using System;
//http://msdn.microsoft.com/msdnmag/issues/03/11/AES/print.asp
//http://msdn.microsoft.com/msdnmag/issues/03/11/AES/default.aspx
//(c) James McCaffrey - Please check file: EULA.DOC
//Article title: Keep Your Data Secure with the New Advanced Encryption Standard
namespace aes
{
public class Aes // Advanced Encryption Standard
{
public enum KeySize { Bits128, Bits192, Bits256 }; // key size, in bits, for construtor
private int Nb; // block size in 32-bit words. Always 4 for AES. (128 bits).
private int Nk; // key size in 32-bit words. 4, 6, 8. (128, 192, 256 bits).
private int Nr; // number of rounds. 10, 12, 14.
private byte[] key; // the seed key. size will be 4 * keySize from ctor.
private byte[,] Sbox; // Substitution box
private byte[,] iSbox; // inverse Substitution box
private byte[,] w; // key schedule array.
private byte[,] Rcon; // Round constants.
private byte[,] State; // State matrix
public Aes(KeySize keySize, byte[] keyBytes)
{
SetNbNkNr(keySize);
this.key = new byte[this.Nk * 4]; // 16, 24, 32 bytes
keyBytes.CopyTo(this.key, 0);
BuildSbox();
BuildInvSbox();
BuildRcon();
KeyExpansion(); // expand the seed key into a key schedule and store in w
} // Aes constructor
public void Cipher(byte[] input, byte[] output) // encipher 16-bit input
{
// state = input
this.State = new byte[4,Nb]; // always [4,4]
for (int i = 0; i < (4 * Nb); ++i)
{
this.State[i % 4, i / 4] = input[i];
}
AddRoundKey(0);
for (int round = 1; round <= (Nr - 1); ++round) // main round loop
{
SubBytes();
ShiftRows();
MixColumns();
AddRoundKey(round);
} // main round loop
SubBytes();
ShiftRows();
AddRoundKey(Nr);
// output = state
for (int i = 0; i < (4 * Nb); ++i)
{
output[i] = this.State[i % 4, i / 4];
}
} // Cipher()
public void InvCipher(byte[] input, byte[] output) // decipher 16-bit input
{
// state = input
this.State = new byte[4,Nb]; // always [4,4]
for (int i = 0; i < (4 * Nb); ++i)
{
this.State[i % 4, i / 4] = input[i];
}
AddRoundKey(Nr);
for (int round = Nr-1; round >= 1; --round) // main round loop
{
InvShiftRows();
InvSubBytes();
AddRoundKey(round);
InvMixColumns();
} // end main round loop for InvCipher
InvShiftRows();
InvSubBytes();
AddRoundKey(0);
// output = state
for (int i = 0; i < (4 * Nb); ++i)
{
output[i] = this.State[i % 4, i / 4];
}
} // InvCipher()
private void SetNbNkNr(KeySize keySize)
{
this.Nb = 4; // block size always = 4 words = 16 bytes = 128 bits for AES
if (keySize == KeySize.Bits128)
{
this.Nk = 4; // key size = 4 words = 16 bytes = 128 bits
this.Nr = 10; // rounds for algorithm = 10
}
else if (keySize == KeySize.Bits192)
{
this.Nk = 6; // 6 words = 24 bytes = 192 bits
this.Nr = 12;
}
else if (keySize == KeySize.Bits256)
{
this.Nk = 8; // 8 words = 32 bytes = 256 bits
this.Nr = 14;
}
} // SetNbNkNr()
private void BuildSbox()
{
this.Sbox = new byte[16,16] { // populate the Sbox matrix
/* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
/*0*/ {0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76},
/*1*/ {0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0},
/*2*/ {0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15},
/*3*/ {0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75},
/*4*/ {0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84},
/*5*/ {0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf},
/*6*/ {0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8},
/*7*/ {0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2},
/*8*/ {0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73},
/*9*/ {0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb},
/*a*/ {0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79},
/*b*/ {0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08},
/*c*/ {0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a},
/*d*/ {0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e},
/*e*/ {0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf},
