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/strings/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 // MD5IntermediateFinal() generates a digest without finalizing the MD5 62 // operation. Can be used to generate digests for the input seen thus far, 63 // without affecting the digest generated for the entire input. 64 BASE_EXPORT void MD5IntermediateFinal(MD5Digest* digest, 65 const MD5Context* context); 66 67 // Converts a digest into human-readable hexadecimal. 68 BASE_EXPORT std::string MD5DigestToBase16(const MD5Digest& digest); 69 70 // Returns the MD5 (in hexadecimal) of a string. 71 BASE_EXPORT std::string MD5String(const StringPiece& str); 72 73 } // namespace base 74 75 #endif // BASE_MD5_H_ 76
