aes_ct_enc.c

/*
 * Copyright (c) 2016 Thomas Pornin <[email protected]>
 *
 * 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 "inner.h"

static inline void
add_round_key(uint32_t *q, const uint32_t *sk)
{
	q[0] ^= sk[0];
	q[1] ^= sk[1];
	q[2] ^= sk[2];
	q[3] ^= sk[3];
	q[4] ^= sk[4];
	q[5] ^= sk[5];
	q[6] ^= sk[6];
	q[7] ^= sk[7];
}

static inline void
shift_rows(uint32_t *q)
{
	int i;

	for (i = 0; i < 8; i ++) {
		uint32_t x;

		x = q[i];
		q[i] = (x & 0x000000FF)
			| ((x & 0x0000FC00) >> 2) | ((x & 0x00000300) << 6)
			| ((x & 0x00F00000) >> 4) | ((x & 0x000F0000) << 4)
			| ((x & 0xC0000000) >> 6) | ((x & 0x3F000000) << 2);
	}
}

static inline uint32_t
rotr16(uint32_t x)
{
	return (x << 16) | (x >> 16);
}

static inline void
mix_columns(uint32_t *q)
{
	uint32_t q0, q1, q2, q3, q4, q5, q6, q7;
	uint32_t r0, r1, r2, r3, r4, r5, r6, r7;

	q0 = q[0];
	q1 = q[1];
	q2 = q[2];
	q3 = q[3];
	q4 = q[4];
	q5 = q[5];
	q6 = q[6];
	q7 = q[7];
	r0 = (q0 >> 8) | (q0 << 24);
	r1 = (q1 >> 8) | (q1 << 24);
	r2 = (q2 >> 8) | (q2 << 24);
	r3 = (q3 >> 8) | (q3 << 24);
	r4 = (q4 >> 8) | (q4 << 24);
	r5 = (q5 >> 8) | (q5 << 24);
	r6 = (q6 >> 8) | (q6 << 24);
	r7 = (q7 >> 8) | (q7 << 24);

	q[0] = q7 ^ r7 ^ r0 ^ rotr16(q0 ^ r0);
	q[1] = q0 ^ r0 ^ q7 ^ r7 ^ r1 ^ rotr16(q1 ^ r1);
	q[2] = q1 ^ r1 ^ r2 ^ rotr16(q2 ^ r2);
	q[3] = q2 ^ r2 ^ q7 ^ r7 ^ r3 ^ rotr16(q3 ^ r3);
	q[4] = q3 ^ r3 ^ q7 ^ r7 ^ r4 ^ rotr16(q4 ^ r4);
	q[5] = q4 ^ r4 ^ r5 ^ rotr16(q5 ^ r5);
	q[6] = q5 ^ r5 ^ r6 ^ rotr16(q6 ^ r6);
	q[7] = q6 ^ r6 ^ r7 ^ rotr16(q7 ^ r7);
}

/* see inner.h */
void
br_aes_ct_bitslice_encrypt(unsigned num_rounds,
	const uint32_t *skey, uint32_t *q)
{
	unsigned u;

	add_round_key(q, skey);
	for (u = 1; u < num_rounds; u ++) {
		br_aes_ct_bitslice_Sbox(q);
		shift_rows(q);
		mix_columns(q);
		add_round_key(q, skey + (u << 3));
	}
	br_aes_ct_bitslice_Sbox(q);
	shift_rows(q);
	add_round_key(q, skey + (num_rounds << 3));
}