aes256ctr.c

/*
 * Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
 *
 * 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 <stdint.h>
#include <string.h>
#include "aes256ctr.h"

static inline uint32_t br_dec32le(const uint8_t *src)
{
	return (uint32_t)src[0]
		| ((uint32_t)src[1] << 8)
		| ((uint32_t)src[2] << 16)
		| ((uint32_t)src[3] << 24);
}

static void br_range_dec32le(uint32_t *v, size_t num, const uint8_t *src)
{
	while (num-- > 0) {
		*v ++ = br_dec32le(src);
		src += 4;
	}
}

static inline uint32_t br_swap32(uint32_t x)
{
	x = ((x & (uint32_t)0x00FF00FF) << 8)
		| ((x >> 8) & (uint32_t)0x00FF00FF);
	return (x << 16) | (x >> 16);
}

static inline void br_enc32le(uint8_t *dst, uint32_t x)
{
	dst[0] = (uint8_t)x;
	dst[1] = (uint8_t)(x >> 8);
	dst[2] = (uint8_t)(x >> 16);
	dst[3] = (uint8_t)(x >> 24);
}

static void br_range_enc32le(uint8_t *dst, const uint32_t *v, size_t num)
{
	while (num-- > 0) {
		br_enc32le(dst, *v ++);
		dst += 4;
	}
}

static void br_aes_ct64_bitslice_Sbox(uint64_t *q)
{
	/*
	 * This S-box implementation is a straightforward translation of
	 * the circuit described by Boyar and Peralta in "A new
	 * combinational logic minimization technique with applications
	 * to cryptology" (https://eprint.iacr.org/2009/191.pdf).
	 *
	 * Note that variables x* (input) and s* (output) are numbered
	 * in "reverse" order (x0 is the high bit, x7 is the low bit).
	 */

	uint64_t x0, x1, x2, x3, x4, x5, x6, x7;
	uint64_t y1, y2, y3, y4, y5, y6, y7, y8, y9;
	uint64_t y10, y11, y12, y13, y14, y15, y16, y17, y18, y19;
	uint64_t y20, y21;
	uint64_t z0, z1, z2, z3, z4, z5, z6, z7, z8, z9;
	uint64_t z10, z11, z12, z13, z14, z15, z16, z17;
	uint64_t t0, t1, t2, t3, t4, t5, t6, t7, t8, t9;
	uint64_t t10, t11, t12, t13, t14, t15, t16, t17, t18, t19;
	uint64_t t20, t21, t22, t23, t24, t25, t26, t27, t28, t29;
	uint64_t t30, t31, t32, t33, t34, t35, t36, t37, t38, t39;
	uint64_t t40, t41, t42, t43, t44, t45, t46, t47, t48, t49;
	uint64_t t50, t51, t52, t53, t54, t55, t56, t57, t58, t59;
	uint64_t t60, t61, t62, t63, t64, t65, t66, t67;
	uint64_t s0, s1, s2, s3, s4, s5, s6, s7;

	x0 = q[7];
	x1 = q[6];
	x2 = q[5];
	x3 = q[4];
	x4 = q[3];
	x5 = q[2];
	x6 = q[1];
	x7 = q[0];

	/*
	 * Top linear transformation.
	 */
	y14 = x3 ^ x5;
	y13 = x0 ^ x6;
	y9 = x0 ^ x3;
	y8 = x0 ^ x5;
	t0 = x1 ^ x2;
	y1 = t0 ^ x7;
	y4 = y1 ^ x3;
	y12 = y13 ^ y14;
	y2 = y1 ^ x0;
	y5 = y1 ^ x6;
	y3 = y5 ^ y8;
	t1 = x4 ^ y12;
	y15 = t1 ^ x5;
	y20 = t1 ^ x1;
	y6 = y15 ^ x7;
	y10 = y15 ^ t0;
	y11 = y20 ^ y9;
	y7 = x7 ^ y11;
	y17 = y10 ^ y11;
	y19 = y10 ^ y8;
	y16 = t0 ^ y11;
	y21 = y13 ^ y16;
	y18 = x0 ^ y16;

