/*

 * Copyright (c) 2017 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 "inner.h"

/* see bearssl_block.h */

void

br_aes_ct_ctrcbc_init(br_aes_ct_ctrcbc_keys *ctx,

  const void *key, size_t len)

{

  ctx->vtable = &br_aes_ct_ctrcbc_vtable;

  ctx->num_rounds = br_aes_ct_keysched(ctx->skey, key, len);

}

static void

xorbuf(void *dst, const void *src, size_t len)

{

  unsigned char *d;

  const unsigned char *s;

  d = dst;

  s = src;

  while (len -- > 0) {

    *d ++ ^= *s ++;

  }

}

/* see bearssl_block.h */

void

br_aes_ct_ctrcbc_ctr(const br_aes_ct_ctrcbc_keys *ctx,

  void *ctr, void *data, size_t len)

{

  unsigned char *buf;

  unsigned char *ivbuf;

  uint32_t iv0, iv1, iv2, iv3;

  uint32_t sk_exp[120];

  br_aes_ct_skey_expand(sk_exp, ctx->num_rounds, ctx->skey);

  /*

   * We keep the counter as four 32-bit values, with big-endian

   * convention, because that's what is expected for purposes of

   * incrementing the counter value.

   */

  ivbuf = ctr;

  iv0 = br_dec32be(ivbuf +  0);

  iv1 = br_dec32be(ivbuf +  4);

  iv2 = br_dec32be(ivbuf +  8);

  iv3 = br_dec32be(ivbuf + 12);

  buf = data;

  while (len > 0) {

    uint32_t q[8], carry;

    unsigned char tmp[32];

    /*

     * The bitslice implementation expects values in

     * little-endian convention, so we have to byteswap them.

     */

    q[0] = br_swap32(iv0);

    q[2] = br_swap32(iv1);

    q[4] = br_swap32(iv2);

    q[6] = br_swap32(iv3);

    iv3 ++;

    carry = ~(iv3 | -iv3) >> 31;

    iv2 += carry;

    carry &= -(~(iv2 | -iv2) >> 31);

    iv1 += carry;

    carry &= -(~(iv1 | -iv1) >> 31);

    iv0 += carry;

    q[1] = br_swap32(iv0);

    q[3] = br_swap32(iv1);

    q[5] = br_swap32(iv2);

    q[7] = br_swap32(iv3);

    if (len > 16) {

      iv3 ++;

      carry = ~(iv3 | -iv3) >> 31;

      iv2 += carry;

      carry &= -(~(iv2 | -iv2) >> 31);

      iv1 += carry;

      carry &= -(~(iv1 | -iv1) >> 31);

      iv0 += carry;

    }

    br_aes_ct_ortho(q);

    br_aes_ct_bitslice_encrypt(ctx->num_rounds, sk_exp, q);

    br_aes_ct_ortho(q);

    br_enc32le(tmp, q[0]);

    br_enc32le(tmp + 4, q[2]);

    br_enc32le(tmp + 8, q[4]);

    br_enc32le(tmp + 12, q[6]);

    br_enc32le(tmp + 16, q[1]);

    br_enc32le(tmp + 20, q[3]);

    br_enc32le(tmp + 24, q[5]);

    br_enc32le(tmp + 28, q[7]);

    if (len <= 32) {

      xorbuf(buf, tmp, len);

      break;

    }

    xorbuf(buf, tmp, 32);

    buf += 32;

    len -= 32;

  }

  br_enc32be(ivbuf +  0, iv0);

  br_enc32be(ivbuf +  4, iv1);

  br_enc32be(ivbuf +  8, iv2);

  br_enc32be(ivbuf + 12, iv3);

}

/* see bearssl_block.h */

void

br_aes_ct_ctrcbc_mac(const br_aes_ct_ctrcbc_keys *ctx,

  void *cbcmac, const void *data, size_t len)

{

  const unsigned char *buf;

  uint32_t cm0, cm1, cm2, cm3;

  uint32_t q[8];

  uint32_t sk_exp[120];

  br_aes_ct_skey_expand(sk_exp, ctx->num_rounds, ctx->skey);

  buf = data;

  cm0 = br_dec32le((unsigned char *)cbcmac +  0);

  cm1 = br_dec32le((unsigned char *)cbcmac +  4);

  cm2 = br_dec32le((unsigned char *)cbcmac +  8);

  cm3 = br_dec32le((unsigned char *)cbcmac + 12);

  q[1] = 0;

  q[3] = 0;

  q[5] = 0;

  q[7] = 0;

  while (len > 0) {

    q[0] = cm0 ^ br_dec32le(buf +  0);

    q[2] = cm1 ^ br_dec32le(buf +  4);

    q[4] = cm2 ^ br_dec32le(buf +  8);

    q[6] = cm3 ^ br_dec32le(buf + 12);

    br_aes_ct_ortho(q);

    br_aes_ct_bitslice_encrypt(ctx->num_rounds, sk_exp, q);

    br_aes_ct_ortho(q);

    cm0 = q[0];

    cm1 = q[2];

    cm2 = q[4];

    cm3 = q[6];

    buf += 16;

    len -= 16;

