libkern/crypto/corecrypto_aesxts.c

   1 /*
   2  * Copyright (c) 2012 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28
  29 #include <libkern/crypto/crypto_internal.h>
  30 #include <libkern/libkern.h>
  31 #include <libkern/crypto/aesxts.h>
  32 #include <corecrypto/ccmode.h>
  33 #include <corecrypto/ccpad.h>
  34 #include <kern/debug.h>
  35
  36 /*
  37  * These are the interfaces required for XTS-AES support
  38  */
  39
  40 uint32_t
  41 xts_start(uint32_t cipher __unused, // ignored - we're doing this for xts-aes only
  42                   const uint8_t *IV __unused, // ignored
  43                   const uint8_t *key1, int keylen,
  44                   const uint8_t *key2, int tweaklen __unused, // both keys are the same size for xts
  45                   uint32_t num_rounds __unused, // ignored
  46                   uint32_t options __unused,    // ignored
  47                   symmetric_xts *xts)
  48 {
  49                 const struct ccmode_xts *enc, *dec;
  50
  51                 if(!g_crypto_funcs)
  52                         panic("%s: corecrypto not registered!\n", __FUNCTION__);
  53
  54                 enc = g_crypto_funcs->ccaes_xts_encrypt;
  55                 dec = g_crypto_funcs->ccaes_xts_decrypt;
  56
  57                 if(!enc && !dec)
  58                         panic("%s: xts mode not registered? enc=%p, dec=%p\n", __FUNCTION__, enc, dec);
  59
  60                 /* Make sure the context size for the mode fits in the one we have */
  61                 if((enc->size>sizeof(xts->enc)) || (dec->size>sizeof(xts->dec)))
  62                         panic("%s: inconsistent size for AES-XTS context", __FUNCTION__);
  63
  64                 enc->init(enc, xts->enc, keylen, key1, key2);
  65                 dec->init(dec, xts->dec, keylen, key1, key2);
  66
  67                 return 0; //never fails
  68 }
  69
  70 int xts_encrypt(const uint8_t *pt, unsigned long ptlen,
  71                         uint8_t *ct,
  72                         const uint8_t *iv, // this can be considered the sector IV for this use
  73                         symmetric_xts *xts)
  74 {
  75         const struct ccmode_xts *xtsenc = g_crypto_funcs->ccaes_xts_encrypt;
  76         ccxts_tweak_decl(xtsenc->tweak_size, tweak);
  77
  78         if(ptlen%16) panic("xts encrypt not a multiple of block size\n");
  79
  80         xtsenc->set_tweak(xts->enc, tweak, iv);
  81         xtsenc->xts(xts->enc, tweak, ptlen/16, pt, ct);
  82
  83         return 0; //never fails
  84 }
  85
  86 int xts_decrypt(const uint8_t *ct, unsigned long ptlen,
  87                         uint8_t *pt,
  88                                 const uint8_t *iv, // this can be considered the sector IV for this use
  89                         symmetric_xts *xts)
  90 {
  91         const struct ccmode_xts *xtsdec = g_crypto_funcs->ccaes_xts_decrypt;
  92         ccxts_tweak_decl(xtsdec->tweak_size, tweak);
  93
  94         if(ptlen%16) panic("xts decrypt not a multiple of block size\n");
  95
  96         xtsdec->set_tweak(xts->dec, tweak, iv);
  97         xtsdec->xts(xts->dec, tweak, ptlen/16, ct, pt);
  98
  99         return 0; //never fails
 100 }
 101
 102 void xts_done(symmetric_xts *xts __unused)
 103 {
 104
 105 }