	/*
	 * Non-linear section.
	 */
	t2 = y12 & y15;
	t3 = y3 & y6;
	t4 = t3 ^ t2;
	t5 = y4 & x7;
	t6 = t5 ^ t2;
	t7 = y13 & y16;
	t8 = y5 & y1;
	t9 = t8 ^ t7;
	t10 = y2 & y7;
	t11 = t10 ^ t7;
	t12 = y9 & y11;
	t13 = y14 & y17;
	t14 = t13 ^ t12;
	t15 = y8 & y10;
	t16 = t15 ^ t12;
	t17 = t4 ^ t14;
	t18 = t6 ^ t16;
	t19 = t9 ^ t14;
	t20 = t11 ^ t16;
	t21 = t17 ^ y20;
	t22 = t18 ^ y19;
	t23 = t19 ^ y21;
	t24 = t20 ^ y18;

	t25 = t21 ^ t22;
	t26 = t21 & t23;
	t27 = t24 ^ t26;
	t28 = t25 & t27;
	t29 = t28 ^ t22;
	t30 = t23 ^ t24;
	t31 = t22 ^ t26;
	t32 = t31 & t30;
	t33 = t32 ^ t24;
	t34 = t23 ^ t33;
	t35 = t27 ^ t33;
	t36 = t24 & t35;
	t37 = t36 ^ t34;
	t38 = t27 ^ t36;
	t39 = t29 & t38;
	t40 = t25 ^ t39;

	t41 = t40 ^ t37;
	t42 = t29 ^ t33;
	t43 = t29 ^ t40;
	t44 = t33 ^ t37;
	t45 = t42 ^ t41;
	z0 = t44 & y15;
	z1 = t37 & y6;
	z2 = t33 & x7;
	z3 = t43 & y16;
	z4 = t40 & y1;
	z5 = t29 & y7;
	z6 = t42 & y11;
	z7 = t45 & y17;
	z8 = t41 & y10;
	z9 = t44 & y12;
	z10 = t37 & y3;
	z11 = t33 & y4;
	z12 = t43 & y13;
	z13 = t40 & y5;
	z14 = t29 & y2;
	z15 = t42 & y9;
	z16 = t45 & y14;
	z17 = t41 & y8;

	/*
	 * Bottom linear transformation.
	 */
	t46 = z15 ^ z16;
	t47 = z10 ^ z11;
	t48 = z5 ^ z13;
	t49 = z9 ^ z10;
	t50 = z2 ^ z12;
	t51 = z2 ^ z5;
	t52 = z7 ^ z8;
	t53 = z0 ^ z3;
	t54 = z6 ^ z7;
	t55 = z16 ^ z17;
	t56 = z12 ^ t48;
	t57 = t50 ^ t53;
	t58 = z4 ^ t46;
	t59 = z3 ^ t54;
	t60 = t46 ^ t57;
	t61 = z14 ^ t57;
	t62 = t52 ^ t58;
	t63 = t49 ^ t58;
	t64 = z4 ^ t59;
	t65 = t61 ^ t62;
	t66 = z1 ^ t63;
	s0 = t59 ^ t63;
	s6 = t56 ^ ~t62;
	s7 = t48 ^ ~t60;
	t67 = t64 ^ t65;
	s3 = t53 ^ t66;
	s4 = t51 ^ t66;
	s5 = t47 ^ t65;
	s1 = t64 ^ ~s3;
	s2 = t55 ^ ~t67;

	q[7] = s0;
	q[6] = s1;
	q[5] = s2;
	q[4] = s3;
	q[3] = s4;
	q[2] = s5;
	q[1] = s6;
	q[0] = s7;
}

static void br_aes_ct64_ortho(uint64_t *q)
{
#define SWAPN(cl, ch, s, x, y)   do { \
		uint64_t a, b; \
		a = (x); \
		b = (y); \
		(x) = (a & (uint64_t)cl) | ((b & (uint64_t)cl) << (s)); \
		(y) = ((a & (uint64_t)ch) >> (s)) | (b & (uint64_t)ch); \
	} while (0)

#define SWAP2(x, y)    SWAPN(0x5555555555555555, 0xAAAAAAAAAAAAAAAA,  1, x, y)
#define SWAP4(x, y)    SWAPN(0x3333333333333333, 0xCCCCCCCCCCCCCCCC,  2, x, y)
#define SWAP8(x, y)    SWAPN(0x0F0F0F0F0F0F0F0F, 0xF0F0F0F0F0F0F0F0,  4, x, y)

