0x30,
0x9a,0x93,0x88,0x81,0xbe,0xb7,0xac,0xa5,0xd2,0xdb,0xc0,0xc9,0xf6,0xff,0xe4,0xed,
0x0a,0x03,0x18,0x11,0x2e,0x27,0x3c,0x35,0x42,0x4b,0x50,0x59,0x66,0x6f,0x74,0x7d,
0xa1,0xa8,0xb3,0xba,0x85,0x8c,0x97,0x9e,0xe9,0xe0,0xfb,0xf2,0xcd,0xc4,0xdf,0xd6,
0x31,0x38,0x23,0x2a,0x15,0x1c,0x07,0x0e,0x79,0x70,0x6b,0x62,0x5d,0x54,0x4f,0x46
};
private static byte[] mul11 = {
0x00,0x0b,0x16,0x1d,0x2c,0x27,0x3a,0x31,0x58,0x53,0x4e,0x45,0x74,0x7f,0x62,0x69,
0xb0,0xbb,0xa6,0xad,0x9c,0x97,0x8a,0x81,0xe8,0xe3,0xfe,0xf5,0xc4,0xcf,0xd2,0xd9,
0x7b,0x70,0x6d,0x66,0x57,0x5c,0x41,0x4a,0x23,0x28,0x35,0x3e,0x0f,0x04,0x19,0x12,
0xcb,0xc0,0xdd,0xd6,0xe7,0xec,0xf1,0xfa,0x93,0x98,0x85,0x8e,0xbf,0xb4,0xa9,0xa2,
0xf6,0xfd,0xe0,0xeb,0xda,0xd1,0xcc,0xc7,0xae,0xa5,0xb8,0xb3,0x82,0x89,0x94,0x9f,
0x46,0x4d,0x50,0x5b,0x6a,0x61,0x7c,0x77,0x1e,0x15,0x08,0x03,0x32,0x39,0x24,0x2f,
0x8d,0x86,0x9b,0x90,0xa1,0xaa,0xb7,0xbc,0xd5,0xde,0xc3,0xc8,0xf9,0xf2,0xef,0xe4,
0x3d,0x36,0x2b,0x20,0x11,0x1a,0x07,0x0c,0x65,0x6e,0x73,0x78,0x49,0x42,0x5f,0x54,
0xf7,0xfc,0xe1,0xea,0xdb,0xd0,0xcd,0xc6,0xaf,0xa4,0xb9,0xb2,0x83,0x88,0x95,0x9e,
0x47,0x4c,0x51,0x5a,0x6b,0x60,0x7d,0x76,0x1f,0x14,0x09,0x02,0x33,0x38,0x25,0x2e,
0x8c,0x87,0x9a,0x91,0xa0,0xab,0xb6,0xbd,0xd4,0xdf,0xc2,0xc9,0xf8,0xf3,0xee,0xe5,
0x3c,0x37,0x2a,0x21,0x10,0x1b,0x06,0x0d,0x64,0x6f,0x72,0x79,0x48,0x43,0x5e,0x55,
0x01,0x0a,0x17,0x1c,0x2d,0x26,0x3b,0x30,0x59,0x52,0x4f,0x44,0x75,0x7e,0x63,0x68,
0xb1,0xba,0xa7,0xac,0x9d,0x96,0x8b,0x80,0xe9,0xe2,0xff,0xf4,0xc5,0xce,0xd3,0xd8,
0x7a,0x71,0x6c,0x67,0x56,0x5d,0x40,0x4b,0x22,0x29,0x34,0x3f,0x0e,0x05,0x18,0x13,
0xca,0xc1,0xdc,0xd7,0xe6,0xed,0xf0,0xfb,0x92,0x99,0x84,0x8f,0xbe,0xb5,0xa8,0xa3
};
private static byte[] mul13 = {
0x00,0x0d,0x1a,0x17,0x34,0x39,0x2e,0x23,0x68,0x65,0x72,0x7f,0x5c,0x51,0x46,0x4b,
0xd0,0xdd,0xca,0xc7,0xe4,0xe9,0xfe,0xf3,0xb8,0xb5,0xa2,0xaf,0x8c,0x81,0x96,0x9b,
0xbb,0xb6,0xa1,0xac,0x8f,0x82,0x95,0x98,0xd3,0xde,0xc9,0xc4,0xe7,0xea,0xfd,0xf0,
0x6b,0x66,0x71,0x7c,0x5f,0x52,0x45,0x48,0x03,0x0e,0x19,0x14,0x37,0x3a,0x2d,0x20,
0x6d,0x60,0x77,0x7a,0x59,0x54,0x43,0x4e,0x05,0x08,0x1f,0x12,0x31,0x3c,0x2b,0x26,
0xbd,0xb0,0xa7,0xaa,0x89,0x84,0x93,0x9e,0xd5,0xd8,0xcf,0xc2,0xe1,0xec,0xfb,0xf6,
0xd6,0xdb,0xcc,0xc1,0xe2,0xef,0xf8,0xf5,0xbe,0xb3,0xa4,0xa9,0x8a,0x87,0x90,0x9d,
0x06,0x0b,0x1c,0x11,0x32,0x3f,0x28,0x25,0x6e,0x63,0x74,0x79,0x5a,0x57,0x40,0x4d,
0xda,0xd7,0xc0,0xcd,0xee,0xe3,0xf4,0xf9,0xb2,0xbf,0xa8,0xa5,0x86,0x8b,0x9c,0x91,
0x0a,0x07,0x10,0x1d,0x3e,0x33,0x24,0x29,0x62,0x6f,0x78,0x75,0x56,0x5b,0x4c,0x41,
0x61,0x6c,0x7b,0x76,0x55,0x58,0x4f,0x42,0x09,0x04,0x13,0x1e,0x3d,0x30,0x27,0x2a,
