Crypto++  5.6.5
Free C++ class library of cryptographic schemes
rw.h
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1 // rw.h - 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 Rabin–Williams
9 //! signatures: the state of the art (20080131)</A>, Section 6, <em>The tweaks e and f</em>.
10 
11 #ifndef CRYPTOPP_RW_H
12 #define CRYPTOPP_RW_H
13 
14 #include "cryptlib.h"
15 #include "pubkey.h"
16 #include "integer.h"
17 
18 NAMESPACE_BEGIN(CryptoPP)
19 
20 //! \class RWFunction
21 //! \brief Rabin-Williams trapdoor function using the public key
22 //! \since Crypto++ 2.0, 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 //! \class InvertibleRWFunction
58 //! \brief Rabin-Williams trapdoor function using the private key
59 //! \since Crypto++ 2.0, Tweaked roots using <em>e</em> and <em>f</em> since Crypto++ 5.6.4
60 class CRYPTOPP_DLL InvertibleRWFunction : public RWFunction, public TrapdoorFunctionInverse, public PrivateKey
61 {
63 
64 public:
65  //! \brief Construct an InvertibleRWFunction
66  InvertibleRWFunction() : m_precompute(false) {}
67 
68  //! \brief Initialize a Rabin-Williams private key
69  //! \param n modulus
70  //! \param p first prime factor
71  //! \param q second prime factor
72  //! \param u q<sup>-1</sup> mod p
73  //! \details This Initialize() function overload initializes a private key from existing parameters.
74  void Initialize(const Integer &n, const Integer &p, const Integer &q, const Integer &u);
75 
76  //! \brief Create a Rabin-Williams private key
77  //! \param rng a RandomNumberGenerator derived class
78  //! \param modulusBits the size of the modulus, in bits
79  //! \details This function overload of Initialize() creates a new private key because it
80  //! takes a RandomNumberGenerator() as a parameter. If you have an existing keypair,
81  //! then use one of the other Initialize() overloads.
82  void Initialize(RandomNumberGenerator &rng, unsigned int modulusBits)
83  {GenerateRandomWithKeySize(rng, modulusBits);}
84 
85  void BERDecode(BufferedTransformation &bt);
86  void DEREncode(BufferedTransformation &bt) const;
87 
88  void Save(BufferedTransformation &bt) const
89  {DEREncode(bt);}
91  {BERDecode(bt);}
92 
94 
95  // GeneratibleCryptoMaterial
96  bool Validate(RandomNumberGenerator &rng, unsigned int level) const;
97  bool GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const;
98  void AssignFrom(const NameValuePairs &source);
99  /*! parameters: (ModulusSize) */
100  void GenerateRandom(RandomNumberGenerator &rng, const NameValuePairs &alg);
101 
102  const Integer& GetPrime1() const {return m_p;}
103  const Integer& GetPrime2() const {return m_q;}
104  const Integer& GetMultiplicativeInverseOfPrime2ModPrime1() const {return m_u;}
105 
106  void SetPrime1(const Integer &p) {m_p = p;}
107  void SetPrime2(const Integer &q) {m_q = q;}
108  void SetMultiplicativeInverseOfPrime2ModPrime1(const Integer &u) {m_u = u;}
109 
110  virtual bool SupportsPrecomputation() const {return true;}
111  virtual void Precompute(unsigned int unused = 0) {CRYPTOPP_UNUSED(unused); PrecomputeTweakedRoots();}
112  virtual void Precompute(unsigned int unused = 0) const {CRYPTOPP_UNUSED(unused); PrecomputeTweakedRoots();}
113 
114  virtual void LoadPrecomputation(BufferedTransformation &storedPrecomputation);
115  virtual void SavePrecomputation(BufferedTransformation &storedPrecomputation) const;
116 
117 protected:
118  void PrecomputeTweakedRoots() const;
119 
120 protected:
121  Integer m_p, m_q, m_u;
122 
123  mutable Integer m_pre_2_9p, m_pre_2_3q, m_pre_q_p;
124  mutable bool m_precompute;
125 };
126 
127 //! \brief Rabin-Williams keys
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 template <class STANDARD, class H>
139 struct RWSS : public TF_SS<RW, STANDARD, H>
140 {
141 };
142 
143 NAMESPACE_END
144 
145 #endif
virtual void AssignFrom(const NameValuePairs &source)=0
Assign values to this object.
virtual void Precompute(unsigned int precomputationStorage)
Perform precomputation.
