using System;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Crypto.Utilities;
namespace Org.BouncyCastle.Crypto.Engines{
/**
* an implementation of the AES (Rijndael), from FIPS-197.
* <p>
* For further details see: <a href="http://csrc.nist.gov/encryption/aes/">http://csrc.nist.gov/encryption/aes/</a>.
*
* This implementation is based on optimizations from Dr. Brian Gladman's paper and C code at
* <a href="http://fp.gladman.plus.com/cryptography_technology/rijndael/">http://fp.gladman.plus.com/cryptography_technology/rijndael/</a>
*
* There are three levels of tradeoff of speed vs memory
* Because java has no preprocessor, they are written as three separate classes from which to choose
*
* The fastest uses 8Kbytes of static tables to precompute round calculations, 4 256 word tables for encryption
* and 4 for decryption.
*
* The middle performance version uses only one 256 word table for each, for a total of 2Kbytes,
* adding 12 rotate operations per round to compute the values contained in the other tables from
* the contents of the first
*
* The slowest version uses no static tables at all and computes the values
* in each round.
* </p>
* <p>
* This file contains the slowest performance version with no static tables
* for round precomputation, but it has the smallest foot print.
* </p>
*/
public class AesLightEngine
: IBlockCipher
{
// The S box
private static readonly byte[] S =
{
99, 124, 119, 123, 242, 107, 111, 197,
48, 1, 103, 43, 254, 215, 171, 118,
202, 130, 201, 125, 250, 89, 71, 240,
173, 212, 162, 175, 156, 164, 114, 192,
183, 253, 147, 38, 54, 63, 247, 204,
52, 165, 229, 241, 113, 216, 49, 21,
4, 199, 35, 195, 24, 150, 5, 154,
7, 18, 128, 226, 235, 39, 178, 117,
9, 131, 44, 26, 27, 110, 90, 160,
82, 59, 214, 179, 41, 227, 47, 132,
83, 209, 0, 237, 32, 252, 177, 91,
106, 203, 190, 57, 74, 76, 88, 207,
208, 239, 170, 251, 67, 77, 51, 133,
69, 249, 2, 127, 80, 60, 159, 168,
81, 163, 64, 143, 146, 157, 56, 245,
188, 182, 218, 33, 16, 255, 243, 210,
205, 12, 19, 236, 95, 151, 68, 23,
196, 167, 126, 61, 100, 93, 25, 115,
96, 129, 79, 220, 34, 42, 144, 136,
70, 238, 184, 20, 222, 94, 11, 219,
224, 50, 58, 10, 73, 6, 36, 92,
194, 211, 172, 98, 145, 149, 228, 121,
231, 200, 55, 109, 141, 213, 78, 169,
108, 86, 244, 234, 101, 122, 174, 8,
186, 120, 37, 46, 28, 166, 180, 198,
232, 221, 116, 31, 75, 189, 139, 138,
112, 62, 181, 102, 72, 3, 246, 14,
97, 53, 87, 185, 134, 193, 29, 158,
225, 248, 152, 17, 105, 217, 142, 148,
155, 30, 135, 233, 206, 85, 40, 223,
140, 161, 137, 13, 191, 230, 66, 104,
65, 153, 45, 15, 176, 84, 187, 22,
};
// The inverse S-box
private static readonly byte[] Si =
{
82, 9, 106, 213, 48, 54, 165, 56,
191, 64, 163, 158, 129, 243, 215, 251,
124, 227, 57, 130, 155, 47, 255, 135,
52, 142, 67, 68, 196, 222, 233, 203,
84, 123, 148, 50, 166, 194, 35, 61,
238, 76, 149, 11, 66, 250, 195, 78,
8, 46, 161, 102, 40, 217, 36, 178,
118, 91, 162, 73, 109, 139, 209, 37,
114, 248, 246, 100, 134, 104, 152, 22,
212, 164, 92, 204, 93, 101, 182, 146,
108, 112, 72, 80, 253, 237, 185, 218,
94, 21, 70, 87, 167, 141, 157, 132,
144, 216, 171, 0, 140, 188, 211, 10,
247, 228, 88, 5, 184, 179, 69, 6,
208, 44, 30, 143, 202, 63, 15, 2,
193, 175, 189, 3, 1, 19, 138, 107,
58, 145, 17, 65, 79, 103, 220, 234,
151, 242, 207, 206, 240, 180, 230, 115,
150, 172, 116, 34, 231, 173, 53, 133,
