Crypto++  8.8
Free C++ class library of cryptographic schemes
crc.h
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1 // crc.h - originally written and placed in the public domain by Wei Dai
2 
3 /// \file crc.h
4 /// \brief Classes for CRC-32 and CRC-32C checksum algorithm
5 
6 #ifndef CRYPTOPP_CRC32_H
7 #define CRYPTOPP_CRC32_H
8 
9 #include "cryptlib.h"
10 
11 NAMESPACE_BEGIN(CryptoPP)
12 
13 const word32 CRC32_NEGL = 0xffffffffL;
14 
15 #if (CRYPTOPP_LITTLE_ENDIAN)
16 #define CRC32_INDEX(c) (c & 0xff)
17 #define CRC32_SHIFTED(c) (c >> 8)
18 #else
19 #define CRC32_INDEX(c) (c >> 24)
20 #define CRC32_SHIFTED(c) (c << 8)
21 #endif
22 
23 /// \brief CRC-32 Checksum Calculation
24 /// \details Uses CRC polynomial 0xEDB88320
25 class CRC32 : public HashTransformation
26 {
27 public:
28  CRYPTOPP_CONSTANT(DIGESTSIZE = 4);
29  CRC32();
30  void Update(const byte *input, size_t length);
31  void TruncatedFinal(byte *hash, size_t size);
32  unsigned int DigestSize() const {return DIGESTSIZE;}
33  CRYPTOPP_STATIC_CONSTEXPR const char* StaticAlgorithmName() {return "CRC32";}
34  std::string AlgorithmName() const {return StaticAlgorithmName();}
35 
36  /// \brief Updates a CRC with additional input
37  /// \param b the additional input as a byte
38  void UpdateByte(byte b) {m_crc = m_tab[CRC32_INDEX(m_crc) ^ b] ^ CRC32_SHIFTED(m_crc);}
39 
40  /// \brief Retrieves the i-th byte of the CRC
41  /// \param i the additional input as a byte
42  /// \return the byte at the i-th position
43  byte GetCrcByte(size_t i) const {return reinterpret_cast<const byte *>(&m_crc)[i];}
44 
45  std::string AlgorithmProvider() const;
46 
47 protected:
48  void Reset() {m_crc = CRC32_NEGL;}
49 
50 private:
51  static const word32 m_tab[256];
52  word32 m_crc;
53 };
54 
55 /// \brief CRC-32C Checksum Calculation
56 /// \details Uses CRC polynomial 0x82F63B78
57 /// \since Crypto++ 5.6.4
58 class CRC32C : public HashTransformation
59 {
60 public:
61  CRYPTOPP_CONSTANT(DIGESTSIZE = 4);
62  CRC32C();
63  void Update(const byte *input, size_t length);
64  void TruncatedFinal(byte *hash, size_t size);
65  unsigned int DigestSize() const {return DIGESTSIZE;}
66  CRYPTOPP_STATIC_CONSTEXPR const char* StaticAlgorithmName() {return "CRC32C";}
67  std::string AlgorithmName() const {return StaticAlgorithmName();}
68 
69  /// \brief Updates a CRC with additional input
70  /// \param b the additional input as a byte
71  void UpdateByte(byte b) {m_crc = m_tab[CRC32_INDEX(m_crc) ^ b] ^ CRC32_SHIFTED(m_crc);}
72 
73  /// \brief Retrieves the i-th byte of the CRC
74  /// \param i the additional input as a byte
75  /// \return the byte at the i-th position
76  byte GetCrcByte(size_t i) const {return reinterpret_cast<const byte *>(&m_crc)[i];}
77 
78  std::string AlgorithmProvider() const;
79 
80 protected:
81  void Reset() {m_crc = CRC32_NEGL;}
82 
83 private:
84  static const word32 m_tab[256];
85  word32 m_crc;
86 };
87 
88 NAMESPACE_END
89 
90 #endif
CRC-32C Checksum Calculation.
Definition: crc.h:59
void TruncatedFinal(byte *hash, size_t size)
Computes the hash of the current message.
Definition: crc.cpp:356
std::string AlgorithmName() const
Provides the name of this algorithm.
Definition: crc.h:67
void UpdateByte(byte b)
Updates a CRC with additional input.
Definition: crc.h:71
byte GetCrcByte(size_t i) const
Retrieves the i-th byte of the CRC.
Definition: crc.h:76
unsigned int DigestSize() const
Provides the digest size of the hash.
Definition: crc.h:65
void Update(const byte *input, size_t length)
Updates a hash with additional input.
Definition: crc.cpp:319
std::string AlgorithmProvider() const
Retrieve the provider of this algorithm.
Definition: crc.cpp:301
CRC-32 Checksum Calculation.
Definition: crc.h:26
unsigned int DigestSize() const
Provides the digest size of the hash.
Definition: crc.h:32
byte GetCrcByte(size_t i) const
Retrieves the i-th byte of the CRC.
Definition: crc.h:43
std::string AlgorithmName() const
Provides the name of this algorithm.
Definition: crc.h:34
void TruncatedFinal(byte *hash, size_t size)
Computes the hash of the current message.
Definition: crc.cpp:178
void Update(const byte *input, size_t length)
Updates a hash with additional input.
Definition: crc.cpp:147
std::string AlgorithmProvider() const
Retrieve the provider of this algorithm.
Definition: crc.cpp:133
void UpdateByte(byte b)
Updates a CRC with additional input.
Definition: crc.h:38
Interface for hash functions and data processing part of MACs.
Definition: cryptlib.h:1118
unsigned int word32
32-bit unsigned datatype
Definition: config_int.h:72
Abstract base classes that provide a uniform interface to this library.
Crypto++ library namespace.