Definition: cryptlib.h:2125
Rabin-Williams trapdoor function using the private key.
Definition: rw.h:60
virtual void SavePrecomputation(BufferedTransformation &storedPrecomputation) const
Save precomputation for later use.
Definition: cryptlib.h:2140
This file contains helper classes/functions for implementing public key algorithms.
void Load(BufferedTransformation &bt)
Loads a key from a BufferedTransformation.
Definition: rw.h:39
Abstract base classes that provide a uniform interface to this library.
virtual bool GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const =0
Get a named value.
Interface for random number generators.
Definition: cryptlib.h:1188
Integer ImageBound() const
Returns the maximum size of a message after the trapdoor function is applied.
Definition: rw.h:44
Interface for buffered transformations.
Definition: cryptlib.h:1352
virtual Integer CalculateInverse(RandomNumberGenerator &rng, const Integer &x) const =0
Calculates the inverse of an element.
Interface for private keys.
Definition: cryptlib.h:2186
Applies the inverse of the trapdoor function.
Definition: pubkey.h:183
virtual void LoadPrecomputation(BufferedTransformation &storedPrecomputation)
Retrieve previously saved precomputation.
Definition: cryptlib.h:2134
Rabin-Williams trapdoor function using the public key.
Definition: rw.h:23
virtual bool SupportsPrecomputation() const
Determines whether the object supports precomputation.
Definition: rw.h:110
void Initialize(RandomNumberGenerator &rng, unsigned int modulusBits)
Create a Rabin-Williams private key.
Definition: rw.h:82
Multiple precision integer with arithmetic operations.
Definition: integer.h:43
Applies the trapdoor function.
Definition: pubkey.h:128
void Load(BufferedTransformation &bt)
Loads a key from a BufferedTransformation.
Definition: rw.h:90
void Save(BufferedTransformation &bt) const
Saves a key to a BufferedTransformation.
Definition: rw.h:88
virtual bool Validate(RandomNumberGenerator &rng, unsigned int level) const =0
Check this object for errors.
void Initialize(const Integer &n)
Initialize a Rabin-Williams public key.
Definition: rw.h:31
Rabin-Williams signature scheme.
Definition: rw.h:139
virtual void GenerateRandom(RandomNumberGenerator &rng, const NameValuePairs &params=g_nullNameValuePairs)
Generate a random key or crypto parameters.
Definition: cryptlib.h:2166
void GenerateRandomWithKeySize(RandomNumberGenerator &rng, unsigned int keySize)
Generate a random key or crypto parameters.
Definition: cryptlib.cpp:780
Multiple precision integer with arithmetic operations.
Interface for public keys.
Definition: cryptlib.h:2181
Crypto++ library namespace.
virtual void Precompute(unsigned int unused=0)
Perform precomputation.
Definition: rw.h:111
Integer PreimageBound() const
Returns the maximum size of a message before the trapdoor function is applied.
Definition: rw.h:43
void Save(BufferedTransformation &bt) const
Saves a key to a BufferedTransformation.
Definition: rw.h:37
Rabin-Williams keys.
Definition: rw.h:128
InvertibleRWFunction()
Construct an InvertibleRWFunction.
Definition: rw.h:66
Interface for retrieving values given their names.
Definition: cryptlib.h:279
Trapdoor Function (TF) Signature Scheme.
Definition: pubkey.h:2070