Security/libsecurity_utilities/lib/hashing.h

   1 /*
   2  * Copyright (c) 2005-2012 Apple Inc. All Rights Reserved.
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  10  * http://www.opensource.apple.com/apsl/ and read it before using this
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  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 <CommonCrypto/CommonDigestSPI.h>       // SPI slated to become API
  35
  36 namespace Security {
  37
  38
  39 //
  40 // An unconditional base class for all hash objects.
  41 // Not much in here; there's no point in declaring one yourself.
  42 //
  43 class Hashing {
  44 public:
  45         typedef unsigned char Byte;
  46 };
  47
  48
  49 //
  50 // Common prefix for all static hashers.
  51 // There's no magic here; we're just setting up a regular framework for duck typing.
  52 //
  53 // If you write template code based on "any static hasher", you can directly tap here
  54 // (and learn the actual hash in use through the match on _HashType). But note that
  55 // a DynamicHash is not a subclass of Hash, though a DynamicHashInstance will be, duck-like.
  56 //
  57 template <uint32_t _size, class _HashType>
  58 class Hash : public Hashing {
  59         _HashType &_self() { return static_cast<_HashType &>(*this); }  // "my real type"
  60 public:
  61         static const size_t digestLength = _size;                       // how many bytes in my digest?
  62         typedef Byte Digest[_size];                                                     // my digest as a Byte array
  63         struct SDigest {                                                                        // my digest as a struct
  64                 Digest data;
  65
  66                 SDigest() { }
  67                 SDigest(const Byte *source) { ::memcpy(data, source, digestLength); }
  68                 friend bool operator < (const SDigest &x, const SDigest &y)     // usable as collection key
  69                         { return ::memcmp(x.data, y.data, digestLength) < 0; }
  70                 bool operator == (const SDigest &other) const
  71                         { return ::memcmp(this->data, other.data, digestLength) == 0; }
  72                 bool operator != (const SDigest &other) const
  73                         { return ::memcmp(this->data, other.data, digestLength) != 0; }
  74                 bool operator == (const Byte *other) const
  75                         { return ::memcmp(this->data, other, digestLength) == 0; }
  76                 bool operator != (const Byte *other) const
  77                         { return ::memcmp(this->data, other, digestLength) != 0; }
  78         };
  79
  80         void operator () (const void *data, size_t length)      // just an alias for update()
  81                 { _self().update(data, length); }
  82
  83         void finish(SDigest &digest)
  84                 { _self().finish(digest.data); }
  85
  86         bool verify(const Byte *digest)
  87                 { Digest d; _self().finish(d); return memcmp(d, digest, digestLength) == 0; }
  88 };
  89
  90
  91 //
  92 // A dynamic switch for digest generators.
  93 // This isn't a subclass of Hash (which is static-fast), but it's duck-typed to it.
  94 // Note that digestLength is a function here, not a constant. Obviously.
  95 //
  96 class DynamicHash : public Hashing {
  97 public:
  98         virtual ~DynamicHash();
  99
 100         virtual size_t digestLength() const = 0;
 101         virtual void update(const void *data, size_t length) = 0;
 102         virtual void finish(Byte *digest) = 0;
 103
 104         void operator () (const void *data, size_t length)
 105                 { return this->update(data, length); }
 106
 107         bool verify(const Byte *digest)
 108                 { Byte d[this->digestLength()]; this->finish(d); return memcmp(d, digest, this->digestLength()) == 0; }
 109 };
 110
 111
 112 //
 113 // Make a DynamicHash from a static Hash class.
 114 //
 115 template <class _HashType>
 116 class DynamicHashInstance : public DynamicHash, public _HashType {
 117 public:
 118         // (wish we had C++0x already...)
 119         DynamicHashInstance() { }
 120         template <class Arg1>
 121         DynamicHashInstance(const Arg1 &arg1) : _HashType(arg1) { }
 122         template <class Arg1, class Arg2>
 123         DynamicHashInstance(const Arg1 &arg1, const Arg2 &arg2) : _HashType(arg1, arg2) { }
 124         template <class Arg1, class Arg2, class Arg3>
 125         DynamicHashInstance(const Arg1 &arg1, const Arg2 &arg2, const Arg3 &arg3) : _HashType(arg1, arg2, arg3) { }
 126
 127         size_t digestLength() const
 128                 { return _HashType::digestLength; }
 129         void update(const void *data, size_t length)
 130                 { return _HashType::update(data, length); }
 131         void finish(unsigned char *digest)
 132                 { return _HashType::finish(digest); }
 133 };
 134
 135
 136 //
 137 // Make a DynamicHash from a CommonCrypto hash algorithm identifier
 138 //
 139 class CCHashInstance : public DynamicHash {
 140 public:
 141         CCHashInstance(CCDigestAlg alg);
 142         ~CCHashInstance()
 143                 { CCDigestDestroy(mDigest); }
 144
 145         size_t digestLength() const
 146                 { return CCDigestOutputSize(mDigest); }
 147         void update(const void *data, size_t length)
 148                 { CCDigestUpdate(mDigest, data, length); }
 149         void finish(unsigned char *digest)
 150                 { CCDigestFinal(mDigest, digest); }
 151
 152 private:
 153         CCDigestRef mDigest;
 154 };
 155
 156
 157 //
 158 // A shorthand for holding a DynamicHash subclass we got from some
 159 // object out there by asking nicely (by default, calling its getHash() method).
 160 //
 161 template <class _Giver, DynamicHash *(_Giver::*_fetcher)() const = &_Giver::getHash>
 162 class MakeHash : public std::auto_ptr<DynamicHash> {
 163 public:
 164         MakeHash(const _Giver *giver) : std::auto_ptr<DynamicHash>((giver->*_fetcher)()) { }
 165
 166         operator DynamicHash *() const { return this->get(); }
 167 };
 168
 169
 170 //
 171 // A concrete SHA1 class, used in a very many different places.
 172 // Note that its digestLength is a constant (not a function).
 173 //
 174 class SHA1 : public CC_SHA1_CTX, public Hash<CC_SHA1_DIGEST_LENGTH, SHA1>       {
 175 public:
 176         SHA1() { CC_SHA1_Init(this); }
 177         void update(const void *data, size_t length)
 178                 { CC_SHA1_Update(this, data, (CC_LONG)length); }
 179         void finish(Byte *digest) { CC_SHA1_Final(digest, this); }
 180         using Hash<CC_SHA1_DIGEST_LENGTH, SHA1>::finish;
 181 };
 182
 183
 184 }       // Security
 185
 186 #endif //_H_HASHING