0xb1,0xbc,0xab,0xa6,0x85,0x88,0x9f,0x92,0xd9,0xd4,0xc3,0xce,0xed,0xe0,0xf7,0xfa,
0xb7,0xba,0xad,0xa0,0x83,0x8e,0x99,0x94,0xdf,0xd2,0xc5,0xc8,0xeb,0xe6,0xf1,0xfc,
0x67,0x6a,0x7d,0x70,0x53,0x5e,0x49,0x44,0x0f,0x02,0x15,0x18,0x3b,0x36,0x21,0x2c,
0x0c,0x01,0x16,0x1b,0x38,0x35,0x22,0x2f,0x64,0x69,0x7e,0x73,0x50,0x5d,0x4a,0x47,
0xdc,0xd1,0xc6,0xcb,0xe8,0xe5,0xf2,0xff,0xb4,0xb9,0xae,0xa3,0x80,0x8d,0x9a,0x97
};
private static byte[] mul14 = {
0x00,0x0e,0x1c,0x12,0x38,0x36,0x24,0x2a,0x70,0x7e,0x6c,0x62,0x48,0x46,0x54,0x5a,
0xe0,0xee,0xfc,0xf2,0xd8,0xd6,0xc4,0xca,0x90,0x9e,0x8c,0x82,0xa8,0xa6,0xb4,0xba,
0xdb,0xd5,0xc7,0xc9,0xe3,0xed,0xff,0xf1,0xab,0xa5,0xb7,0xb9,0x93,0x9d,0x8f,0x81,
0x3b,0x35,0x27,0x29,0x03,0x0d,0x1f,0x11,0x4b,0x45,0x57,0x59,0x73,0x7d,0x6f,0x61,
0xad,0xa3,0xb1,0xbf,0x95,0x9b,0x89,0x87,0xdd,0xd3,0xc1,0xcf,0xe5,0xeb,0xf9,0xf7,
0x4d,0x43,0x51,0x5f,0x75,0x7b,0x69,0x67,0x3d,0x33,0x21,0x2f,0x05,0x0b,0x19,0x17,
0x76,0x78,0x6a,0x64,0x4e,0x40,0x52,0x5c,0x06,0x08,0x1a,0x14,0x3e,0x30,0x22,0x2c,
0x96,0x98,0x8a,0x84,0xae,0xa0,0xb2,0xbc,0xe6,0xe8,0xfa,0xf4,0xde,0xd0,0xc2,0xcc,
0x41,0x4f,0x5d,0x53,0x79,0x77,0x65,0x6b,0x31,0x3f,0x2d,0x23,0x09,0x07,0x15,0x1b,
0xa1,0xaf,0xbd,0xb3,0x99,0x97,0x85,0x8b,0xd1,0xdf,0xcd,0xc3,0xe9,0xe7,0xf5,0xfb,
0x9a,0x94,0x86,0x88,0xa2,0xac,0xbe,0xb0,0xea,0xe4,0xf6,0xf8,0xd2,0xdc,0xce,0xc0,
0x7a,0x74,0x66,0x68,0x42,0x4c,0x5e,0x50,0x0a,0x04,0x16,0x18,0x32,0x3c,0x2e,0x20,
0xec,0xe2,0xf0,0xfe,0xd4,0xda,0xc8,0xc6,0x9c,0x92,0x80,0x8e,0xa4,0xaa,0xb8,0xb6,
0x0c,0x02,0x10,0x1e,0x34,0x3a,0x28,0x26,0x7c,0x72,0x60,0x6e,0x44,0x4a,0x58,0x56,
0x37,0x39,0x2b,0x25,0x0f,0x01,0x13,0x1d,0x47,0x49,0x5b,0x55,0x7f,0x71,0x63,0x6d,
0xd7,0xd9,0xcb,0xc5,0xef,0xe1,0xf3,0xfd,0xa7,0xa9,0xbb,0xb5,0x9f,0x91,0x83,0x8d
};
private State()
{
buf = new byte[nrofRow, nrofCol];
for (int i = 0; i < nrofRow; i++)
{
for (int j = 0; j < nrofCol; j++)
{
buf[i, j] = 0;
}
}
}
public State(byte[] b)
{
buf = new byte[nrofRow, nrofCol];
for (int i = 0; i < nrofRow; i++)
{
for (int j = 0; j < nrofCol; j++)
{
buf[i, j] = b[i + (nrofRow * j)];
}
}
}
public State subBytes()
{
State s = new State();
for (int i = 0; i < nrofRow; i++)
{
for (int j = 0; j < nrofCol; j++)
{
s.buf[i, j] = Sbox.sbox[buf[i, j]];
//Console.Out.WriteLine("state[" + i + "," + j + "]=" + buf[i, j] + "--->" + s.buf[i, j]);
}
}
return (s);
}
public State shiftRows()
{
State s = new State();
for (int i = 0; i < nrofRow; i++)
{
for (int j = 0; j < nrofCol; j++)
{
s.buf[i, j] = buf[i, (i + j) % 4];
//Console.Out.WriteLine("state[" + i + "," + j + "]=" + s.buf[i, j]);
}
}
return (s);
}
public State mixColumns()
{
