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arduinolibs/libraries/Crypto/AESCommon.cpp
Rhys Weatherley 07a47cdcf1 ChaCha stream cipher
2015-01-02 08:51:46 +10:00

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/*
* Copyright (C) 2015 Southern Storm Software, Pty Ltd.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*/
#include "AES.h"
#include "Crypto.h"
/**
* \class AESCommon AES.h <AES.h>
* \brief Abstract base class for AES block ciphers.
*
* This class is abstract. The caller should instantiate AES128,
* AES192, or AES256 to create an AES block cipher with a specific
* key size.
*
* \note This AES implementation does not have constant cache behaviour due
* to the use of table lookups. It may not be safe to use this implementation
* in an environment where the attacker can observe the timing of encryption
* and decryption operations. Unless AES compatibility is required,
* it is recommended that the ChaCha stream cipher be used instead.
*
* Reference: http://en.wikipedia.org/wiki/Advanced_Encryption_Standard
*
* \sa ChaCha, AES128, AES192, AES256
*/
// AES S-box (http://en.wikipedia.org/wiki/Rijndael_S-box)
static uint8_t const sbox[256] = {
0x63, 0x7C, 0x77, 0x7B, 0xF2, 0x6B, 0x6F, 0xC5, // 0x00
0x30, 0x01, 0x67, 0x2B, 0xFE, 0xD7, 0xAB, 0x76,
0xCA, 0x82, 0xC9, 0x7D, 0xFA, 0x59, 0x47, 0xF0, // 0x10
0xAD, 0xD4, 0xA2, 0xAF, 0x9C, 0xA4, 0x72, 0xC0,
0xB7, 0xFD, 0x93, 0x26, 0x36, 0x3F, 0xF7, 0xCC, // 0x20
0x34, 0xA5, 0xE5, 0xF1, 0x71, 0xD8, 0x31, 0x15,
0x04, 0xC7, 0x23, 0xC3, 0x18, 0x96, 0x05, 0x9A, // 0x30
0x07, 0x12, 0x80, 0xE2, 0xEB, 0x27, 0xB2, 0x75,
0x09, 0x83, 0x2C, 0x1A, 0x1B, 0x6E, 0x5A, 0xA0, // 0x40
0x52, 0x3B, 0xD6, 0xB3, 0x29, 0xE3, 0x2F, 0x84,
0x53, 0xD1, 0x00, 0xED, 0x20, 0xFC, 0xB1, 0x5B, // 0x50
0x6A, 0xCB, 0xBE, 0x39, 0x4A, 0x4C, 0x58, 0xCF,
0xD0, 0xEF, 0xAA, 0xFB, 0x43, 0x4D, 0x33, 0x85, // 0x60
0x45, 0xF9, 0x02, 0x7F, 0x50, 0x3C, 0x9F, 0xA8,
0x51, 0xA3, 0x40, 0x8F, 0x92, 0x9D, 0x38, 0xF5, // 0x70
0xBC, 0xB6, 0xDA, 0x21, 0x10, 0xFF, 0xF3, 0xD2,
0xCD, 0x0C, 0x13, 0xEC, 0x5F, 0x97, 0x44, 0x17, // 0x80
0xC4, 0xA7, 0x7E, 0x3D, 0x64, 0x5D, 0x19, 0x73,
0x60, 0x81, 0x4F, 0xDC, 0x22, 0x2A, 0x90, 0x88, // 0x90
0x46, 0xEE, 0xB8, 0x14, 0xDE, 0x5E, 0x0B, 0xDB,
0xE0, 0x32, 0x3A, 0x0A, 0x49, 0x06, 0x24, 0x5C, // 0xA0
0xC2, 0xD3, 0xAC, 0x62, 0x91, 0x95, 0xE4, 0x79,
0xE7, 0xC8, 0x37, 0x6D, 0x8D, 0xD5, 0x4E, 0xA9, // 0xB0
0x6C, 0x56, 0xF4, 0xEA, 0x65, 0x7A, 0xAE, 0x08,
