OSX/libsecurity_utilities/lib/hashing.h

   1 /*
   2  * Copyright (c) 2005-2012 Apple Inc. All Rights Reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
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   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
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  18  * Please see the License for the specific language governing rights and
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  22  */
  23
  24 //
  25 // Fast hash support
  26 //
  27 #ifndef _H_HASHING
  28 #define _H_HASHING
  29
  30 #include <CommonCrypto/CommonDigest.h>
  31 #include <cstring>
  32 #include <memory>
  33 #include <sys/types.h>
  34 #include <security_utilities/refcount.h>
  35 #include <CommonCrypto/CommonDigestSPI.h>       // SPI slated to become API
  36
  37 namespace Security {
  38
  39
  40 //
  41 // An unconditional base class for all hash objects.
  42 // Not much in here; there's no point in declaring one yourself.
  43 //
  44 class Hashing {
  45 public:
  46         typedef unsigned char Byte;
  47 };
  48
  49
  50 //
  51 // Common prefix for all static hashers.
  52 // There's no magic here; we're just setting up a regular framework for duck typing.
  53 //
  54 // If you write template code based on "any static hasher", you can directly tap here
  55 // (and learn the actual hash in use through the match on _HashType). But note that
  56 // a DynamicHash is not a subclass of Hash.
  57 //
  58 template <uint32_t _size, class _HashType>
  59 class Hash : public Hashing {
  60         _HashType &_self() { return static_cast<_HashType &>(*this); }  // "my real type"
  61 public:
  62         static const size_t digestLength = _size;                       // how many bytes in my digest?
  63         typedef Byte Digest[_size];                                                     // my digest as a Byte array
  64         struct SDigest {                                                                        // my digest as a struct
  65                 Digest data;
  66
  67                 SDigest() { }
  68                 SDigest(const Byte *source) { ::memcpy(data, source, digestLength); }
  69                 friend bool operator < (const SDigest &x, const SDigest &y)     // usable as collection key
  70                         { return ::memcmp(x.data, y.data, digestLength) < 0; }
  71                 bool operator == (const SDigest &other) const
  72                         { return ::memcmp(this->data, other.data, digestLength) == 0; }
  73                 bool operator != (const SDigest &other) const
  74                         { return ::memcmp(this->data, other.data, digestLength) != 0; }
  75                 bool operator == (const Byte *other) const
  76                         { return ::memcmp(this->data, other, digestLength) == 0; }
  77                 bool operator != (const Byte *other) const
  78                         { return ::memcmp(this->data, other, digestLength) != 0; }
  79         };
  80
  81         void operator () (const void *data, size_t length)      // just an alias for update()
  82                 { _self().update(data, length); }
  83
  84         void finish(SDigest &digest)
  85                 { _self().finish(digest.data); }
  86
  87         bool verify(const Byte *digest)
  88                 { Digest d; _self().finish(d); return memcmp(d, digest, digestLength) == 0; }
  89 };
  90
  91
  92 //
  93 // A dynamic switch for digest generators.
  94 // This isn't a subclass of Hash (which is static-fast), but it's duck-typed to it.
  95 // Note that digestLength is a function here, not a constant. Obviously.
  96 //
  97 class DynamicHash : public RefCount, public Hashing {
  98 public:
  99         virtual ~DynamicHash();
 100
 101         virtual size_t digestLength() const = 0;
 102         virtual void update(const void *data, size_t length) = 0;
 103         template<typename _Dataoid>
 104         void update(const _Dataoid &doid) { this->update(doid.data(), doid.length()); }
 105         virtual void finish(Byte *digest) = 0;
 106
 107         void operator () (const void *data, size_t length)
 108                 { return this->update(data, length); }
 109
 110         bool verify(const Byte *digest)
 111                 { Byte d[this->digestLength()]; this->finish(d); return memcmp(d, digest, this->digestLength()) == 0; }
 112 };
 113
 114
 115 //
 116 // Make a DynamicHash from a CommonCrypto hash algorithm identifier
 117 //
 118 class CCHashInstance : public DynamicHash {
 119 public:
 120         CCHashInstance(CCDigestAlg alg, size_t truncate = 0);
 121         ~CCHashInstance()
 122                 { CCDigestDestroy(mDigest); }
 123
 124         size_t digestLength() const
 125                 { return mTruncate ? mTruncate : CCDigestOutputSize(mDigest); }
 126         void update(const void *data, size_t length)
 127                 { CCDigestUpdate(mDigest, data, length); }
 128         void finish(unsigned char *digest);
 129
 130 private:
 131         CCDigestRef mDigest;
 132         size_t mTruncate;
 133 };
 134
 135
 136 //
 137 // A shorthand for holding a DynamicHash subclass we got from some
 138 // object out there by asking nicely (by default, calling its getHash() method).
 139 //
 140 template <class _Giver, DynamicHash *(_Giver::*_fetcher)() const = &_Giver::getHash>
 141 class MakeHash : public RefPointer<DynamicHash> {
 142 public:
 143         MakeHash(const _Giver *giver) : RefPointer<DynamicHash>((giver->*_fetcher)()) { }
 144
 145         operator DynamicHash *() const { return this->get(); }
 146 };
 147
 148
 149 //
 150 // A concrete SHA1 class, used in a very many different places.
 151 // Note that its digestLength is a constant (not a function).
 152 //
 153 class SHA1 : public CC_SHA1_CTX, public Hash<CC_SHA1_DIGEST_LENGTH, SHA1>       {
 154 public:
 155         SHA1() { CC_SHA1_Init(this); }
 156         void update(const void *data, size_t length)
 157                 { CC_SHA1_Update(this, data, (CC_LONG)length); }
 158         void finish(Byte *digest) { CC_SHA1_Final(digest, this); }
 159         using Hash<CC_SHA1_DIGEST_LENGTH, SHA1>::finish;
 160 };
 161
 162
 163 }       // Security
 164
 165 #endif //_H_HASHING