	SWAP2(q[0], q[1]);
	SWAP2(q[2], q[3]);
	SWAP2(q[4], q[5]);
	SWAP2(q[6], q[7]);

	SWAP4(q[0], q[2]);
	SWAP4(q[1], q[3]);
	SWAP4(q[4], q[6]);
	SWAP4(q[5], q[7]);

	SWAP8(q[0], q[4]);
	SWAP8(q[1], q[5]);
	SWAP8(q[2], q[6]);
	SWAP8(q[3], q[7]);
}

static void br_aes_ct64_interleave_in(uint64_t *q0, uint64_t *q1, const uint32_t *w)
{
	uint64_t x0, x1, x2, x3;

	x0 = w[0];
	x1 = w[1];
	x2 = w[2];
	x3 = w[3];
	x0 |= (x0 << 16);
	x1 |= (x1 << 16);
	x2 |= (x2 << 16);
	x3 |= (x3 << 16);
	x0 &= (uint64_t)0x0000FFFF0000FFFF;
	x1 &= (uint64_t)0x0000FFFF0000FFFF;
	x2 &= (uint64_t)0x0000FFFF0000FFFF;
	x3 &= (uint64_t)0x0000FFFF0000FFFF;
	x0 |= (x0 << 8);
	x1 |= (x1 << 8);
	x2 |= (x2 << 8);
	x3 |= (x3 << 8);
	x0 &= (uint64_t)0x00FF00FF00FF00FF;
	x1 &= (uint64_t)0x00FF00FF00FF00FF;
	x2 &= (uint64_t)0x00FF00FF00FF00FF;
	x3 &= (uint64_t)0x00FF00FF00FF00FF;
	*q0 = x0 | (x2 << 8);
	*q1 = x1 | (x3 << 8);
}

static void br_aes_ct64_interleave_out(uint32_t *w, uint64_t q0, uint64_t q1)
{
	uint64_t x0, x1, x2, x3;

	x0 = q0 & (uint64_t)0x00FF00FF00FF00FF;
	x1 = q1 & (uint64_t)0x00FF00FF00FF00FF;
	x2 = (q0 >> 8) & (uint64_t)0x00FF00FF00FF00FF;
	x3 = (q1 >> 8) & (uint64_t)0x00FF00FF00FF00FF;
	x0 |= (x0 >> 8);
	x1 |= (x1 >> 8);
	x2 |= (x2 >> 8);
	x3 |= (x3 >> 8);
	x0 &= (uint64_t)0x0000FFFF0000FFFF;
	x1 &= (uint64_t)0x0000FFFF0000FFFF;
	x2 &= (uint64_t)0x0000FFFF0000FFFF;
	x3 &= (uint64_t)0x0000FFFF0000FFFF;
	w[0] = (uint32_t)x0 | (uint32_t)(x0 >> 16);
	w[1] = (uint32_t)x1 | (uint32_t)(x1 >> 16);
	w[2] = (uint32_t)x2 | (uint32_t)(x2 >> 16);
	w[3] = (uint32_t)x3 | (uint32_t)(x3 >> 16);
}

static const uint8_t Rcon[] = {
	0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1B, 0x36
};

static uint32_t sub_word(uint32_t x)
{
	uint64_t q[8];

	memset(q, 0, sizeof q);
	q[0] = x;
	br_aes_ct64_ortho(q);
	br_aes_ct64_bitslice_Sbox(q);
	br_aes_ct64_ortho(q);
	return (uint32_t)q[0];
}

static void br_aes_ct64_keysched(uint64_t *comp_skey, const uint8_t *key)
{
	int i, j, k, nk, nkf;
	uint32_t tmp;
	uint32_t skey[60];

	int key_len = 32;

	nk = (int)(key_len >> 2);
	nkf = (int)((14 + 1) << 2);
	br_range_dec32le(skey, (key_len >> 2), key);
	tmp = skey[(key_len >> 2) - 1];
	for (i = nk, j = 0, k = 0; i < nkf; i ++) {
		if (j == 0) {
			tmp = (tmp << 24) | (tmp >> 8);
			tmp = sub_word(tmp) ^ Rcon[k];
		} else if (nk > 6 && j == 4) {
			tmp = sub_word(tmp);
		}
		tmp ^= skey[i - nk];
		skey[i] = tmp;
		if (++ j == nk) {
			j = 0;
			k ++;
		}
	}