State s = new State();
for (int c = 0; c < nrofCol; c++)
{
s.buf[0, c] = (byte)(mul2[buf[0, c]] ^ mul3[buf[1, c]] ^ buf[2, c] ^ buf[3, c]);
s.buf[1, c] = (byte)(buf[0, c] ^ mul2[buf[1, c]] ^ mul3[buf[2, c]] ^ buf[3, c]);
s.buf[2, c] = (byte)(buf[0, c] ^ buf[1, c] ^ mul2[buf[2, c]] ^ mul3[buf[3, c]]);
s.buf[3, c] = (byte)(mul3[buf[0, c]] ^ buf[1, c] ^ buf[2, c] ^ mul2[buf[3, c]]);
}
return (s);
}
public State subBytesInv()
{
// TODO
State s = new State();
for (int i = 0; i < nrofRow; i++)
{
for (int j = 0; j < nrofCol; j++)
{
s.buf[i, j] = Sbox.sboxInv[buf[i, j]];
//Console.Out.WriteLine("state[" + i + "," + j + "]=" + buf[i, j] + "--->" + s.buf[i, j]);
}
}
return (s);
}
public State shiftRowsInv()
{
State s = new State();
for (int i = 0; i < nrofRow; i++)
{
for (int j = 0; j < nrofCol; j++)
{
s.buf[i, j] = buf[i, (j - i + 4) % 4];
// Console.Out.WriteLine("state[" + i + "," + j + "]=" + s.buf[i, j]);
}
}
return (s);
}
public State mixColumnsInv()
{
State s = new State();
for (int c = 0; c < nrofCol; c++)
{
s.buf[0, c] = (byte)(mul14[buf[0, c]] ^ mul11[buf[1, c]] ^ mul13[buf[2, c]] ^ mul09[buf[3, c]]);
s.buf[1, c] = (byte)(mul09[buf[0, c]] ^ mul14[buf[1, c]] ^ mul11[buf[2, c]] ^ mul13[buf[3, c]]);
s.buf[2, c] = (byte)(mul13[buf[0, c]] ^ mul09[buf[1, c]] ^ mul14[buf[2, c]] ^ mul11[buf[3, c]]);
s.buf[3, c] = (byte)(mul11[buf[0, c]] ^ mul13[buf[1, c]] ^ mul09[buf[2, c]] ^ mul14[buf[3, c]]);
}
return (s);
}
public State addRoundKey(Key key, int round)
{
State s = new State();
for (int c = 0; c < nrofCol; c++)
{
for (int r = 0; r < nrofRow; r++)
{
s.buf[r, c] = (byte)(buf[r, c] ^ key.w[r, c + 4 * round]);
//Console.Out.WriteLine("state[" + r + "," + c + "]=" + buf[r, c] + " XOR " + key.w[r, c + 4 * round] + " = " + s.buf[r, c]);
}
}
return (s);
}
public string ToMatrixString()
{
string s = "";
for (int i = 0; i < buf.GetLength(0); i++)
{
for (int j = 0; j < buf.GetLength(1); j++)
{
s += buf[i, j].ToString("X2") + " ";
}
s += "\n";
}
return (s);
}
public override string ToString()
{
string s = "";
for (int i = 0; i < buf.GetLength(1); i++)
{
for (int j = 0; j < buf.GetLength(0); j++)
{
s += buf[j, i].ToString("X2") + "";
}
}`enter code here`
return (s);
}
}
}
Upvotes: 0
Views: 3494
Answers (1)
Ian
Reputation: 30823
It is rather hard to check what is the mistake in your code, especially when some of your methods (especially in your State) are not available to check.
Here I can provide the AES128.cs code which I wrote myself and confirmed to be working. You can take a look and compare, especially on the intermediate methods like mixColumn, shiftRow, and sBox. People often got wrong there - including me as I coded.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace Cryptography {