/*f*/ {0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16} };
} // BuildSbox()
private void BuildInvSbox()
{
this.iSbox = new byte[16,16] { // populate the iSbox matrix
/* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
/*0*/ {0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb},
/*1*/ {0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb},
/*2*/ {0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e},
/*3*/ {0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25},
/*4*/ {0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92},
/*5*/ {0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84},
/*6*/ {0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06},
/*7*/ {0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b},
/*8*/ {0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73},
/*9*/ {0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e},
/*a*/ {0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b},
/*b*/ {0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4},
/*c*/ {0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f},
/*d*/ {0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef},
/*e*/ {0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61},
/*f*/ {0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d} };
} // BuildInvSbox()
private void BuildRcon()
{
this.Rcon = new byte[11,4] { {0x00, 0x00, 0x00, 0x00},
{0x01, 0x00, 0x00, 0x00},
{0x02, 0x00, 0x00, 0x00},
{0x04, 0x00, 0x00, 0x00},
{0x08, 0x00, 0x00, 0x00},
{0x10, 0x00, 0x00, 0x00},
{0x20, 0x00, 0x00, 0x00},
{0x40, 0x00, 0x00, 0x00},
{0x80, 0x00, 0x00, 0x00},
{0x1b, 0x00, 0x00, 0x00},
{0x36, 0x00, 0x00, 0x00} };
} // BuildRcon()
private void AddRoundKey(int round)
{
for (int r = 0; r < 4; ++r)
{
for (int c = 0; c < 4; ++c)
{
this.State[r,c] = (byte) ( (int)this.State[r,c] ^ (int)w[(round*4)+c,r] );
}
}
} // AddRoundKey()
private void SubBytes()
{
for (int r = 0; r < 4; ++r)
{
for (int c = 0; c < 4; ++c)
{
this.State[r,c] = this.Sbox[ (this.State[r,c] >> 4), (this.State[r,c] & 0x0f) ];
}
}
} // SubBytes
private void InvSubBytes()
{
for (int r = 0; r < 4; ++r)
{
for (int c = 0; c < 4; ++c)
{
this.State[r,c] = this.iSbox[ (this.State[r,c] >> 4), (this.State[r,c] & 0x0f) ];
}
}
} // InvSubBytes
private void ShiftRows()
{
byte[,] temp = new byte[4,4];
for (int r = 0; r < 4; ++r) // copy State into temp[]
{
for (int c = 0; c < 4; ++c)
{
temp[r,c] = this.State[r,c];
}
}
for (int r = 1; r < 4; ++r) // shift temp into State
{
for (int c = 0; c < 4; ++c)
{
this.State[r,c] = temp[ r, (c + r) % Nb ];
}
}
} // ShiftRows()
private void InvShiftRows()
{
byte[,] temp = new byte[4,4];
for (int r = 0; r < 4; ++r) // copy State into temp[]
{
for (int c = 0; c < 4; ++c)
{
temp[r,c] = this.State[r,c];
}
}
for (int r = 1; r < 4; ++r) // shift temp into State
{
for (int c = 0; c < 4; ++c)
{
this.State[r, (c + r) % Nb ] = temp[r,c];
}
}
} // InvShiftRows()
private void MixColumns()
{
byte[,] temp = new byte[4,4];
for (int r = 0; r < 4; ++r) // copy State into temp[]
{
for (int c = 0; c < 4; ++c)
{
temp[r,c] = this.State[r,c];
}
}
for (int c = 0; c < 4; ++c)
{
this.State[0,c] = (byte) ( (int)gfmultby02(temp[0,c]) ^ (int)gfmultby03(temp[1,c]) ^
(int)gfmultby01(temp[2,c]) ^ (int)gfmultby01(temp[3,c]) );
this.State[1,c] = (byte) ( (int)gfmultby01(temp[0,c]) ^ (int)gfmultby02(temp[1,c]) ^
(int)gfmultby03(temp[2,c]) ^ (int)gfmultby01(temp[3,c]) );
this.State[2,c] = (byte) ( (int)gfmultby01(temp[0,c]) ^ (int)gfmultby01(temp[1,c]) ^
(int)gfmultby02(temp[2,c]) ^ (int)gfmultby03(temp[3,c]) );
this.State[3,c] = (byte) ( (int)gfmultby03(temp[0,c]) ^ (int)gfmultby01(temp[1,c]) ^
(int)gfmultby01(temp[2,c]) ^ (int)gfmultby02(temp[3,c]) );
}
} // MixColumns
private void InvMixColumns()
{
byte[,] temp = new byte[4,4];
for (int r = 0; r < 4; ++r) // copy State into temp[]
{
for (int c = 0; c < 4; ++c)
{