0xBA, 0x78, 0x25, 0x2E, 0x1C, 0xA6, 0xB4, 0xC6, // 0xC0
0xE8, 0xDD, 0x74, 0x1F, 0x4B, 0xBD, 0x8B, 0x8A,
0x70, 0x3E, 0xB5, 0x66, 0x48, 0x03, 0xF6, 0x0E, // 0xD0
0x61, 0x35, 0x57, 0xB9, 0x86, 0xC1, 0x1D, 0x9E,
0xE1, 0xF8, 0x98, 0x11, 0x69, 0xD9, 0x8E, 0x94, // 0xE0
0x9B, 0x1E, 0x87, 0xE9, 0xCE, 0x55, 0x28, 0xDF,
0x8C, 0xA1, 0x89, 0x0D, 0xBF, 0xE6, 0x42, 0x68, // 0xF0
0x41, 0x99, 0x2D, 0x0F, 0xB0, 0x54, 0xBB, 0x16
};
// AES inverse S-box (http://en.wikipedia.org/wiki/Rijndael_S-box)
static uint8_t const sbox_inverse[256] = {
0x52, 0x09, 0x6A, 0xD5, 0x30, 0x36, 0xA5, 0x38, // 0x00
0xBF, 0x40, 0xA3, 0x9E, 0x81, 0xF3, 0xD7, 0xFB,
0x7C, 0xE3, 0x39, 0x82, 0x9B, 0x2F, 0xFF, 0x87, // 0x10
0x34, 0x8E, 0x43, 0x44, 0xC4, 0xDE, 0xE9, 0xCB,
0x54, 0x7B, 0x94, 0x32, 0xA6, 0xC2, 0x23, 0x3D, // 0x20
0xEE, 0x4C, 0x95, 0x0B, 0x42, 0xFA, 0xC3, 0x4E,
0x08, 0x2E, 0xA1, 0x66, 0x28, 0xD9, 0x24, 0xB2, // 0x30
0x76, 0x5B, 0xA2, 0x49, 0x6D, 0x8B, 0xD1, 0x25,
0x72, 0xF8, 0xF6, 0x64, 0x86, 0x68, 0x98, 0x16, // 0x40
0xD4, 0xA4, 0x5C, 0xCC, 0x5D, 0x65, 0xB6, 0x92,
0x6C, 0x70, 0x48, 0x50, 0xFD, 0xED, 0xB9, 0xDA, // 0x50
0x5E, 0x15, 0x46, 0x57, 0xA7, 0x8D, 0x9D, 0x84,
0x90, 0xD8, 0xAB, 0x00, 0x8C, 0xBC, 0xD3, 0x0A, // 0x60
0xF7, 0xE4, 0x58, 0x05, 0xB8, 0xB3, 0x45, 0x06,
0xD0, 0x2C, 0x1E, 0x8F, 0xCA, 0x3F, 0x0F, 0x02, // 0x70
0xC1, 0xAF, 0xBD, 0x03, 0x01, 0x13, 0x8A, 0x6B,
0x3A, 0x91, 0x11, 0x41, 0x4F, 0x67, 0xDC, 0xEA, // 0x80
0x97, 0xF2, 0xCF, 0xCE, 0xF0, 0xB4, 0xE6, 0x73,
0x96, 0xAC, 0x74, 0x22, 0xE7, 0xAD, 0x35, 0x85, // 0x90
0xE2, 0xF9, 0x37, 0xE8, 0x1C, 0x75, 0xDF, 0x6E,
0x47, 0xF1, 0x1A, 0x71, 0x1D, 0x29, 0xC5, 0x89, // 0xA0
0x6F, 0xB7, 0x62, 0x0E, 0xAA, 0x18, 0xBE, 0x1B,
0xFC, 0x56, 0x3E, 0x4B, 0xC6, 0xD2, 0x79, 0x20, // 0xB0
0x9A, 0xDB, 0xC0, 0xFE, 0x78, 0xCD, 0x5A, 0xF4,
0x1F, 0xDD, 0xA8, 0x33, 0x88, 0x07, 0xC7, 0x31, // 0xC0
0xB1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xEC, 0x5F,
0x60, 0x51, 0x7F, 0xA9, 0x19, 0xB5, 0x4A, 0x0D, // 0xD0
0x2D, 0xE5, 0x7A, 0x9F, 0x93, 0xC9, 0x9C, 0xEF,
0xA0, 0xE0, 0x3B, 0x4D, 0xAE, 0x2A, 0xF5, 0xB0, // 0xE0
0xC8, 0xEB, 0xBB, 0x3C, 0x83, 0x53, 0x99, 0x61,
0x17, 0x2B, 0x04, 0x7E, 0xBA, 0x77, 0xD6, 0x26, // 0xF0
0xE1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0C, 0x7D
};
/**
* \brief Constructs an AES block cipher object.
*/
AESCommon::AESCommon()
: rounds(0), schedule(0)
{
}
/**
* \brief Destroys this AES block cipher object after clearing
* sensitive information.