public class AES128 {
public const int BLOCK_SIZE = (128 / 8);
public const int KEY_SIZE = (128 / 8);
public const int ROUND_NO = 10;
// forward sbox
private readonly byte[] sBox = new byte[256] {
//0 1 2 3 4 5 6 7 8 9 A B C D E F
0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76, //0
0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0, //1
0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15, //2
0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75, //3
0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84, //4
0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf, //5
0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8, //6
0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2, //7
0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73, //8
0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb, //9
0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79, //A
0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08, //B
0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a, //C
0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e, //D
0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf, //E
0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16 }; //F
private readonly byte[] inverseSBox = new byte[256] {
//0 1 2 3 4 5 6 7 8 9 A B C D E F
0x52, 0x09, 0x6A, 0xD5, 0x30, 0x36, 0xA5, 0x38, 0xBF, 0x40, 0xA3, 0x9E, 0x81, 0xF3, 0xD7, 0xFB, //0
0x7C, 0xE3, 0x39, 0x82, 0x9B, 0x2F, 0xFF, 0x87, 0x34, 0x8E, 0x43, 0x44, 0xC4, 0xDE, 0xE9, 0xCB, //1
0x54, 0x7B, 0x94, 0x32, 0xA6, 0xC2, 0x23, 0x3D, 0xEE, 0x4C, 0x95, 0x0B, 0x42, 0xFA, 0xC3, 0x4E, //2
0x08, 0x2E, 0xA1, 0x66, 0x28, 0xD9, 0x24, 0xB2, 0x76, 0x5B, 0xA2, 0x49, 0x6D, 0x8B, 0xD1, 0x25, //3
0x72, 0xF8, 0xF6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xD4, 0xA4, 0x5C, 0xCC, 0x5D, 0x65, 0xB6, 0x92, //4
0x6C, 0x70, 0x48, 0x50, 0xFD, 0xED, 0xB9, 0xDA, 0x5E, 0x15, 0x46, 0x57, 0xA7, 0x8D, 0x9D, 0x84, //5
0x90, 0xD8, 0xAB, 0x00, 0x8C, 0xBC, 0xD3, 0x0A, 0xF7, 0xE4, 0x58, 0x05, 0xB8, 0xB3, 0x45, 0x06, //6
0xD0, 0x2C, 0x1E, 0x8F, 0xCA, 0x3F, 0x0F, 0x02, 0xC1, 0xAF, 0xBD, 0x03, 0x01, 0x13, 0x8A, 0x6B, //7
0x3A, 0x91, 0x11, 0x41, 0x4F, 0x67, 0xDC, 0xEA, 0x97, 0xF2, 0xCF, 0xCE, 0xF0, 0xB4, 0xE6, 0x73, //8
0x96, 0xAC, 0x74, 0x22, 0xE7, 0xAD, 0x35, 0x85, 0xE2, 0xF9, 0x37, 0xE8, 0x1C, 0x75, 0xDF, 0x6E, //9
0x47, 0xF1, 0x1A, 0x71, 0x1D, 0x29, 0xC5, 0x89, 0x6F, 0xB7, 0x62, 0x0E, 0xAA, 0x18, 0xBE, 0x1B, //A
