OSX/libsecurity_cryptkit/lib/HmacSha1Legacy.c

   1 /*
   2  * Copyright (c) 2000-2001,2011-2014 Apple Inc. All Rights Reserved.
   3  *
   4  * The contents of this file constitute Original Code as defined in and are
   5  * subject to the Apple Public Source License Version 1.2 (the 'License').
   6  * You may not use this file except in compliance with the License. Please obtain
   7  * a copy of the License at http://www.apple.com/publicsource and read it before
   8  * using this file.
   9  *
  10  * This Original Code and all software distributed under the License are
  11  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS
  12  * OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, INCLUDING WITHOUT
  13  * LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
  14  * PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. Please see the License for the
  15  * specific language governing rights and limitations under the License.
  16  */
  17
  18
  19 /*
  20         File:           HmacSha1Legacy.c
  21         Contains:       HMAC/SHA1, bug-for-bug compatible with BSAFE 4.0.
  22         Copyright (c) 2001,2011-2014 Apple Inc. All Rights Reserved.
  23 */
  24
  25 #include "ckconfig.h"
  26
  27 #if     CRYPTKIT_HMAC_LEGACY
  28
  29 #include "HmacSha1Legacy.h"
  30 #include "ckSHA1.h"
  31 #include <string.h>
  32 #include <stdlib.h>
  33 #include <Security/SecBase.h>
  34 #define kHMACSHA1DigestSize  20
  35
  36 /* XXX These should really be in ckSHA1.h */
  37 #define kSHA1DigestSize         20
  38 #define kSHA1BlockSize          64
  39
  40 /*
  41  * bug-for-bug compatible with BSAFE 4.0. See
  42  * BSafe/bsource/algs/ahchhmac.c.
  43  *
  44  * This implementation, and the BSAFE implementation it emulates, work fine
  45  * when calculating a MAC in a single update (init, update, final). They
  46  * generate nonconforming MACs when performing multiple updates because
  47  * the entire algorithm - both inner and outer digests - are performed
  48  * in the update() step. As a result, if one e.g. calculates a MAC of
  49  * a block of text with one update, and then calculates the MAC over the
  50  * same block of text via two updates, different results will obtain.ÊThe
  51  * incorrect result from the multiple-update scenario is repeatable if and
  52  * only if the same boundaries (same update sizes) are observed on each operation.
  53  *
  54  * Because all of the data to be MAC'd is in fact protected by both levels of
  55  * SHA1, and all of the key bits are used, this nonconforming implementation is
  56  * believed to be as strong, cryptographically, as a conforming SHA1HMAC
  57  * implementation.
  58  */
  59 struct hmacLegacyContext {
  60         sha1Obj sha1Context;
  61         UInt8   k_ipad[kSHA1BlockSize];
  62         UInt8   k_opad[kSHA1BlockSize];
  63 };
  64
  65 hmacLegacyContextRef hmacLegacyAlloc(void)
  66 {
  67         hmacLegacyContextRef hmac =
  68                 (hmacLegacyContextRef)malloc(sizeof(struct hmacLegacyContext));
  69         memset(hmac, 0, sizeof(struct hmacLegacyContext));
  70         return hmac;
  71 }
  72
  73 void hmacLegacyFree(
  74         hmacLegacyContextRef hmac)
  75 {
  76         if(hmac != NULL) {
  77                 if(hmac->sha1Context != NULL) {
  78                         sha1Free (hmac->sha1Context);
  79                 }
  80                 memset(hmac, 0, sizeof(struct hmacLegacyContext));
  81                 free(hmac);
  82         }
  83 }
  84
  85 /* reusable init */
  86 OSStatus hmacLegacyInit(
  87         hmacLegacyContextRef hmac,
  88         const void *keyPtr,
  89         UInt32 keyLen)
  90 {
  91         UInt8   *key;
  92         UInt32  byte;
  93
  94         if(hmac->sha1Context == NULL) {
  95                 hmac->sha1Context = sha1Alloc();
  96                 if(hmac->sha1Context == NULL) {
  97                         return errSecAllocate;
  98                 }
  99         }
 100         else {
 101                 sha1Reinit(hmac->sha1Context);
 102         }
 103         /* this implementation requires a 20-byte key */
 104         if (keyLen != kSHA1DigestSize) {
 105                 /* FIXME */
 106                 return errSecParam;
 107         }
 108         key = (UInt8*)keyPtr;
 109
 110         /* The HMAC_SHA_1 transform looks like:
 111            SHA1 (K XOR opad || SHA1 (K XOR ipad || text))
 112            Where K is a n byte key
 113            ipad is the byte 0x36 repeated 64 times.
 114            opad is the byte 0x5c repeated 64 times.
 115            text is the data being protected.
 116           */
 117         /* Copy the key into k_ipad and k_opad while doing the XOR. */
 118         for (byte = 0; byte < keyLen; byte++)
 119         {
 120                 hmac->k_ipad[byte] = key[byte] ^ 0x36;
 121                 hmac->k_opad[byte] = key[byte] ^ 0x5c;
 122         }
 123
 124         /* Fill the remainder of k_ipad and k_opad with 0 XORed with
 125          * appropriate value. */
 126         memset (hmac->k_ipad + keyLen, 0x36, kSHA1BlockSize - keyLen);
 127         memset (hmac->k_opad + keyLen, 0x5c, kSHA1BlockSize - keyLen);
 128
 129         /* remainder happens in update */
 130         return errSecSuccess;
 131 }
 132
 133 OSStatus hmacLegacyUpdate(
 134         hmacLegacyContextRef hmac,
 135         const void *textPtr,
 136         UInt32 textLen)
 137 {
 138         UInt8 innerDigest[kSHA1DigestSize];
 139
 140         /* compute SHA1(k_ipad || data) ==> innerDigest */
 141         sha1AddData (hmac->sha1Context, hmac->k_ipad, kSHA1BlockSize);
 142         sha1AddData (hmac->sha1Context, (UInt8*)textPtr, textLen);
 143         memcpy (innerDigest, sha1Digest(hmac->sha1Context), kSHA1DigestSize);
 144
 145         /* reset context (BSAFE does this implicitly in a final() call) */
 146         sha1Reinit(hmac->sha1Context);
 147
 148         /* compute SHA1(k_opad || innerDigest) */
 149         sha1AddData (hmac->sha1Context, hmac->k_opad, kSHA1BlockSize);
 150         sha1AddData (hmac->sha1Context, innerDigest, kSHA1DigestSize);
 151
 152         /* if there is another update coming, it gets added in to existing
 153          * context; if the next step is a final, the current digest state is used. */
 154         return errSecSuccess;
 155 }
 156
 157 OSStatus hmacLegacyFinal(
 158         hmacLegacyContextRef hmac,
 159         void *resultPtr)                // caller mallocs, must be HMACSHA1_OUT_SIZE bytes
 160 {
 161         memcpy (resultPtr, sha1Digest (hmac->sha1Context), kSHA1DigestSize);
 162         return errSecSuccess;
 163 }
 164
 165 #endif  /* CRYPTKIT_HMAC_LEGACY */