base/md5.h

   1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef BASE_MD5_H_
   6 #define BASE_MD5_H_
   7
   8 #include "base/base_export.h"
   9 #include "base/string_piece.h"
  10
  11 namespace base {
  12
  13 // MD5 stands for Message Digest algorithm 5.
  14 // MD5 is a robust hash function, designed for cyptography, but often used
  15 // for file checksums.  The code is complex and slow, but has few
  16 // collisions.
  17 // See Also:
  18 //   http://en.wikipedia.org/wiki/MD5
  19
  20 // These functions perform MD5 operations. The simplest call is MD5Sum() to
  21 // generate the MD5 sum of the given data.
  22 //
  23 // You can also compute the MD5 sum of data incrementally by making multiple
  24 // calls to MD5Update():
  25 //   MD5Context ctx; // intermediate MD5 data: do not use
  26 //   MD5Init(&ctx);
  27 //   MD5Update(&ctx, data1, length1);
  28 //   MD5Update(&ctx, data2, length2);
  29 //   ...
  30 //
  31 //   MD5Digest digest; // the result of the computation
  32 //   MD5Final(&digest, &ctx);
  33 //
  34 // You can call MD5DigestToBase16() to generate a string of the digest.
  35
  36 // The output of an MD5 operation.
  37 struct MD5Digest {
  38   unsigned char a[16];
  39 };
  40
  41 // Used for storing intermediate data during an MD5 computation. Callers
  42 // should not access the data.
  43 typedef char MD5Context[88];
  44
  45 // Computes the MD5 sum of the given data buffer with the given length.
  46 // The given 'digest' structure will be filled with the result data.
  47 BASE_EXPORT void MD5Sum(const void* data, size_t length, MD5Digest* digest);
  48
  49 // Initializes the given MD5 context structure for subsequent calls to
  50 // MD5Update().
  51 BASE_EXPORT void MD5Init(MD5Context* context);
  52
  53 // For the given buffer of |data| as a StringPiece, updates the given MD5
  54 // context with the sum of the data. You can call this any number of times
  55 // during the computation, except that MD5Init() must have been called first.
  56 BASE_EXPORT void MD5Update(MD5Context* context, const StringPiece& data);
  57
  58 // Finalizes the MD5 operation and fills the buffer with the digest.
  59 BASE_EXPORT void MD5Final(MD5Digest* digest, MD5Context* context);
  60
  61 // Converts a digest into human-readable hexadecimal.
  62 BASE_EXPORT std::string MD5DigestToBase16(const MD5Digest& digest);
  63
  64 // Returns the MD5 (in hexadecimal) of a string.
  65 BASE_EXPORT std::string MD5String(const StringPiece& str);
  66
  67 }  // namespace base
  68
  69 #endif  // BASE_MD5_H_