temp[r,c] = this.State[r,c];
}
}
for (int c = 0; c < 4; ++c)
{
this.State[0,c] = (byte) ( (int)gfmultby0e(temp[0,c]) ^ (int)gfmultby0b(temp[1,c]) ^
(int)gfmultby0d(temp[2,c]) ^ (int)gfmultby09(temp[3,c]) );
this.State[1,c] = (byte) ( (int)gfmultby09(temp[0,c]) ^ (int)gfmultby0e(temp[1,c]) ^
(int)gfmultby0b(temp[2,c]) ^ (int)gfmultby0d(temp[3,c]) );
this.State[2,c] = (byte) ( (int)gfmultby0d(temp[0,c]) ^ (int)gfmultby09(temp[1,c]) ^
(int)gfmultby0e(temp[2,c]) ^ (int)gfmultby0b(temp[3,c]) );
this.State[3,c] = (byte) ( (int)gfmultby0b(temp[0,c]) ^ (int)gfmultby0d(temp[1,c]) ^
(int)gfmultby09(temp[2,c]) ^ (int)gfmultby0e(temp[3,c]) );
}
} // InvMixColumns
private static byte gfmultby01(byte b)
{
return b;
}
private static byte gfmultby02(byte b)
{
if (b < 0x80)
return (byte)(int)(b << 1);
else
return (byte)( (int)(b << 1) ^ (int)(0x1b) );
}
private static byte gfmultby03(byte b)
{
return (byte) ( (int)gfmultby02(b) ^ (int)b );
}
private static byte gfmultby09(byte b)
{
return (byte)( (int)gfmultby02(gfmultby02(gfmultby02(b))) ^
(int)b );
}
private static byte gfmultby0b(byte b)
{
return (byte)( (int)gfmultby02(gfmultby02(gfmultby02(b))) ^
(int)gfmultby02(b) ^
(int)b );
}
private static byte gfmultby0d(byte b)
{
return (byte)( (int)gfmultby02(gfmultby02(gfmultby02(b))) ^
(int)gfmultby02(gfmultby02(b)) ^
(int)(b) );
}
private static byte gfmultby0e(byte b)
{
return (byte)( (int)gfmultby02(gfmultby02(gfmultby02(b))) ^
(int)gfmultby02(gfmultby02(b)) ^
(int)gfmultby02(b) );
}
private void KeyExpansion()
{
this.w = new byte[Nb * (Nr+1), 4]; // 4 columns of bytes corresponds to a word
for (int row = 0; row < Nk; ++row)
{
this.w[row,0] = this.key[4*row];
this.w[row,1] = this.key[4*row+1];
this.w[row,2] = this.key[4*row+2];
this.w[row,3] = this.key[4*row+3];
}
byte[] temp = new byte[4];
for (int row = Nk; row < Nb * (Nr+1); ++row)
{
temp[0] = this.w[row-1,0]; temp[1] = this.w[row-1,1];
temp[2] = this.w[row-1,2]; temp[3] = this.w[row-1,3];
if (row % Nk == 0)
{
temp = SubWord(RotWord(temp));
temp[0] = (byte)( (int)temp[0] ^ (int)this.Rcon[row/Nk,0] );
temp[1] = (byte)( (int)temp[1] ^ (int)this.Rcon[row/Nk,1] );
temp[2] = (byte)( (int)temp[2] ^ (int)this.Rcon[row/Nk,2] );
temp[3] = (byte)( (int)temp[3] ^ (int)this.Rcon[row/Nk,3] );
}
else if ( Nk > 6 && (row % Nk == 4) )
{
temp = SubWord(temp);
}
// w[row] = w[row-Nk] xor temp
this.w[row,0] = (byte) ( (int)this.w[row-Nk,0] ^ (int)temp[0] );
this.w[row,1] = (byte) ( (int)this.w[row-Nk,1] ^ (int)temp[1] );
this.w[row,2] = (byte) ( (int)this.w[row-Nk,2] ^ (int)temp[2] );
this.w[row,3] = (byte) ( (int)this.w[row-Nk,3] ^ (int)temp[3] );
} // for loop
} // KeyExpansion()
private byte[] SubWord(byte[] word)
{
byte[] result = new byte[4];
result[0] = this.Sbox[ word[0] >> 4, word[0] & 0x0f ];
result[1] = this.Sbox[ word[1] >> 4, word[1] & 0x0f ];
result[2] = this.Sbox[ word[2] >> 4, word[2] & 0x0f ];
result[3] = this.Sbox[ word[3] >> 4, word[3] & 0x0f ];
return result;
}
private byte[] RotWord(byte[] word)
{
byte[] result = new byte[4];
result[0] = word[1];
result[1] = word[2];
result[2] = word[3];
result[3] = word[0];
return result;
}
/*
public void Dump()
{
Console.WriteLine("Nb = " + Nb + " Nk = " + Nk + " Nr = " + Nr);
Console.WriteLine("\nThe key is \n" + DumpKey() );
Console.WriteLine("\nThe Sbox is \n" + DumpTwoByTwo(Sbox));
Console.WriteLine("\nThe w array is \n" + DumpTwoByTwo(w));
Console.WriteLine("\nThe State array is \n" + DumpTwoByTwo(State));
}
public string DumpKey()
{
string s = "";
for (int i = 0; i < key.Length; ++i)
s += key[i].ToString("x2") + " ";
return s;
}
public string DumpTwoByTwo(byte[,] a)
{
string s ="";
for (int r = 0; r < a.GetLength(0); ++r)
{
s += "["+r+"]" + " ";
for (int c = 0; c < a.GetLength(1); ++c)
{
s += a[r,c].ToString("x2") + " " ;
}
s += "\n";
}
return s;
}
*/
} // class Aes
} // ns AesLib
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