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
  55         enc = g_crypto_funcs->ccaes_xts_encrypt;
  56         dec = g_crypto_funcs->ccaes_xts_decrypt;
  57
  58         if (!enc || !dec) {
  59                 panic("%s: xts mode not registered? enc=%p, dec=%p\n", __FUNCTION__, enc, dec);
  60         }
  61
  62         /* Make sure the context size for the mode fits in the one we have */
  63         if ((enc->size > sizeof(xts->enc)) || (dec->size > sizeof(xts->dec))) {
  64                 panic("%s: inconsistent size for AES-XTS context", __FUNCTION__);
  65         }
  66
  67         int rc = enc->init(enc, xts->enc, keylen, key1, key2);
  68         rc |= dec->init(dec, xts->dec, keylen, key1, key2);
  69
  70         return rc;
  71 }
  72
  73 int
  74 xts_encrypt(const uint8_t *pt, unsigned long ptlen,
  75     uint8_t *ct,
  76     const uint8_t *iv,                     // this can be considered the sector IV for this use
  77     symmetric_xts *xts)
  78 {
  79         const struct ccmode_xts *xtsenc = g_crypto_funcs->ccaes_xts_encrypt;
  80         ccxts_tweak_decl(xtsenc->tweak_size, tweak);
  81
  82         if (ptlen % 16) {
  83                 panic("xts encrypt not a multiple of block size\n");
  84         }
  85
  86         int rc = xtsenc->set_tweak(xts->enc, tweak, iv);
  87         if (rc) {
  88                 return rc;
  89         }
  90
  91         xtsenc->xts(xts->enc, tweak, ptlen / 16, pt, ct);
  92         return 0;
  93 }
  94
  95 int
  96 xts_decrypt(const uint8_t *ct, unsigned long ptlen,
  97     uint8_t *pt,
  98     const uint8_t *iv,                             // this can be considered the sector IV for this use
  99     symmetric_xts *xts)
 100 {
 101         const struct ccmode_xts *xtsdec = g_crypto_funcs->ccaes_xts_decrypt;
 102         ccxts_tweak_decl(xtsdec->tweak_size, tweak);
 103
 104         if (ptlen % 16) {
 105                 panic("xts decrypt not a multiple of block size\n");
 106         }
 107
 108         int rc = xtsdec->set_tweak(xts->dec, tweak, iv);
 109         if (rc) {
 110                 return rc;
 111         }
 112
 113         xtsdec->xts(xts->dec, tweak, ptlen / 16, ct, pt);
 114         return 0;
 115 }
 116
 117 void
 118 xts_done(symmetric_xts *xts __unused)
 119 {
 120         cc_clear(sizeof(xts->enc), xts->enc);
 121         cc_clear(sizeof(xts->dec), xts->dec);
 122 }