md5.h revision ddb351dbec246cf1fab5ec20d2d5520909041de1 
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#pragma once
8
9#include <string>
10
11#include "base/base_api.h"
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
37typedef struct MD5Digest_struct {
38  unsigned char a[16];
39} MD5Digest;
40
41// Used for storing intermediate data during an MD5 computation. Callers
42// should not access the data.
43typedef 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.
47BASE_API void MD5Sum(const void* data, size_t length, MD5Digest* digest);
48
49// Initializes the given MD5 context structure for subsequent calls to
50// MD5Update().
51BASE_API void MD5Init(MD5Context* context);
52
53// For the given buffer of data, updates the given MD5 context with the sum of
54// the data. You can call this any number of times during the computation,
55// except that MD5Init() must have been called first.
56BASE_API void MD5Update(MD5Context* context, const void* buf, size_t len);
57
58// Finalizes the MD5 operation and fills the buffer with the digest.
59BASE_API void MD5Final(MD5Digest* digest, MD5Context* pCtx);
60
61// Converts a digest into human-readable hexadecimal.
62BASE_API std::string MD5DigestToBase16(const MD5Digest& digest);
63
64// Returns the MD5 (in hexadecimal) of a string.
65BASE_API std::string MD5String(const std::string& str);
66
67#endif  // BASE_MD5_H_
68
69