Crypto++  8.6
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  void UpdateByte(byte b) {m_crc = m_tab[CRC32_INDEX(m_crc) ^ b] ^ CRC32_SHIFTED(m_crc);}
37  byte GetCrcByte(size_t i) const {return reinterpret_cast<const byte *>(&m_crc)[i];}
38 
39  std::string AlgorithmProvider() const;
40 
41 protected:
42  void Reset() {m_crc = CRC32_NEGL;}
43 
44 private:
45  static const word32 m_tab[256];
46  word32 m_crc;
47 };
48 
49 /// \brief CRC-32C Checksum Calculation
50 /// \details Uses CRC polynomial 0x82F63B78
51 /// \since Crypto++ 5.6.4
52 class CRC32C : public HashTransformation
53 {
54 public:
55  CRYPTOPP_CONSTANT(DIGESTSIZE = 4);
56  CRC32C();
57  void Update(const byte *input, size_t length);
58  void TruncatedFinal(byte *hash, size_t size);
59  unsigned int DigestSize() const {return DIGESTSIZE;}
60  CRYPTOPP_STATIC_CONSTEXPR const char* StaticAlgorithmName() {return "CRC32C";}
61  std::string AlgorithmName() const {return StaticAlgorithmName();}
62 
63  void UpdateByte(byte b) {m_crc = m_tab[CRC32_INDEX(m_crc) ^ b] ^ CRC32_SHIFTED(m_crc);}
64  byte GetCrcByte(size_t i) const {return reinterpret_cast<const byte *>(&m_crc)[i];}
65 
66  std::string AlgorithmProvider() const;
67 
68 protected:
69  void Reset() {m_crc = CRC32_NEGL;}
70 
71 private:
72  static const word32 m_tab[256];
73  word32 m_crc;
74 };
75 
76 NAMESPACE_END
77 
78 #endif
CRC32C::AlgorithmProvider
std::string AlgorithmProvider() const
Retrieve the provider of this algorithm.
Definition: crc.cpp:301
HashTransformation
Interface for hash functions and data processing part of MACs.
Definition: cryptlib.h:1112
CRC32C::AlgorithmName
std::string AlgorithmName() const
Provides the name of this algorithm.
Definition: crc.h:61
word32
unsigned int word32
32-bit unsigned datatype
Definition: config_int.h:62
CRC32C::Update
void Update(const byte *input, size_t length)
Updates a hash with additional input.
Definition: crc.cpp:319
CRC32C
CRC-32C Checksum Calculation.
Definition: crc.h:52
CRC32::AlgorithmName
std::string AlgorithmName() const
Provides the name of this algorithm.
Definition: crc.h:34
CRC32
CRC-32 Checksum Calculation.
Definition: crc.h:25
CRC32::Update
void Update(const byte *input, size_t length)
Updates a hash with additional input.
Definition: crc.cpp:147
CRC32::TruncatedFinal
void TruncatedFinal(byte *hash, size_t size)
Computes the hash of the current message.
Definition: crc.cpp:178
CRC32::AlgorithmProvider
std::string AlgorithmProvider() const
Retrieve the provider of this algorithm.
Definition: crc.cpp:133
CryptoPP
Crypto++ library namespace.
CRC32C::DigestSize
unsigned int DigestSize() const
Provides the digest size of the hash.
Definition: crc.h:59
CRC32C::TruncatedFinal
void TruncatedFinal(byte *hash, size_t size)
Computes the hash of the current message.
Definition: crc.cpp:356
cryptlib.h
Abstract base classes that provide a uniform interface to this library.
CRC32::DigestSize
unsigned int DigestSize() const
Provides the digest size of the hash.
Definition: crc.h:32