	for (i = 0, j = 0; i < nkf; i += 4, j += 2) {
		uint64_t q[8];

		br_aes_ct64_interleave_in(&q[0], &q[4], skey + i);
		q[1] = q[0];
		q[2] = q[0];
		q[3] = q[0];
		q[5] = q[4];
		q[6] = q[4];
		q[7] = q[4];
		br_aes_ct64_ortho(q);
		comp_skey[j + 0] =
			  (q[0] & (uint64_t)0x1111111111111111)
			| (q[1] & (uint64_t)0x2222222222222222)
			| (q[2] & (uint64_t)0x4444444444444444)
			| (q[3] & (uint64_t)0x8888888888888888);
		comp_skey[j + 1] =
			  (q[4] & (uint64_t)0x1111111111111111)
			| (q[5] & (uint64_t)0x2222222222222222)
			| (q[6] & (uint64_t)0x4444444444444444)
			| (q[7] & (uint64_t)0x8888888888888888);
	}
}

static void br_aes_ct64_skey_expand(uint64_t *skey, const uint64_t *comp_skey)
{
	unsigned u, v, n;

	n = (14 + 1) << 1;
	for (u = 0, v = 0; u < n; u ++, v += 4) {
		uint64_t x0, x1, x2, x3;

		x0 = x1 = x2 = x3 = comp_skey[u];
		x0 &= (uint64_t)0x1111111111111111;
		x1 &= (uint64_t)0x2222222222222222;
		x2 &= (uint64_t)0x4444444444444444;
		x3 &= (uint64_t)0x8888888888888888;
		x1 >>= 1;
		x2 >>= 2;
		x3 >>= 3;
		skey[v + 0] = (x0 << 4) - x0;
		skey[v + 1] = (x1 << 4) - x1;
		skey[v + 2] = (x2 << 4) - x2;
		skey[v + 3] = (x3 << 4) - x3;
	}
}

static inline void add_round_key(uint64_t *q, const uint64_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(uint64_t *q)
{
	int i;

	for (i = 0; i < 8; i ++) {
		uint64_t x;

		x = q[i];
		q[i] = (x & (uint64_t)0x000000000000FFFF)
			| ((x & (uint64_t)0x00000000FFF00000) >> 4)
			| ((x & (uint64_t)0x00000000000F0000) << 12)
			| ((x & (uint64_t)0x0000FF0000000000) >> 8)
			| ((x & (uint64_t)0x000000FF00000000) << 8)
			| ((x & (uint64_t)0xF000000000000000) >> 12)
			| ((x & (uint64_t)0x0FFF000000000000) << 4);
	}
}

static inline uint64_t rotr32(uint64_t x)
{
	return (x << 32) | (x >> 32);
}

static inline void mix_columns(uint64_t *q)
{
	uint64_t q0, q1, q2, q3, q4, q5, q6, q7;
	uint64_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 >> 16) | (q0 << 48);
	r1 = (q1 >> 16) | (q1 << 48);
	r2 = (q2 >> 16) | (q2 << 48);
	r3 = (q3 >> 16) | (q3 << 48);
	r4 = (q4 >> 16) | (q4 << 48);
	r5 = (q5 >> 16) | (q5 << 48);
	r6 = (q6 >> 16) | (q6 << 48);
	r7 = (q7 >> 16) | (q7 << 48);

	q[0] = q7 ^ r7 ^ r0 ^ rotr32(q0 ^ r0);
	q[1] = q0 ^ r0 ^ q7 ^ r7 ^ r1 ^ rotr32(q1 ^ r1);
	q[2] = q1 ^ r1 ^ r2 ^ rotr32(q2 ^ r2);
	q[3] = q2 ^ r2 ^ q7 ^ r7 ^ r3 ^ rotr32(q3 ^ r3);
	q[4] = q3 ^ r3 ^ q7 ^ r7 ^ r4 ^ rotr32(q4 ^ r4);
	q[5] = q4 ^ r4 ^ r5 ^ rotr32(q5 ^ r5);
	q[6] = q5 ^ r5 ^ r6 ^ rotr32(q6 ^ r6);
	q[7] = q6 ^ r6 ^ r7 ^ rotr32(q7 ^ r7);
}

