Crypto++  8.8 Free C++ class library of cryptographic schemes
rw.h
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1 // rw.h - originally written and placed in the public domain by Wei Dai
2
3 /// \file rw.h
4 /// \brief Classes for Rabin-Williams signature scheme
5 /// \details The implementation provides Rabin-Williams signature schemes as defined in
6 /// IEEE P1363. It uses Bernstein's tweaked square roots in place of square roots to
7 /// speedup calculations.
8 /// \sa <A HREF="http://cr.yp.to/sigs/rwsota-20080131.pdf">RSA signatures and Rabinâ€“Williams
9 /// signatures: the state of the art (20080131)</A>, Section 6, <em>The tweaks e and f</em>.
10 /// \since Crypto++ 3.0
11
12 #ifndef CRYPTOPP_RW_H
13 #define CRYPTOPP_RW_H
14
15 #include "cryptlib.h"
16 #include "pubkey.h"
17 #include "integer.h"
18
19 NAMESPACE_BEGIN(CryptoPP)
20
21 /// \brief Rabin-Williams trapdoor function using the public key
22 /// \since Crypto++ 3.0, Tweaked roots using <em>e</em> and <em>f</em> since Crypto++ 5.6.4
23 class CRYPTOPP_DLL RWFunction : public TrapdoorFunction, public PublicKey
24 {
25  typedef RWFunction ThisClass;
26
27 public:
28
29  /// \brief Initialize a Rabin-Williams public key
30  /// \param n the modulus
31  void Initialize(const Integer &n)
32  {m_n = n;}
33
34  void BERDecode(BufferedTransformation &bt);
35  void DEREncode(BufferedTransformation &bt) const;
36
37  void Save(BufferedTransformation &bt) const
38  {DEREncode(bt);}
40  {BERDecode(bt);}
41
42  Integer ApplyFunction(const Integer &x) const;
43  Integer PreimageBound() const {return ++(m_n>>1);}
44  Integer ImageBound() const {return m_n;}
45
46  bool Validate(RandomNumberGenerator &rng, unsigned int level) const;
47  bool GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const;
48  void AssignFrom(const NameValuePairs &source);
49
50  const Integer& GetModulus() const {return m_n;}
51  void SetModulus(const Integer &n) {m_n = n;}
52
53 protected:
54  Integer m_n;
55 };
56
57 /// \brief Rabin-Williams trapdoor function using the private key
58 /// \since Crypto++ 3.0, Tweaked roots using <em>e</em> and <em>f</em> since Crypto++ 5.6.4
59 class CRYPTOPP_DLL InvertibleRWFunction : public RWFunction, public TrapdoorFunctionInverse, public PrivateKey
60 {
62
63 public:
64  /// \brief Construct an InvertibleRWFunction
65  InvertibleRWFunction() : m_precompute(false) {}
66
67  /// \brief Initialize a Rabin-Williams private key
68  /// \param n modulus
69  /// \param p first prime factor
70  /// \param q second prime factor
71  /// \param u q<sup>-1</sup> mod p
72  /// \details This Initialize() function overload initializes a private key from existing parameters.
73  void Initialize(const Integer &n, const Integer &p, const Integer &q, const Integer &u);
74
75  /// \brief Create a Rabin-Williams private key
76  /// \param rng a RandomNumberGenerator derived class
77  /// \param modulusBits the size of the modulus, in bits
78  /// \details This function overload of Initialize() creates a new private key because it
79  /// takes a RandomNumberGenerator() as a parameter. If you have an existing keypair,
80  /// then use one of the other Initialize() overloads.
