pqc/common/aes.c

/*
 * AES implementation based on code from BearSSL (https://bearssl.org/)
 * by Thomas Pornin.
 *
 *
 * 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 "ctaes.h"

static inline uint32_t br_dec32le(const unsigned char *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 unsigned char *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(unsigned char *dst, uint32_t x) {
    dst[0] = (unsigned char)x;
    dst[1] = (unsigned char)(x >> 8);
    dst[2] = (unsigned char)(x >> 16);
    dst[3] = (unsigned char)(x >> 24);
}


void br_range_enc32le(unsigned char *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 unsigned char 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 unsigned char *key, int key_len) {
    int i, j, k, nk, nkf;
    uint32_t tmp;
    uint32_t skey[60];
    unsigned nrounds = 10 + ((key_len - 16) >> 2);

    nk = (int)(key_len >> 2);
    nkf = (int)((nrounds + 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);
    }
}

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

    n = (nrounds + 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) {
    uint32_t t = br_swap32(*x) + 4;
    *x = br_swap32(t);
}


static void aes_ecb4x(unsigned char out[64], const uint32_t ivw[16], const uint64_t *sk_exp, unsigned int nrounds) {
    uint32_t w[16];
    uint64_t q[8];
    unsigned 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 < nrounds; 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 + 8 * nrounds);

    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);
}


static void aes_ctr4x(unsigned char out[64], uint32_t ivw[16], const uint64_t *sk_exp, unsigned int nrounds) {
    aes_ecb4x(out, ivw, sk_exp, nrounds);

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


static void aes_ecb(unsigned char *out, unsigned char *in, size_t nblocks, const uint64_t *rkeys, unsigned int nrounds) {
    uint32_t blocks[16];
    unsigned char t[64];

    while (nblocks >= 4) {
        br_range_dec32le(blocks, 16, in);
        aes_ecb4x(out, blocks, rkeys, nrounds);
        nblocks -= 4;
        in += 64;
        out += 64;
    }

    if (nblocks) {
        br_range_dec32le(blocks, nblocks * 4, in);
        aes_ecb4x(t, blocks, rkeys, nrounds);
        memcpy(out, t, nblocks * 16);
    }
}


static void aes_ctr(unsigned char *out, size_t outlen, const unsigned char *iv, const uint64_t *rkeys, unsigned int nrounds) {
    uint32_t ivw[16];
    size_t i;
    uint32_t cc = 0;

    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 (outlen > 64) {
        aes_ctr4x(out, ivw, rkeys, nrounds);
        out += 64;
        outlen -= 64;
    }
    if (outlen > 0) {
        unsigned char tmp[64];
        aes_ctr4x(tmp, ivw, rkeys, nrounds);
        for (i = 0; i < outlen; i++) {
            out[i] = tmp[i];
        }
    }
}





void aes128_keyexp(aes128ctx *r, const unsigned char *key) {
    uint64_t skey[22];

    br_aes_ct64_keysched(skey, key, 16);
    br_aes_ct64_skey_expand(r->sk_exp, skey, 10);
}


void aes192_keyexp(aes192ctx *r, const unsigned char *key) {
    uint64_t skey[26];

    br_aes_ct64_keysched(skey, key, 24);
    br_aes_ct64_skey_expand(r->sk_exp, skey, 12);
}


void aes256_keyexp(aes256ctx *r, const unsigned char *key) {
    uint64_t skey[30];

    br_aes_ct64_keysched(skey, key, 32);
    br_aes_ct64_skey_expand(r->sk_exp, skey, 14);
}


void aes128_ecb(unsigned char *out, unsigned char *in, size_t nblocks, const aes128ctx *ctx) {
    aes_ecb(out, in, nblocks, ctx->sk_exp, 10);
}

void aes128_ctr(unsigned char *out, size_t outlen, const unsigned char *iv, const aes128ctx *ctx) {
    aes_ctr(out, outlen, iv, ctx->sk_exp, 10);
}

void aes192_ecb(unsigned char *out, unsigned char *in, size_t nblocks, const aes192ctx *ctx) {
    aes_ecb(out, in, nblocks, ctx->sk_exp, 12);
}

void aes192_ctr(unsigned char *out, size_t outlen, const unsigned char *iv, const aes192ctx *ctx) {
    aes_ctr(out, outlen, iv, ctx->sk_exp, 12);
}

void aes256_ecb(unsigned char *out, unsigned char *in, size_t nblocks, const aes256ctx *ctx) {
    aes_ecb(out, in, nblocks, ctx->sk_exp, 14);
}

void aes256_ctr(unsigned char *out, size_t outlen, const unsigned char *iv, const aes256ctx *ctx) {
    aes_ctr(out, outlen, iv, ctx->sk_exp, 14);
}