static void inc4_be(uint32_t *x)
{
  *x = br_swap32(*x)+4;
  *x = br_swap32(*x);
}

static void aes_ctr4x(uint8_t out[64], uint32_t ivw[16], uint64_t sk_exp[120])
{
  uint32_t w[16];
  uint64_t q[8];
  int i;

  memcpy(w, ivw, sizeof(w));
  for (i = 0; i < 4; i++) {
    br_aes_ct64_interleave_in(&q[i], &q[i + 4], w + (i << 2));
  }
  br_aes_ct64_ortho(q);

  add_round_key(q, sk_exp);
  for (i = 1; i < 14; i++) {
    br_aes_ct64_bitslice_Sbox(q);
    shift_rows(q);
    mix_columns(q);
    add_round_key(q, sk_exp + (i << 3));
  }
  br_aes_ct64_bitslice_Sbox(q);
  shift_rows(q);
  add_round_key(q, sk_exp + 112);

  br_aes_ct64_ortho(q);
  for (i = 0; i < 4; i ++) {
    br_aes_ct64_interleave_out(w + (i << 2), q[i], q[i + 4]);
  }
  br_range_enc32le(out, w, 16);

  /* Increase counter for next 4 blocks */
  inc4_be(ivw+3);
  inc4_be(ivw+7);
  inc4_be(ivw+11);
  inc4_be(ivw+15);
}

static void br_aes_ct64_ctr_init(uint64_t sk_exp[120], const uint8_t *key)
{
	uint64_t skey[30];

	br_aes_ct64_keysched(skey, key);
	br_aes_ct64_skey_expand(sk_exp, skey);
}

static void br_aes_ct64_ctr_run(uint64_t sk_exp[120], const uint8_t *iv, uint32_t cc, uint8_t *data, size_t len)
{
	uint32_t ivw[16];
	size_t i;

	br_range_dec32le(ivw, 3, iv);
	memcpy(ivw +  4, ivw, 3 * sizeof(uint32_t));
	memcpy(ivw +  8, ivw, 3 * sizeof(uint32_t));
	memcpy(ivw + 12, ivw, 3 * sizeof(uint32_t));
	ivw[ 3] = br_swap32(cc);
	ivw[ 7] = br_swap32(cc + 1);
	ivw[11] = br_swap32(cc + 2);
	ivw[15] = br_swap32(cc + 3);

	while (len > 64) {
		aes_ctr4x(data, ivw, sk_exp);
		data += 64;
		len -= 64;
	}
	if(len > 0) {
		uint8_t tmp[64];
		aes_ctr4x(tmp, ivw, sk_exp);
		for(i=0;i<len;i++)
			data[i] = tmp[i];
	}
}

void aes256ctr_prf(uint8_t *out, size_t outlen, const uint8_t key[32], const uint8_t nonce[12])
{
  uint64_t sk_exp[120];

  br_aes_ct64_ctr_init(sk_exp, key);
  br_aes_ct64_ctr_run(sk_exp, nonce, 0, out, outlen);
}

void aes256ctr_init(aes256ctr_ctx *s, const uint8_t key[32], const uint8_t nonce[12])
{
  br_aes_ct64_ctr_init(s->sk_exp, key);

  br_range_dec32le(s->ivw, 3, nonce);
  memcpy(s->ivw +  4, s->ivw, 3 * sizeof(uint32_t));
  memcpy(s->ivw +  8, s->ivw, 3 * sizeof(uint32_t));
  memcpy(s->ivw + 12, s->ivw, 3 * sizeof(uint32_t));
  s->ivw[ 3] = br_swap32(0);
  s->ivw[ 7] = br_swap32(1);
  s->ivw[11] = br_swap32(2);
  s->ivw[15] = br_swap32(3);
}

void aes256ctr_squeezeblocks(uint8_t *out, size_t nblocks, aes256ctr_ctx *s)
{
  while (nblocks > 0) {
    aes_ctr4x(out, s->ivw, s->sk_exp);
    out += 64;
    nblocks--;
  }
}