*/
AESCommon::~AESCommon()
{
clean(state1);
clean(state2);
}
/**
* \brief Size of an AES block in bytes.
* \return Always returns 16.
*/
size_t AESCommon::blockSize() const
{
return 16;
}
// Constants to correct Galois multiplication for the high bits
// that are shifted out when multiplying by powers of two.
static uint8_t const K[8] = {
0x00,
0x1B,
(0x1B << 1),
(0x1B << 1) ^ 0x1B,
(0x1B << 2),
(0x1B << 2) ^ 0x1B,
(0x1B << 2) ^ (0x1B << 1),
(0x1B << 2) ^ (0x1B << 1) ^ 0x1B
};
// Multiply x by 2 in the Galois field, to achieve the effect of the following:
//
// if (x & 0x80)
// return (x << 1) ^ 0x1B;
// else
// return (x << 1);
//
// However, we don't want to use runtime conditionals if we can help it
// to avoid leaking timing information from the implementation.
// In this case, multiplication is slightly faster than table lookup on AVR.
#define gmul2(x) (t = ((uint16_t)(x)) << 1, \
((uint8_t)t) ^ (uint8_t)(0x1B * ((uint8_t)(t >> 8))))
// Multiply x by 4 in the Galois field.
#define gmul4(x) (t = ((uint16_t)(x)) << 2, ((uint8_t)t) ^ K[t >> 8])
// Multiply x by 8 in the Galois field.
#define gmul8(x) (t = ((uint16_t)(x)) << 3, ((uint8_t)t) ^ K[t >> 8])
#define OUT(col, row) output[(col) * 4 + (row)]
#define IN(col, row) input[(col) * 4 + (row)]
static void subBytesAndShiftRows(uint8_t *output, const uint8_t *input)
{
OUT(0, 0) = sbox[IN(0, 0)];
OUT(0, 1) = sbox[IN(1, 1)];
OUT(0, 2) = sbox[IN(2, 2)];
OUT(0, 3) = sbox[IN(3, 3)];
OUT(1, 0) = sbox[IN(1, 0)];
OUT(1, 1) = sbox[IN(2, 1)];
OUT(1, 2) = sbox[IN(3, 2)];
OUT(1, 3) = sbox[IN(0, 3)];
OUT(2, 0) = sbox[IN(2, 0)];
OUT(2, 1) = sbox[IN(3, 1)];
OUT(2, 2) = sbox[IN(0, 2)];
OUT(2, 3) = sbox[IN(1, 3)];
OUT(3, 0) = sbox[IN(3, 0)];
OUT(3, 1) = sbox[IN(0, 1)];
OUT(3, 2) = sbox[IN(1, 2)];
OUT(3, 3) = sbox[IN(2, 3)];
}
static void inverseShiftRowsAndSubBytes(uint8_t *output, const uint8_t *input)
{
OUT(0, 0) = sbox_inverse[IN(0, 0)];
OUT(0, 1) = sbox_inverse[IN(3, 1)];
OUT(0, 2) = sbox_inverse[IN(2, 2)];
OUT(0, 3) = sbox_inverse[IN(1, 3)];
OUT(1, 0) = sbox_inverse[IN(1, 0)];
OUT(1, 1) = sbox_inverse[IN(0, 1)];
OUT(1, 2) = sbox_inverse[IN(3, 2)];
OUT(1, 3) = sbox_inverse[IN(2, 3)];
OUT(2, 0) = sbox_inverse[IN(2, 0)];
OUT(2, 1) = sbox_inverse[IN(1, 1)];
OUT(2, 2) = sbox_inverse[IN(0, 2)];
OUT(2, 3) = sbox_inverse[IN(3, 3)];
OUT(3, 0) = sbox_inverse[IN(3, 0)];
OUT(3, 1) = sbox_inverse[IN(2, 1)];
OUT(3, 2) = sbox_inverse[IN(1, 2)];
OUT(3, 3) = sbox_inverse[IN(0, 3)];
}
static void mixColumn(uint8_t *output, uint8_t *input)
{
uint16_t t; // Needed by the gmul2 macro.
uint8_t a = input[0];
uint8_t b = input[1];
uint8_t c = input[2];
uint8_t d = input[3];
uint8_t a2 = gmul2(a);
uint8_t b2 = gmul2(b);
uint8_t c2 = gmul2(c);
uint8_t d2 = gmul2(d);
output[0] = a2 ^ b2 ^ b ^ c ^ d;
output[1] = a ^ b2 ^ c2 ^ c ^ d;
output[2] = a ^ b ^ c2 ^ d2 ^ d;
output[3] = a2 ^ a ^ b ^ c ^ d2;
}
static void inverseMixColumn(uint8_t *output, const uint8_t *input)
{
uint16_t t; // Needed by the gmul2, gmul4, and gmul8 macros.