81  void Initialize(RandomNumberGenerator &rng, unsigned int modulusBits)
82  {GenerateRandomWithKeySize(rng, modulusBits);}
83
84  void BERDecode(BufferedTransformation &bt);
85  void DEREncode(BufferedTransformation &bt) const;
86
87  void Save(BufferedTransformation &bt) const
88  {DEREncode(bt);}
90  {BERDecode(bt);}
91
93
94  // GeneratibleCryptoMaterial
95  bool Validate(RandomNumberGenerator &rng, unsigned int level) const;
96  bool GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const;
97  void AssignFrom(const NameValuePairs &source);
98  /*! parameters: (ModulusSize) */
100
101  const Integer& GetPrime1() const {return m_p;}
102  const Integer& GetPrime2() const {return m_q;}
103  const Integer& GetMultiplicativeInverseOfPrime2ModPrime1() const {return m_u;}
104
105  void SetPrime1(const Integer &p) {m_p = p;}
106  void SetPrime2(const Integer &q) {m_q = q;}
107  void SetMultiplicativeInverseOfPrime2ModPrime1(const Integer &u) {m_u = u;}
108
109  virtual bool SupportsPrecomputation() const {return true;}
110  virtual void Precompute(unsigned int unused = 0) {CRYPTOPP_UNUSED(unused); PrecomputeTweakedRoots();}
111  virtual void Precompute(unsigned int unused = 0) const {CRYPTOPP_UNUSED(unused); PrecomputeTweakedRoots();}
112
113  virtual void LoadPrecomputation(BufferedTransformation &storedPrecomputation);
114  virtual void SavePrecomputation(BufferedTransformation &storedPrecomputation) const;
115
116 protected:
117  void PrecomputeTweakedRoots() const;
118
119 protected:
120  Integer m_p, m_q, m_u;
121
122  mutable Integer m_pre_2_9p, m_pre_2_3q, m_pre_q_p;
123  mutable bool m_precompute;
124 };
125
126 /// \brief Rabin-Williams keys
127 /// \since Crypto++ 3.0
128 struct RW
129 {
130  CRYPTOPP_STATIC_CONSTEXPR const char* StaticAlgorithmName() {return "RW";}
131  typedef RWFunction PublicKey;
133 };
134
135 /// \brief Rabin-Williams signature scheme
136 /// \tparam STANDARD signature standard
137 /// \tparam H hash transformation
138 /// \since Crypto++ 3.0
139 template <class STANDARD, class H>
140 struct RWSS : public TF_SS<RW, STANDARD, H>
141 {
142 };
143
144 NAMESPACE_END
145
146 #endif
Interface for buffered transformations.
Definition: cryptlib.h:1657
virtual void Precompute(unsigned int precomputationStorage)
Perform precomputation.
Definition: cryptlib.h:2477
void GenerateRandomWithKeySize(RandomNumberGenerator &rng, unsigned int keySize)
Generate a random key or crypto parameters.
Multiple precision integer with arithmetic operations.
Definition: integer.h:50
Rabin-Williams trapdoor function using the private key.
Definition: rw.h:60
virtual void LoadPrecomputation(BufferedTransformation &storedPrecomputation)
Retrieve previously saved precomputation.
bool Validate(RandomNumberGenerator &rng, unsigned int level) const
Check this object for errors.
void Save(BufferedTransformation &bt) const
Saves a key to a BufferedTransformation.
Definition: rw.h:87
void AssignFrom(const NameValuePairs &source)
Assign values to this object.
Loads a key from a BufferedTransformation.
Definition: rw.h:89
void Initialize(const Integer &n, const Integer &p, const Integer &q, const Integer &u)
Initialize a Rabin-Williams private key.
void Initialize(RandomNumberGenerator &rng, unsigned int modulusBits)
Create a Rabin-Williams private key.
Definition: rw.h:81
virtual bool SupportsPrecomputation() const
Determines whether the object supports precomputation.
Definition: rw.h:109
virtual void SavePrecomputation(BufferedTransformation &storedPrecomputation) const
Save precomputation for later use.
bool GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const
Get a named value.
void GenerateRandom(RandomNumberGenerator &rng, const NameValuePairs &alg)
InvertibleRWFunction()
Construct an InvertibleRWFunction.
Definition: rw.h:65
virtual void Precompute(unsigned int unused=0)
Perform precomputation.
Definition: rw.h:110
Integer CalculateInverse(RandomNumberGenerator &rng, const Integer &x) const
Calculates the inverse of an element.
Interface for retrieving values given their names.
Definition: cryptlib.h:327
Interface for private keys.
Definition: cryptlib.h:2546
Interface for public keys.
Definition: cryptlib.h:2541
Rabin-Williams trapdoor function using the public key.
Definition: rw.h:24
Integer PreimageBound() const
Returns the maximum size of a message before the trapdoor function is applied.
Definition: rw.h:43
Integer ApplyFunction(const Integer &x) const
Applies the trapdoor.
Integer ImageBound() const
Returns the maximum size of a representation after the trapdoor function is applied.
Definition: rw.h:44
void Save(BufferedTransformation &bt) const
Saves a key to a BufferedTransformation.
Definition: rw.h:37
void Initialize(const Integer &n)
Initialize a Rabin-Williams public key.
Definition: rw.h:31
void AssignFrom(const NameValuePairs &source)
Assign values to this object.
bool GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const
Get a named value.
Loads a key from a BufferedTransformation.
Definition: rw.h:39
bool Validate(RandomNumberGenerator &rng, unsigned int level) const
Check this object for errors.
Interface for random number generators.
Definition: cryptlib.h:1440
Trapdoor Function (TF) Signature Scheme.
Definition: pubkey.h:2316
Applies the trapdoor function.
Definition: pubkey.h:126
Applies the inverse of the trapdoor function.
Definition: pubkey.h:179
Abstract base classes that provide a uniform interface to this library.
Multiple precision integer with arithmetic operations.
Crypto++ library namespace.
This file contains helper classes/functions for implementing public key algorithms.
Rabin-Williams keys.
Definition: rw.h:129
Rabin-Williams signature scheme.
Definition: rw.h:141