226, 249, 55, 232, 28, 117, 223, 110,
71, 241, 26, 113, 29, 41, 197, 137,
111, 183, 98, 14, 170, 24, 190, 27,
252, 86, 62, 75, 198, 210, 121, 32,
154, 219, 192, 254, 120, 205, 90, 244,
31, 221, 168, 51, 136, 7, 199, 49,
177, 18, 16, 89, 39, 128, 236, 95,
96, 81, 127, 169, 25, 181, 74, 13,
45, 229, 122, 159, 147, 201, 156, 239,
160, 224, 59, 77, 174, 42, 245, 176,
200, 235, 187, 60, 131, 83, 153, 97,
23, 43, 4, 126, 186, 119, 214, 38,
225, 105, 20, 99, 85, 33, 12, 125,
};
// vector used in calculating key schedule (powers of x in GF(256))
private static readonly byte[] rcon =
{
0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a,
0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91
};
private uint Shift(
uint r,
int shift)
{
return (r >> shift) | (r << (32 - shift));
}
/* multiply four bytes in GF(2^8) by 'x' {02} in parallel */
private const uint m1 = 0x80808080;
private const uint m2 = 0x7f7f7f7f;
private const uint m3 = 0x0000001b;
private uint FFmulX(
uint x)
{
return ((x & m2) << 1) ^ (((x & m1) >> 7) * m3);
}
/*
The following defines provide alternative definitions of FFmulX that might
give improved performance if a fast 32-bit multiply is not available.
private int FFmulX(int x) { int u = x & m1; u |= (u >> 1); return ((x & m2) << 1) ^ ((u >>> 3) | (u >>> 6)); }
private static final int m4 = 0x1b1b1b1b;
private int FFmulX(int x) { int u = x & m1; return ((x & m2) << 1) ^ ((u - (u >>> 7)) & m4); }
*/
private uint Mcol(
uint x)
{
uint f2 = FFmulX(x);
return f2 ^ Shift(x ^ f2, 8) ^ Shift(x, 16) ^ Shift(x, 24);
}
private uint Inv_Mcol(
uint x)
{
uint f2 = FFmulX(x);
uint f4 = FFmulX(f2);
uint f8 = FFmulX(f4);
uint f9 = x ^ f8;
return f2 ^ f4 ^ f8 ^ Shift(f2 ^ f9, 8) ^ Shift(f4 ^ f9, 16) ^ Shift(f9, 24);
}
private uint SubWord(
uint x)
{
return (uint)S[x&255]
| (((uint)S[(x>>8)&255]) << 8)
| (((uint)S[(x>>16)&255]) << 16)
| (((uint)S[(x>>24)&255]) << 24);
}
/**
* Calculate the necessary round keys
* The number of calculations depends on key size and block size
* AES specified a fixed block size of 128 bits and key sizes 128/192/256 bits
* This code is written assuming those are the only possible values
*/
private uint[,] GenerateWorkingKey(
byte[] key,
bool forEncryption)
{
int KC = key.Length / 4; // key length in words
int t;
if ((KC != 4) && (KC != 6) && (KC != 8))
throw new ArgumentException("Key length not 128/192/256 bits.");
ROUNDS = KC + 6; // This is not always true for the generalized Rijndael that allows larger block sizes
uint[,] W = new uint[ROUNDS+1,4]; // 4 words in a block
//
// copy the key into the round key array
//
t = 0;
for (int i = 0; i < key.Length; t++)
{
W[t >> 2, t & 3] = Pack.LE_To_UInt32(key, i);
i+=4;
}
//
// while not enough round key material calculated
// calculate new values
//
int k = (ROUNDS + 1) << 2;
for (int i = KC; (i < k); i++)
{
uint temp = W[(i-1)>>2,(i-1)&3];
if ((i % KC) == 0)
{
temp = SubWord(Shift(temp, 8)) ^ rcon[(i / KC)-1];
}
else if ((KC > 6) && ((i % KC) == 4))
{
temp = SubWord(temp);
}
W[i>>2,i&3] = W[(i - KC)>>2,(i-KC)&3] ^ temp;
}
if (!forEncryption)
{
for (int j = 1; j < ROUNDS; j++)
{
for (int i = 0; i < 4; i++)
{
W[j,i] = Inv_Mcol(W[j,i]);
}
}
}
return W;
}
private int ROUNDS;
private uint[,] WorkingKey;
private uint C0, C1, C2, C3;
private bool forEncryption;
private const int BLOCK_SIZE = 16;
/**
* default constructor - 128 bit block size.