  }

  br_enc32le((unsigned char *)cbcmac +  0, cm0);

  br_enc32le((unsigned char *)cbcmac +  4, cm1);

  br_enc32le((unsigned char *)cbcmac +  8, cm2);

  br_enc32le((unsigned char *)cbcmac + 12, cm3);

}

/* see bearssl_block.h */

void

br_aes_ct_ctrcbc_encrypt(const br_aes_ct_ctrcbc_keys *ctx,

  void *ctr, void *cbcmac, void *data, size_t len)

{

  /*

   * When encrypting, the CBC-MAC processing must be lagging by

   * one block, since it operates on the encrypted values, so

   * it must wait for that encryption to complete.

   */

  unsigned char *buf;

  unsigned char *ivbuf;

  uint32_t iv0, iv1, iv2, iv3;

  uint32_t cm0, cm1, cm2, cm3;

  uint32_t sk_exp[120];

  int first_iter;

  br_aes_ct_skey_expand(sk_exp, ctx->num_rounds, ctx->skey);

  /*

   * We keep the counter as four 32-bit values, with big-endian

   * convention, because that's what is expected for purposes of

   * incrementing the counter value.

   */

  ivbuf = ctr;

  iv0 = br_dec32be(ivbuf +  0);

  iv1 = br_dec32be(ivbuf +  4);

  iv2 = br_dec32be(ivbuf +  8);

  iv3 = br_dec32be(ivbuf + 12);

  /*

   * The current CBC-MAC value is kept in little-endian convention.

   */

  cm0 = br_dec32le((unsigned char *)cbcmac +  0);

  cm1 = br_dec32le((unsigned char *)cbcmac +  4);

  cm2 = br_dec32le((unsigned char *)cbcmac +  8);

  cm3 = br_dec32le((unsigned char *)cbcmac + 12);

  buf = data;

  first_iter = 1;

  while (len > 0) {

    uint32_t q[8], carry;

    /*

     * The bitslice implementation expects values in

     * little-endian convention, so we have to byteswap them.

     */

    q[0] = br_swap32(iv0);

    q[2] = br_swap32(iv1);

    q[4] = br_swap32(iv2);

    q[6] = br_swap32(iv3);

    iv3 ++;

    carry = ~(iv3 | -iv3) >> 31;

    iv2 += carry;

    carry &= -(~(iv2 | -iv2) >> 31);

    iv1 += carry;

    carry &= -(~(iv1 | -iv1) >> 31);

    iv0 += carry;

    /*

     * The odd values are used for CBC-MAC.

     */

    q[1] = cm0;

    q[3] = cm1;

    q[5] = cm2;

    q[7] = cm3;

    br_aes_ct_ortho(q);

    br_aes_ct_bitslice_encrypt(ctx->num_rounds, sk_exp, q);

    br_aes_ct_ortho(q);

    /*

     * We do the XOR with the plaintext in 32-bit registers,

     * so that the value are available for CBC-MAC processing

     * as well.

     */

    q[0] ^= br_dec32le(buf +  0);

    q[2] ^= br_dec32le(buf +  4);

    q[4] ^= br_dec32le(buf +  8);

    q[6] ^= br_dec32le(buf + 12);

    br_enc32le(buf +  0, q[0]);

    br_enc32le(buf +  4, q[2]);

    br_enc32le(buf +  8, q[4]);

    br_enc32le(buf + 12, q[6]);

    buf += 16;

    len -= 16;

    /*

     * We set the cm* values to the block to encrypt in the

     * next iteration.

     */

    if (first_iter) {

      first_iter = 0;

      cm0 ^= q[0];

      cm1 ^= q[2];

      cm2 ^= q[4];

      cm3 ^= q[6];

    } else {

      cm0 = q[0] ^ q[1];

      cm1 = q[2] ^ q[3];

      cm2 = q[4] ^ q[5];

      cm3 = q[6] ^ q[7];

    }

    /*

     * If this was the last iteration, then compute the

     * extra block encryption to complete CBC-MAC.

