osfmk/corecrypto/ccmode/src/ccmode_ctr_crypt.c

   1 /*
   2  *  ccmode_ctr_crypt.c
   3  *  corecrypto
   4  *
   5  *  Created on 12/17/2010
   6  *
   7  *  Copyright (c) 2010,2011,2012,2014,2015 Apple Inc. All rights reserved.
   8  *
   9  *
  10  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
  11  *
  12  * This file contains Original Code and/or Modifications of Original Code
  13  * as defined in and that are subject to the Apple Public Source License
  14  * Version 2.0 (the 'License'). You may not use this file except in
  15  * compliance with the License. The rights granted to you under the License
  16  * may not be used to create, or enable the creation or redistribution of,
  17  * unlawful or unlicensed copies of an Apple operating system, or to
  18  * circumvent, violate, or enable the circumvention or violation of, any
  19  * terms of an Apple operating system software license agreement.
  20  *
  21  * Please obtain a copy of the License at
  22  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  23  *
  24  * The Original Code and all software distributed under the License are
  25  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  26  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  27  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  28  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  29  * Please see the License for the specific language governing rights and
  30  * limitations under the License.
  31  *
  32  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  33  */
  34
  35 #include "ccmode_internal.h"
  36
  37 int ccmode_ctr_crypt(ccctr_ctx *key,
  38                      size_t nbytes, const void *in, void *out) {
  39     const struct ccmode_ecb *ecb = CCMODE_CTR_KEY_ECB(key);
  40     const ccecb_ctx *ecb_key = CCMODE_CTR_KEY_ECB_KEY(key);
  41     uint8_t *ctr = (uint8_t *)CCMODE_CTR_KEY_CTR(key);
  42     uint8_t *pad = (uint8_t *)CCMODE_CTR_KEY_PAD(key);
  43     size_t pad_offset = CCMODE_CTR_KEY_PAD_OFFSET(key);
  44     const uint8_t *in_bytes = in;
  45     // Counter is 64bit wide for cipher with block size of 64bit or more
  46     // This is to match the assembly
  47     const size_t counter_size=(CC_MIN(ecb->block_size,(typeof(ecb->block_size))8));
  48     uint8_t *out_bytes = out;
  49     size_t n;
  50
  51     while (nbytes) {
  52         if (pad_offset == ecb->block_size) {
  53             ecb->ecb(ecb_key, 1, ctr, pad);
  54             pad_offset = 0;
  55
  56             /* increment the big endian counter */
  57             inc_uint(ctr + ecb->block_size - counter_size, counter_size);
  58
  59             if (nbytes==0) break;
  60         }
  61
  62         n = CC_MIN(nbytes, ecb->block_size - pad_offset);
  63         cc_xor(n, out_bytes, in_bytes, pad + pad_offset);
  64         nbytes -= n;
  65         in_bytes += n;
  66         out_bytes += n;
  67         pad_offset += n;
  68     }
  69     CCMODE_CTR_KEY_PAD_OFFSET(key) = pad_offset;
  70
  71     return 0;
  72 }