*/
public AesLightEngine()
{
}
/**
* initialise an AES cipher.
*
* @param forEncryption whether or not we are for encryption.
* @param parameters the parameters required to set up the cipher.
* @exception ArgumentException if the parameters argument is
* inappropriate.
*/
public void Init(
bool forEncryption,
ICipherParameters parameters)
{
if (!(parameters is KeyParameter))
throw new ArgumentException("invalid parameter passed to AES init - " + parameters.GetType().ToString());
WorkingKey = GenerateWorkingKey(((KeyParameter)parameters).GetKey(), forEncryption);
this.forEncryption = forEncryption;
}
public string AlgorithmName
{
get { return "AES"; }
}
public bool IsPartialBlockOkay
{
get { return false; }
}
public int GetBlockSize()
{
return BLOCK_SIZE;
}
public int ProcessBlock(
byte[] input,
int inOff,
byte[] output,
int outOff)
{
if (WorkingKey == null)
{
throw new InvalidOperationException("AES engine not initialised");
}
if ((inOff + (32 / 2)) > input.Length)
{
throw new DataLengthException("input buffer too short");
}
if ((outOff + (32 / 2)) > output.Length)
{
throw new DataLengthException("output buffer too short");
}
if (forEncryption)
{
UnPackBlock(input, inOff);
EncryptBlock(WorkingKey);
PackBlock(output, outOff);
}
else
{
UnPackBlock(input, inOff);
DecryptBlock(WorkingKey);
PackBlock(output, outOff);
}
return BLOCK_SIZE;
}
public void Reset()
{
}
private void UnPackBlock(
byte[] bytes,
int off)
{
C0 = Pack.LE_To_UInt32(bytes, off);
C1 = Pack.LE_To_UInt32(bytes, off + 4);
C2 = Pack.LE_To_UInt32(bytes, off + 8);
C3 = Pack.LE_To_UInt32(bytes, off + 12);
}
private void PackBlock(
byte[] bytes,
int off)
{
Pack.UInt32_To_LE(C0, bytes, off);
Pack.UInt32_To_LE(C1, bytes, off + 4);
Pack.UInt32_To_LE(C2, bytes, off + 8);
Pack.UInt32_To_LE(C3, bytes, off + 12);
}
private void EncryptBlock(
uint[,] KW)
{
int r;
uint r0, r1, r2, r3;
C0 ^= KW[0,0];
C1 ^= KW[0,1];
C2 ^= KW[0,2];
C3 ^= KW[0,3];
for (r = 1; r < ROUNDS - 1;)
{
r0 = Mcol((uint)S[C0&255] ^ (((uint)S[(C1>>8)&255])<<8) ^ (((uint)S[(C2>>16)&255])<<16) ^ (((uint)S[(C3>>24)&255])<<24)) ^ KW[r,0];
r1 = Mcol((uint)S[C1&255] ^ (((uint)S[(C2>>8)&255])<<8) ^ (((uint)S[(C3>>16)&255])<<16) ^ (((uint)S[(C0>>24)&255])<<24)) ^ KW[r,1];