0xFC, 0x56, 0x3E, 0x4B, 0xC6, 0xD2, 0x79, 0x20, 0x9A, 0xDB, 0xC0, 0xFE, 0x78, 0xCD, 0x5A, 0xF4, //B
0x1F, 0xDD, 0xA8, 0x33, 0x88, 0x07, 0xC7, 0x31, 0xB1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xEC, 0x5F, //C
0x60, 0x51, 0x7F, 0xA9, 0x19, 0xB5, 0x4A, 0x0D, 0x2D, 0xE5, 0x7A, 0x9F, 0x93, 0xC9, 0x9C, 0xEF, //D
0xA0, 0xE0, 0x3B, 0x4D, 0xAE, 0x2A, 0xF5, 0xB0, 0xC8, 0xEB, 0xBB, 0x3C, 0x83, 0x53, 0x99, 0x61, //E
0x17, 0x2B, 0x04, 0x7E, 0xBA, 0x77, 0xD6, 0x26, 0xE1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0C, 0x7D }; //F
// round coefficients
private readonly byte[] roundCoefficient = new byte[ROUND_NO] {
0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36 }; //Round coefficient is 10, the number of key is 11
// keys
private byte[] key = new byte[KEY_SIZE] { 0x09, 0x15, 0x00, 0x97, 0x00, 0x12, 0x10, 0x13, 0x03, 0x02, 0x19, 0x02, 0x05, 0x00, 0x29, 0x80 };
private byte[][] subkeys = new byte[ROUND_NO + 1][]; //each subkey is 16-bytes length
public byte[] Key {
get { return key; }
set { //When key is set, subkeys are automatically generated
if (value == null || value.Length != KEY_SIZE)
return;
key = value;
Array.Copy(key, subkeys[0], KEY_SIZE);
for (int i = 0; i < ROUND_NO; ++i) {
Array.Copy(subkeys[i], subkeys[i + 1], KEY_SIZE);
keyTransform(subkeys[i + 1], i);
}
}
}
public byte[][] Subkeys { get { return subkeys; } }
public AES128(byte[] key = null) {
for (int i = 0; i < ROUND_NO + 1; ++i)
subkeys[i] = new byte[KEY_SIZE]; //All the necessary array size for this subkey is made at the beginning
Key = key != null && key.Length == KEY_SIZE ? key : this.key; //key / default key
}
private void keywordTransform (ref byte[] keyword, int roundno) { //round no starts from 0, ends at 9
if (roundno < 0 || roundno > ROUND_NO - 1)
return;
byte buf = keyword[0];
keyword[0] = (byte)(sBox[keyword[1]] ^ roundCoefficient[roundno]);
keyword[1] = sBox[keyword[2]];
keyword[2] = sBox[keyword[3]];
keyword[3] = sBox[buf];
}
private void keyTransform(byte[] key, int roundno) {
byte[] keyword = new byte[4];
Array.Copy(key, 12, keyword, 0, 4);
keywordTransform(ref keyword, roundno);
for (int k = 0; k < 4; ++k)
key[k] ^= keyword[k];
for (int i = 0; i < KEY_SIZE - 4; ++i)
key[i + 4] ^= key[i];
}
public const byte BYTE_POLY_REDUCTION = 0x1b;
public const ushort POLY_REDUCTION = 0x11b;
private void shiftRows(ref byte[] text) {
byte buf;
//shift row 2 (1 -> 13, 5 -> 1, 9 -> 5, 13 -> 9)
buf = text[1];
text[1] = text[5];
text[5] = text[9];
text[9] = text[13];
text[13] = buf;
//shift row 3 (2 -> 10, 6 -> 14, 10 -> 2, 14 -> 6)
buf = text[2];
text[2] = text[10];
text[10] = buf;
buf = text[6];
text[6] = text[14];