uint8_t a = input[0];
uint8_t b = input[1];
uint8_t c = input[2];
uint8_t d = input[3];
uint8_t a2 = gmul2(a);
uint8_t b2 = gmul2(b);
uint8_t c2 = gmul2(c);
uint8_t d2 = gmul2(d);
uint8_t a4 = gmul4(a);
uint8_t b4 = gmul4(b);
uint8_t c4 = gmul4(c);
uint8_t d4 = gmul4(d);
uint8_t a8 = gmul8(a);
uint8_t b8 = gmul8(b);
uint8_t c8 = gmul8(c);
uint8_t d8 = gmul8(d);
output[0] = a8 ^ a4 ^ a2 ^ b8 ^ b2 ^ b ^ c8 ^ c4 ^ c ^ d8 ^ d;
output[1] = a8 ^ a ^ b8 ^ b4 ^ b2 ^ c8 ^ c2 ^ c ^ d8 ^ d4 ^ d;
output[2] = a8 ^ a4 ^ a ^ b8 ^ b ^ c8 ^ c4 ^ c2 ^ d8 ^ d2 ^ d;
output[3] = a8 ^ a2 ^ a ^ b8 ^ b4 ^ b ^ c8 ^ c ^ d8 ^ d4 ^ d2;
}
void AESCommon::encryptBlock(uint8_t *output, const uint8_t *input)
{
const uint8_t *roundKey = schedule;
uint8_t posn;
uint8_t round;
// Copy the input into the state and XOR with the first round key.
for (posn = 0; posn < 16; ++posn)
state1[posn] = input[posn] ^ roundKey[posn];
roundKey += 16;
// Perform all rounds except the last.
for (round = rounds; round > 1; --round) {
subBytesAndShiftRows(state2, state1);
mixColumn(state1, state2);
mixColumn(state1 + 4, state2 + 4);
mixColumn(state1 + 8, state2 + 8);
mixColumn(state1 + 12, state2 + 12);
for (posn = 0; posn < 16; ++posn)
state1[posn] ^= roundKey[posn];
roundKey += 16;
}
// Perform the final round.
subBytesAndShiftRows(state2, state1);
for (posn = 0; posn < 16; ++posn)
output[posn] = state2[posn] ^ roundKey[posn];
}
void AESCommon::decryptBlock(uint8_t *output, const uint8_t *input)
{
const uint8_t *roundKey = schedule + rounds * 16;
uint8_t round;
uint8_t posn;
// Copy the input into the state and reverse the final round.
for (posn = 0; posn < 16; ++posn)
state1[posn] = input[posn] ^ roundKey[posn];
inverseShiftRowsAndSubBytes(state2, state1);
// Perform all other rounds in reverse.
for (round = rounds; round > 1; --round) {
roundKey -= 16;
for (posn = 0; posn < 16; ++posn)
state2[posn] ^= roundKey[posn];
inverseMixColumn(state1, state2);
inverseMixColumn(state1 + 4, state2 + 4);
inverseMixColumn(state1 + 8, state2 + 8);
inverseMixColumn(state1 + 12, state2 + 12);
inverseShiftRowsAndSubBytes(state2, state1);
}
// Reverse the initial round and create the output words.
roundKey -= 16;
for (posn = 0; posn < 16; ++posn)
output[posn] = state2[posn] ^ roundKey[posn];
}
void AESCommon::clear()
{
clean(schedule, (rounds + 1) * 16);
clean(state1);
clean(state2);
}
/** @cond */
void AESCommon::keyScheduleCore(uint8_t *output, const uint8_t *input, uint8_t iteration)
{
// Rcon(i), 2^i in the Rijndael finite field, for i = 0..10.
// http://en.wikipedia.org/wiki/Rijndael_key_schedule
static uint8_t const rcon[11] = {
0x00, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, // 0x00
0x80, 0x1B, 0x36
};
output[0] = sbox[input[1]] ^ rcon[iteration];
output[1] = sbox[input[2]];
output[2] = sbox[input[3]];
output[3] = sbox[input[0]];
}
void AESCommon::applySbox(uint8_t *output, const uint8_t *input)
{
output[0] = sbox[input[0]];
output[1] = sbox[input[1]];
output[2] = sbox[input[2]];
output[3] = sbox[input[3]];
}
/** @endcond */
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