r2 = Mcol((uint)S[C2&255] ^ (((uint)S[(C3>>8)&255])<<8) ^ (((uint)S[(C0>>16)&255])<<16) ^ (((uint)S[(C1>>24)&255])<<24)) ^ KW[r,2];
r3 = Mcol((uint)S[C3&255] ^ (((uint)S[(C0>>8)&255])<<8) ^ (((uint)S[(C1>>16)&255])<<16) ^ (((uint)S[(C2>>24)&255])<<24)) ^ KW[r++,3];
C0 = Mcol((uint)S[r0&255] ^ (((uint)S[(r1>>8)&255])<<8) ^ (((uint)S[(r2>>16)&255])<<16) ^ (((uint)S[(r3>>24)&255])<<24)) ^ KW[r,0];
C1 = Mcol((uint)S[r1&255] ^ (((uint)S[(r2>>8)&255])<<8) ^ (((uint)S[(r3>>16)&255])<<16) ^ (((uint)S[(r0>>24)&255])<<24)) ^ KW[r,1];
C2 = Mcol((uint)S[r2&255] ^ (((uint)S[(r3>>8)&255])<<8) ^ (((uint)S[(r0>>16)&255])<<16) ^ (((uint)S[(r1>>24)&255])<<24)) ^ KW[r,2];
C3 = Mcol((uint)S[r3&255] ^ (((uint)S[(r0>>8)&255])<<8) ^ (((uint)S[(r1>>16)&255])<<16) ^ (((uint)S[(r2>>24)&255])<<24)) ^ KW[r++,3];
}
r0 = Mcol((uint)S[C0&255] ^ (((uint)S[(C1>>8)&255])<<8) ^ (((uint)S[(C2>>16)&255])<<16) ^ (((uint)S[(C3>>24)&255])<<24)) ^ KW[r,0];
r1 = Mcol((uint)S[C1&255] ^ (((uint)S[(C2>>8)&255])<<8) ^ (((uint)S[(C3>>16)&255])<<16) ^ (((uint)S[(C0>>24)&255])<<24)) ^ KW[r,1];
r2 = Mcol((uint)S[C2&255] ^ (((uint)S[(C3>>8)&255])<<8) ^ (((uint)S[(C0>>16)&255])<<16) ^ (((uint)S[(C1>>24)&255])<<24)) ^ KW[r,2];
r3 = Mcol((uint)S[C3&255] ^ (((uint)S[(C0>>8)&255])<<8) ^ (((uint)S[(C1>>16)&255])<<16) ^ (((uint)S[(C2>>24)&255])<<24)) ^ KW[r++,3];
// the final round is a simple function of S
C0 = (uint)S[r0&255] ^ (((uint)S[(r1>>8)&255])<<8) ^ (((uint)S[(r2>>16)&255])<<16) ^ (((uint)S[(r3>>24)&255])<<24) ^ KW[r,0];
C1 = (uint)S[r1&255] ^ (((uint)S[(r2>>8)&255])<<8) ^ (((uint)S[(r3>>16)&255])<<16) ^ (((uint)S[(r0>>24)&255])<<24) ^ KW[r,1];
C2 = (uint)S[r2&255] ^ (((uint)S[(r3>>8)&255])<<8) ^ (((uint)S[(r0>>16)&255])<<16) ^ (((uint)S[(r1>>24)&255])<<24) ^ KW[r,2];
C3 = (uint)S[r3&255] ^ (((uint)S[(r0>>8)&255])<<8) ^ (((uint)S[(r1>>16)&255])<<16) ^ (((uint)S[(r2>>24)&255])<<24) ^ KW[r,3];
}
private void DecryptBlock(
uint[,] KW)
{
int r;
uint r0, r1, r2, r3;
C0 ^= KW[ROUNDS,0];
C1 ^= KW[ROUNDS,1];
C2 ^= KW[ROUNDS,2];
C3 ^= KW[ROUNDS,3];
for (r = ROUNDS-1; r>1;)
{
r0 = Inv_Mcol((uint)Si[C0&255] ^ (((uint)Si[(C3>>8)&255])<<8) ^ (((uint)Si[(C2>>16)&255])<<16) ^ ((uint)Si[(C1>>24)&255]<<24)) ^ KW[r,0];
