base/md5.h

// Copyright (c) 2006-2009 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_MD5_H_
#define BASE_MD5_H_
#pragma once

#include <string>

// MD5 stands for Message Digest algorithm 5.
// MD5 is a robust hash function, designed for cyptography, but often used
// for file checksums.  The code is complex and slow, but has few
// collisions.
// See Also:
//   http://en.wikipedia.org/wiki/MD5

// These functions perform MD5 operations. The simplest call is MD5Sum() to
// generate the MD5 sum of the given data.
//
// You can also compute the MD5 sum of data incrementally by making multiple
// calls to MD5Update():
//   MD5Context ctx; // intermediate MD5 data: do not use
//   MD5Init(&ctx);
//   MD5Update(&ctx, data1, length1);
//   MD5Update(&ctx, data2, length2);
//   ...
//
//   MD5Digest digest; // the result of the computation
//   MD5Final(&digest, &ctx);
//
// You can call MD5DigestToBase16() to generate a string of the digest.

// The output of an MD5 operation
typedef struct MD5Digest_struct {
  unsigned char a[16];
} MD5Digest;

// Used for storing intermediate data during an MD5 computation. Callers
// should not access the data.
typedef char MD5Context[88];

// Computes the MD5 sum of the given data buffer with the given length.
// The given 'digest' structure will be filled with the result data.
void MD5Sum(const void* data, size_t length, MD5Digest* digest);

// Initializes the given MD5 context structure for subsequent calls to
// MD5Update().
void MD5Init(MD5Context* context);

// For the given buffer of data, updates the given MD5 context with the sum of
// the data. You can call this any number of times during the computation,
// except that MD5Init() must have been called first.
void MD5Update(MD5Context* context, const void* buf, size_t len);

// Finalizes the MD5 operation and fills the buffer with the digest.
void MD5Final(MD5Digest* digest, MD5Context* pCtx);

// Converts a digest into human-readable hexadecimal.
std::string MD5DigestToBase16(const MD5Digest& digest);

// Returns the MD5 (in hexadecimal) of a string.
std::string MD5String(const std::string& str);

#endif  // BASE_MD5_H_