     */

    if (len == 0) {

      q[0] = cm0;

      q[2] = cm1;

      q[4] = cm2;

      q[6] = cm3;

      br_aes_ct_ortho(q);

      br_aes_ct_bitslice_encrypt(ctx->num_rounds, sk_exp, q);

      br_aes_ct_ortho(q);

      cm0 = q[0];

      cm1 = q[2];

      cm2 = q[4];

      cm3 = q[6];

      break;

    }

  }

  br_enc32be(ivbuf +  0, iv0);

  br_enc32be(ivbuf +  4, iv1);

  br_enc32be(ivbuf +  8, iv2);

  br_enc32be(ivbuf + 12, iv3);

  br_enc32le((unsigned char *)cbcmac +  0, cm0);

  br_enc32le((unsigned char *)cbcmac +  4, cm1);

  br_enc32le((unsigned char *)cbcmac +  8, cm2);

  br_enc32le((unsigned char *)cbcmac + 12, cm3);

}

/* see bearssl_block.h */

void

br_aes_ct_ctrcbc_decrypt(const br_aes_ct_ctrcbc_keys *ctx,

  void *ctr, void *cbcmac, void *data, size_t len)

{

  unsigned char *buf;

  unsigned char *ivbuf;

  uint32_t iv0, iv1, iv2, iv3;

  uint32_t cm0, cm1, cm2, cm3;

  uint32_t sk_exp[120];

  br_aes_ct_skey_expand(sk_exp, ctx->num_rounds, ctx->skey);

  /*

   * We keep the counter as four 32-bit values, with big-endian

   * convention, because that's what is expected for purposes of

   * incrementing the counter value.

   */

  ivbuf = ctr;

  iv0 = br_dec32be(ivbuf +  0);

  iv1 = br_dec32be(ivbuf +  4);

  iv2 = br_dec32be(ivbuf +  8);

  iv3 = br_dec32be(ivbuf + 12);

  /*

   * The current CBC-MAC value is kept in little-endian convention.

   */

  cm0 = br_dec32le((unsigned char *)cbcmac +  0);

  cm1 = br_dec32le((unsigned char *)cbcmac +  4);

  cm2 = br_dec32le((unsigned char *)cbcmac +  8);

  cm3 = br_dec32le((unsigned char *)cbcmac + 12);

  buf = data;

  while (len > 0) {

    uint32_t q[8], carry;

    unsigned char tmp[16];

    /*

     * The bitslice implementation expects values in

     * little-endian convention, so we have to byteswap them.

     */

    q[0] = br_swap32(iv0);

    q[2] = br_swap32(iv1);

    q[4] = br_swap32(iv2);

    q[6] = br_swap32(iv3);

    iv3 ++;

    carry = ~(iv3 | -iv3) >> 31;

    iv2 += carry;

    carry &= -(~(iv2 | -iv2) >> 31);

    iv1 += carry;

    carry &= -(~(iv1 | -iv1) >> 31);

    iv0 += carry;

    /*

     * The odd values are used for CBC-MAC.

     */

    q[1] = cm0 ^ br_dec32le(buf +  0);

    q[3] = cm1 ^ br_dec32le(buf +  4);

    q[5] = cm2 ^ br_dec32le(buf +  8);

    q[7] = cm3 ^ br_dec32le(buf + 12);

    br_aes_ct_ortho(q);

    br_aes_ct_bitslice_encrypt(ctx->num_rounds, sk_exp, q);

    br_aes_ct_ortho(q);

    br_enc32le(tmp +  0, q[0]);

    br_enc32le(tmp +  4, q[2]);

    br_enc32le(tmp +  8, q[4]);

    br_enc32le(tmp + 12, q[6]);

    xorbuf(buf, tmp, 16);

    cm0 = q[1];

    cm1 = q[3];

    cm2 = q[5];

    cm3 = q[7];

    buf += 16;

    len -= 16;

  }

  br_enc32be(ivbuf +  0, iv0);

  br_enc32be(ivbuf +  4, iv1);

  br_enc32be(ivbuf +  8, iv2);

  br_enc32be(ivbuf + 12, iv3);

  br_enc32le((unsigned char *)cbcmac +  0, cm0);

  br_enc32le((unsigned char *)cbcmac +  4, cm1);

  br_enc32le((unsigned char *)cbcmac +  8, cm2);

  br_enc32le((unsigned char *)cbcmac + 12, cm3);

}

/* see bearssl_block.h */

const br_block_ctrcbc_class br_aes_ct_ctrcbc_vtable = {

  sizeof(br_aes_ct_ctrcbc_keys),

  16,

  4,

  (void (*)(const br_block_ctrcbc_class **, const void *, size_t))

    &br_aes_ct_ctrcbc_init,

  (void (*)(const br_block_ctrcbc_class *const *,

    void *, void *, void *, size_t))

    &br_aes_ct_ctrcbc_encrypt,

  (void (*)(const br_block_ctrcbc_class *const *,

    void *, void *, void *, size_t))

    &br_aes_ct_ctrcbc_decrypt,

  (void (*)(const br_block_ctrcbc_class *const *,

    void *, void *, size_t))

    &br_aes_ct_ctrcbc_ctr,

  (void (*)(const br_block_ctrcbc_class *const *,

    void *, const void *, size_t))

    &br_aes_ct_ctrcbc_mac

};