/*

 * 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_big_ctrcbc_init(br_aes_big_ctrcbc_keys *ctx,

  const void *key, size_t len)

{

  ctx->vtable = &br_aes_big_ctrcbc_vtable;

  ctx->num_rounds = br_aes_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_big_ctrcbc_ctr(const br_aes_big_ctrcbc_keys *ctx,

  void *ctr, void *data, size_t len)

{

  unsigned char *buf, *bctr;

  uint32_t cc0, cc1, cc2, cc3;

  buf = data;

  bctr = ctr;

  cc3 = br_dec32be(bctr +  0);

  cc2 = br_dec32be(bctr +  4);

  cc1 = br_dec32be(bctr +  8);

  cc0 = br_dec32be(bctr + 12);

  while (len > 0) {

    unsigned char tmp[16];

    uint32_t carry;

    br_enc32be(tmp +  0, cc3);

    br_enc32be(tmp +  4, cc2);

    br_enc32be(tmp +  8, cc1);

    br_enc32be(tmp + 12, cc0);

    br_aes_big_encrypt(ctx->num_rounds, ctx->skey, tmp);

    xorbuf(buf, tmp, 16);

    buf += 16;

    len -= 16;

    cc0 ++;

    carry = (~(cc0 | -cc0)) >> 31;

    cc1 += carry;

    carry &= (~(cc1 | -cc1)) >> 31;

    cc2 += carry;

    carry &= (~(cc2 | -cc2)) >> 31;

    cc3 += carry;

  }

  br_enc32be(bctr +  0, cc3);

  br_enc32be(bctr +  4, cc2);

  br_enc32be(bctr +  8, cc1);

  br_enc32be(bctr + 12, cc0);

}

/* see bearssl_block.h */

void

br_aes_big_ctrcbc_mac(const br_aes_big_ctrcbc_keys *ctx,

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

{

  const unsigned char *buf;

  buf = data;

  while (len > 0) {

    xorbuf(cbcmac, buf, 16);

    br_aes_big_encrypt(ctx->num_rounds, ctx->skey, cbcmac);

    buf += 16;

    len -= 16;

  }

}

/* see bearssl_block.h */

void

br_aes_big_ctrcbc_encrypt(const br_aes_big_ctrcbc_keys *ctx,

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

{

  br_aes_big_ctrcbc_ctr(ctx, ctr, data, len);

  br_aes_big_ctrcbc_mac(ctx, cbcmac, data, len);

}

/* see bearssl_block.h */

void

br_aes_big_ctrcbc_decrypt(const br_aes_big_ctrcbc_keys *ctx,

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

{

  br_aes_big_ctrcbc_mac(ctx, cbcmac, data, len);

  br_aes_big_ctrcbc_ctr(ctx, ctr, data, len);

}

/* see bearssl_block.h */

const br_block_ctrcbc_class br_aes_big_ctrcbc_vtable = {

  sizeof(br_aes_big_ctrcbc_keys),

  16,

  4,

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

    &br_aes_big_ctrcbc_init,

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

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

    &br_aes_big_ctrcbc_encrypt,

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

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

    &br_aes_big_ctrcbc_decrypt,

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

    void *, void *, size_t))

    &br_aes_big_ctrcbc_ctr,

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

    void *, const void *, size_t))

    &br_aes_big_ctrcbc_mac

};