text[14] = buf;
//shift row 4 (3 -> 7, 7 -> 11, 11 -> 15, 15 -> 3)
buf = text[15];
text[15] = text[11];
text[11] = text[7];
text[7] = text[3];
text[3] = buf;
}
private void inverseShiftRows(ref byte[] text) {
byte buf;
//inverse shift row 2 (1 -> 5, 5 -> 9, 9 -> 13, 13 -> 1)
buf = text[1];
text[1] = text[13];
text[13] = text[9];
text[9] = text[5];
text[5] = buf;
//inverse shift row 3 (2 -> 10, 6 -> 14, 10 -> 2, 14 -> 6)
buf = text[2];
text[2] = text[10];
text[10] = buf;
buf = text[6];
text[6] = text[14];
text[14] = buf;
//inverse shift row 4 (3 -> 15, 7 -> 3, 11 -> 7, 15 -> 11)
buf = text[15];
text[15] = text[3];
text[3] = text[7];
text[7] = text[11];
text[11] = buf;
}
private byte galoisMult2(byte val, byte polyRed = BYTE_POLY_REDUCTION) { //used for GaloisMult with 2
return val >= 128 ? (byte)((val << 1) ^ polyRed) : (byte)(val << 1);
}
private byte[] quickXORTable = new byte[8] { 0x00, 0x1b, 0x36, 0x2d, 0x6c, 0x77, 0x5a, 0x41 };
private byte galoisDefaultMult(byte val, byte mult) {
int buf = val << 3;
if (mult != 0x0E)
buf ^= val;
if (mult > 0x0C)
buf ^= val << 2;
if ((mult & 0x02) > 0)
buf ^= val << 1;
byte xorval = quickXORTable[buf >> 8];
return xorval == 0 ? (byte)buf : (byte)(buf ^ xorval);
}
private void mixColumn(ref byte[] text) {
byte[] temp = new byte[4];
int p;
for (int i = 0; i < 4; ++i) {
p = i * 4;
temp[0] = (byte)(galoisMult2(text[p]) ^ (galoisMult2(text[p + 1]) ^ text[p + 1]) ^ text[p + 2] ^ text[p + 3]);
temp[1] = (byte)(galoisMult2(text[p + 1]) ^ (galoisMult2(text[p + 2]) ^ text[p + 2]) ^ text[p + 3] ^ text[p]);
temp[2] = (byte)(galoisMult2(text[p + 2]) ^ (galoisMult2(text[p + 3]) ^ text[p + 3]) ^ text[p] ^ text[p + 1]);
temp[3] = (byte)(galoisMult2(text[p + 3]) ^ (galoisMult2(text[p]) ^ text[p]) ^ text[p + 1] ^ text[p + 2]);
Array.Copy(temp, 0, text, p, 4);
}
}
private byte[] inverseMixColumnMatrixElementTable = new byte[] { 0x0B, 0x0D, 0x09, 0x0E, 0x0B, 0x0D, 0x09 };
private void inverseMixColumn(ref byte[] text) {
byte[] temp = new byte[4];
int p, p2;
for (int i = 0; i < 4; ++i) {
p = i * 4;
for (int j = 0; j < 4; ++j) {
p2 = 3 - j;
temp[j] = (byte)(galoisDefaultMult(text[p], inverseMixColumnMatrixElementTable[p2]) ^ galoisDefaultMult(text[p + 1], inverseMixColumnMatrixElementTable[p2 + 1])
^ galoisDefaultMult(text[p + 2], inverseMixColumnMatrixElementTable[p2 + 2]) ^ galoisDefaultMult(text[p + 3], inverseMixColumnMatrixElementTable[p2 + 3]));
}
Array.Copy(temp, 0, text, p, 4);
}
}
private void encryptBlock(byte[] plaintext, ref byte[] ciphertext) { //since this is private function, no "input protection" is needed.
