Crypto++  8.8
Free C++ class library of cryptographic schemes
blumshub.h
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1 // blumshub.h - originally written and placed in the public domain by Wei Dai
2 
3 /// \file blumshub.h
4 /// \brief Classes for Blum Blum Shub generator
5 
6 #ifndef CRYPTOPP_BLUMSHUB_H
7 #define CRYPTOPP_BLUMSHUB_H
8 
9 #include "cryptlib.h"
10 #include "modarith.h"
11 #include "integer.h"
12 
13 NAMESPACE_BEGIN(CryptoPP)
14 
15 /// \brief BlumBlumShub without factorization of the modulus
16 /// \details You should reseed the generator after a fork() to avoid multiple generators
17 /// with the same internal state.
20 {
21 public:
22  virtual ~PublicBlumBlumShub() {}
23 
24  /// \brief Construct a PublicBlumBlumShub
25  /// \param n the modulus
26  /// \param seed the seed for the generator
27  /// \details seed is the secret key and should be about as large as n.
28  PublicBlumBlumShub(const Integer &n, const Integer &seed);
29 
30  unsigned int GenerateBit();
31  byte GenerateByte();
32  void GenerateBlock(byte *output, size_t size);
33  void ProcessData(byte *outString, const byte *inString, size_t length);
34 
35  bool IsSelfInverting() const {return true;}
36  bool IsForwardTransformation() const {return true;}
37 
38 protected:
39  ModularArithmetic modn;
40  Integer current;
41  word maxBits, bitsLeft;
42 };
43 
44 /// \brief BlumBlumShub with factorization of the modulus
45 /// \details You should reseed the generator after a fork() to avoid multiple generators
46 /// with the same internal state.
48 {
49 public:
50  virtual ~BlumBlumShub() {}
51 
52  /// \brief Construct a BlumBlumShub
53  /// \param p the first prime factor
54  /// \param q the second prime factor
55  /// \param seed the seed for the generator
56  /// \details Esure p and q are both primes congruent to 3 mod 4 and at least 512 bits long.
57  /// seed is the secret key and should be about as large as p*q.
58  BlumBlumShub(const Integer &p, const Integer &q, const Integer &seed);
59 
60  bool IsRandomAccess() const {return true;}
61  void Seek(lword index);
62 
63 protected:
64  const Integer p, q;
65  const Integer x0;
66 };
67 
68 NAMESPACE_END
69 
70 #endif
BlumBlumShub with factorization of the modulus.
Definition: blumshub.h:48
BlumBlumShub(const Integer &p, const Integer &q, const Integer &seed)
Construct a BlumBlumShub.
Definition: blumshub.cpp:48
bool IsRandomAccess() const
Determines whether the cipher supports random access.
Definition: blumshub.h:60
void Seek(lword index)
Seek to an absolute position.
Definition: blumshub.cpp:55
Multiple precision integer with arithmetic operations.
Definition: integer.h:50
Ring of congruence classes modulo n.
Definition: modarith.h:44
BlumBlumShub without factorization of the modulus.
Definition: blumshub.h:20
bool IsForwardTransformation() const
Determines if the cipher is being operated in its forward direction.
Definition: blumshub.h:36
bool IsSelfInverting() const
Determines whether the cipher is self-inverting.
Definition: blumshub.h:35
Interface for random number generators.
Definition: cryptlib.h:1440
Interface for the data processing portion of stream ciphers.
Definition: cryptlib.h:951
word64 word
Full word used for multiprecision integer arithmetic.
Definition: config_int.h:192
word64 lword
Large word type.
Definition: config_int.h:168
Abstract base classes that provide a uniform interface to this library.
Multiple precision integer with arithmetic operations.
Class file for performing modular arithmetic.
Crypto++ library namespace.