r1 = Inv_Mcol((uint)Si[C1&255] ^ (((uint)Si[(C0>>8)&255])<<8) ^ (((uint)Si[(C3>>16)&255])<<16) ^ ((uint)Si[(C2>>24)&255]<<24)) ^ KW[r,1];
r2 = Inv_Mcol((uint)Si[C2&255] ^ (((uint)Si[(C1>>8)&255])<<8) ^ (((uint)Si[(C0>>16)&255])<<16) ^ ((uint)Si[(C3>>24)&255]<<24)) ^ KW[r,2];
r3 = Inv_Mcol((uint)Si[C3&255] ^ (((uint)Si[(C2>>8)&255])<<8) ^ (((uint)Si[(C1>>16)&255])<<16) ^ ((uint)Si[(C0>>24)&255]<<24)) ^ KW[r--,3];
C0 = Inv_Mcol((uint)Si[r0&255] ^ (((uint)Si[(r3>>8)&255])<<8) ^ (((uint)Si[(r2>>16)&255])<<16) ^ ((uint)Si[(r1>>24)&255]<<24)) ^ KW[r,0];
C1 = Inv_Mcol((uint)Si[r1&255] ^ (((uint)Si[(r0>>8)&255])<<8) ^ (((uint)Si[(r3>>16)&255])<<16) ^ ((uint)Si[(r2>>24)&255]<<24)) ^ KW[r,1];
C2 = Inv_Mcol((uint)Si[r2&255] ^ (((uint)Si[(r1>>8)&255])<<8) ^ (((uint)Si[(r0>>16)&255])<<16) ^ ((uint)Si[(r3>>24)&255]<<24)) ^ KW[r,2];
C3 = Inv_Mcol((uint)Si[r3&255] ^ (((uint)Si[(r2>>8)&255])<<8) ^ (((uint)Si[(r1>>16)&255])<<16) ^ ((uint)Si[(r0>>24)&255]<<24)) ^ KW[r--,3];
}
r0 = Inv_Mcol((uint)Si[C0&255] ^ (((uint)Si[(C3>>8)&255])<<8) ^ (((uint)Si[(C2>>16)&255])<<16) ^ ((uint)Si[(C1>>24)&255]<<24)) ^ KW[r,0];
r1 = Inv_Mcol((uint)Si[C1&255] ^ (((uint)Si[(C0>>8)&255])<<8) ^ (((uint)Si[(C3>>16)&255])<<16) ^ ((uint)Si[(C2>>24)&255]<<24)) ^ KW[r,1];
r2 = Inv_Mcol((uint)Si[C2&255] ^ (((uint)Si[(C1>>8)&255])<<8) ^ (((uint)Si[(C0>>16)&255])<<16) ^ ((uint)Si[(C3>>24)&255]<<24)) ^ KW[r,2];
r3 = Inv_Mcol((uint)Si[C3&255] ^ (((uint)Si[(C2>>8)&255])<<8) ^ (((uint)Si[(C1>>16)&255])<<16) ^ ((uint)Si[(C0>>24)&255]<<24)) ^ KW[r,3];
// the final round's table is a simple function of Si
C0 = (uint)Si[r0&255] ^ (((uint)Si[(r3>>8)&255])<<8) ^ (((uint)Si[(r2>>16)&255])<<16) ^ (((uint)Si[(r1>>24)&255])<<24) ^ KW[0,0];
C1 = (uint)Si[r1&255] ^ (((uint)Si[(r0>>8)&255])<<8) ^ (((uint)Si[(r3>>16)&255])<<16) ^ (((uint)Si[(r2>>24)&255])<<24) ^ KW[0,1];
C2 = (uint)Si[r2&255] ^ (((uint)Si[(r1>>8)&255])<<8) ^ (((uint)Si[(r0>>16)&255])<<16) ^ (((uint)Si[(r3>>24)&255])<<24) ^ KW[0,2];
C3 = (uint)Si[r3&255] ^ (((uint)Si[(r2>>8)&255])<<8) ^ (((uint)Si[(r1>>16)&255])<<16) ^ (((uint)Si[(r0>>24)&255])<<24) ^ KW[0,3];
}
}
}
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