plaintext.CopyTo(ciphertext, 0);
for (int j = 0; j < BLOCK_SIZE; ++j)
ciphertext[j] ^= Subkeys[0][j];
for (int r = 0; r < ROUND_NO; ++r) {
for (int i = 0; i < BLOCK_SIZE; ++i)
ciphertext[i] = sBox[ciphertext[i]];
shiftRows(ref ciphertext);
if (r < ROUND_NO - 1)
mixColumn(ref ciphertext);
for (int j = 0; j < AES128.BLOCK_SIZE; ++j)
ciphertext[j] ^= Subkeys[r + 1][j];
}
}
private void decryptBlock(byte[] ciphertext, ref byte[] plaintext) { //since this is private function, no "input protection" is needed.
ciphertext.CopyTo(plaintext, 0);
for (int r = 0; r < ROUND_NO; ++r) {
for (int j = 0; j < BLOCK_SIZE; ++j)
plaintext[j] ^= Subkeys[ROUND_NO - r][j];
if (r > 0)
inverseMixColumn(ref plaintext);
inverseShiftRows(ref plaintext);
for (int i = 0; i < BLOCK_SIZE; ++i)
plaintext[i] = inverseSBox[plaintext[i]];
}
for (int j = 0; j < BLOCK_SIZE; ++j)
plaintext[j] ^= Subkeys[0][j];
}
public bool Encrypt(byte[] plaintext, ref byte[] ciphertext) {
if (plaintext == null || ciphertext == null || ciphertext.Length < plaintext.Length) //invalid input(s)
return false;
int extrabytes = plaintext.Length % BLOCK_SIZE;
int pblock = plaintext.Length / BLOCK_SIZE + (extrabytes > 0 ? 1 : 0);
int cblock = ciphertext.Length / BLOCK_SIZE;
if (cblock < pblock) //invalid size
return false;
pblock = plaintext.Length / BLOCK_SIZE;
byte[] text = new byte[BLOCK_SIZE];
int p;
for (int k = 0; k < pblock; ++k) { //Encrypt all possible blocks
p = k * BLOCK_SIZE;
Array.Copy(plaintext, p, text, 0, BLOCK_SIZE);
encryptBlock(text, ref text);
Array.Copy(text, 0, ciphertext, p, BLOCK_SIZE);
}
if (extrabytes > 0) { //encrypt the left over
p = pblock * BLOCK_SIZE;
Array.Copy(plaintext, p, text, 0, extrabytes);
for (int i = extrabytes; i < BLOCK_SIZE; ++i) //TODO not sure if there is any faster way in C#
text[i] = 0;
encryptBlock(text, ref text);
Array.Copy(text, 0, ciphertext, p, BLOCK_SIZE);
}
return true;
}
public bool Decrypt(byte[] ciphertext, ref byte[] plaintext) { //can only recover up to valid multiplication of 16, extra bytes are not decrypted
if (plaintext == null || ciphertext == null) //invalid input(s)
return false;
int cblock = ciphertext.Length / BLOCK_SIZE;
int pblock = plaintext.Length / BLOCK_SIZE;
if (pblock < cblock)
return false; //invalid size
byte[] text = new byte[BLOCK_SIZE];
int p;
for (int k = 0; k < cblock; ++k) {
p = k * BLOCK_SIZE;
Array.Copy(ciphertext, p, text, 0, BLOCK_SIZE);
decryptBlock(text, ref text);
Array.Copy(text, 0, plaintext, p, BLOCK_SIZE);
} //extra bytes are not taken cared of...
return true;
}
}
}
Note: the code is meant for 128-bit key
Upvotes: 3