Crypto++  5.6.5
Free C++ class library of cryptographic schemes
esign.h
Go to the documentation of this file.
1 // esign.h - written and placed in the public domain by Wei Dai
2 
3 //! \file esign.h
4 //! \brief Classes providing ESIGN signature schemes as defined in IEEE P1363a
5 //! \since Crypto++ 5.0
6 
7 #ifndef CRYPTOPP_ESIGN_H
8 #define CRYPTOPP_ESIGN_H
9 
10 #include "cryptlib.h"
11 #include "pubkey.h"
12 #include "integer.h"
13 #include "asn.h"
14 #include "misc.h"
15 
16 NAMESPACE_BEGIN(CryptoPP)
17 
18 //! \class ESIGNFunction
19 //! \brief ESIGN trapdoor function using the public key
20 //! \since Crypto++ 5.0
22 {
23  typedef ESIGNFunction ThisClass;
24 
25 public:
26 
27  //! \brief Initialize a ESIGN public key with {n,e}
28  //! \param n the modulus
29  //! \param e the public exponent
30  void Initialize(const Integer &n, const Integer &e)
31  {m_n = n; m_e = e;}
32 
33  // PublicKey
34  void BERDecode(BufferedTransformation &bt);
35  void DEREncode(BufferedTransformation &bt) const;
36 
37  // CryptoMaterial
38  bool Validate(RandomNumberGenerator &rng, unsigned int level) const;
39  bool GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const;
40  void AssignFrom(const NameValuePairs &source);
41 
42  // TrapdoorFunction
43  Integer ApplyFunction(const Integer &x) const;
44  Integer PreimageBound() const {return m_n;}
45  Integer ImageBound() const {return Integer::Power2(GetK());}
46 
47  // non-derived
48  const Integer & GetModulus() const {return m_n;}
49  const Integer & GetPublicExponent() const {return m_e;}
50 
51  void SetModulus(const Integer &n) {m_n = n;}
52  void SetPublicExponent(const Integer &e) {m_e = e;}
53 
54 protected:
55  // Covertiy finding on overflow. The library allows small values for research purposes.
56  unsigned int GetK() const {return SaturatingSubtract(m_n.BitCount()/3, 1U);}
57 
58  Integer m_n, m_e;
59 };
60 
61 //! \class InvertibleESIGNFunction
62 //! \brief ESIGN trapdoor function using the private key
63 //! \since Crypto++ 5.0
65 {
66  typedef InvertibleESIGNFunction ThisClass;
67 
68 public:
69 
70  //! \brief Initialize a ESIGN private key with {n,e,p,q}
71  //! \param n modulus
72  //! \param e public exponent
73  //! \param p first prime factor
74  //! \param q second prime factor
75  //! \details This Initialize() function overload initializes a private key from existing parameters.
76  void Initialize(const Integer &n, const Integer &e, const Integer &p, const Integer &q)
77  {m_n = n; m_e = e; m_p = p; m_q = q;}
78 
79  //! \brief Create a ESIGN private key
80  //! \param rng a RandomNumberGenerator derived class
81  //! \param modulusBits the size of the modulud, in bits
82  //! \details This function overload of Initialize() creates a new private key because it
83  //! takes a RandomNumberGenerator() as a parameter. If you have an existing keypair,
84  //! then use one of the other Initialize() overloads.
85  void Initialize(RandomNumberGenerator &rng, unsigned int modulusBits)
86  {GenerateRandomWithKeySize(rng, modulusBits);}
87 
89  void DEREncode(BufferedTransformation &bt) const;
90 
92 
93  // GeneratibleCryptoMaterial
94  bool Validate(RandomNumberGenerator &rng, unsigned int level) const;
95  bool GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const;
96  void AssignFrom(const NameValuePairs &source);
97  /*! parameters: (ModulusSize) */
99 
100  const Integer& GetPrime1() const {return m_p;}
101  const Integer& GetPrime2() const {return m_q;}
102 
103  void SetPrime1(const Integer &p) {m_p = p;}
104  void SetPrime2(const Integer &q) {m_q = q;}
105 
106 protected:
107  Integer m_p, m_q;
108 };
109 
110 //! \class EMSA5Pad
111 //! \brief EMSA5 padding method
112 //! \tparam T Mask Generation Function
113 //! \since Crypto++ 5.0
114 template <class T>
116 {
117 public:
118  CRYPTOPP_STATIC_CONSTEXPR const char* StaticAlgorithmName() {return "EMSA5";}
119 
120  void ComputeMessageRepresentative(RandomNumberGenerator &rng,
121  const byte *recoverableMessage, size_t recoverableMessageLength,
122  HashTransformation &hash, HashIdentifier hashIdentifier, bool messageEmpty,
123  byte *representative, size_t representativeBitLength) const
124  {
125  CRYPTOPP_UNUSED(rng), CRYPTOPP_UNUSED(recoverableMessage), CRYPTOPP_UNUSED(recoverableMessageLength);
126  CRYPTOPP_UNUSED(messageEmpty), CRYPTOPP_UNUSED(hashIdentifier);
127  SecByteBlock digest(hash.DigestSize());
128  hash.Final(digest);
129  size_t representativeByteLength = BitsToBytes(representativeBitLength);
130  T mgf;
131  mgf.GenerateAndMask(hash, representative, representativeByteLength, digest, digest.size(), false);
132  if (representativeBitLength % 8 != 0)
133  representative[0] = (byte)Crop(representative[0], representativeBitLength % 8);
134  }
135 };
136 
137 //! \class P1363_EMSA5
138 //! \brief EMSA5 padding method, for use with ESIGN
139 //! \since Crypto++ 5.0
141 {
143 };
144 
146 {
147  CRYPTOPP_STATIC_CONSTEXPR const char* StaticAlgorithmName() {return "ESIGN";}
148  typedef ESIGNFunction PublicKey;
150 };
151 
152 //! \class ESIGN
153 //! \brief ESIGN signature scheme, IEEE P1363a
154 //! \tparam H HashTransformation derived class
155 //! \tparam STANDARD Signature encoding method
156 //! \since Crypto++ 5.0
157 template <class H, class STANDARD = P1363_EMSA5>
158 struct ESIGN : public TF_SS<ESIGN_Keys, STANDARD, H>
159 {
160 };
161 
162 NAMESPACE_END
163 
164 #endif
Integer CalculateRandomizedInverse(RandomNumberGenerator &rng, const Integer &x) const
Applies the inverse of the trapdoor function, using random data if required.
Definition: esign.cpp:151
Utility functions for the Crypto++ library.
size_t BitsToBytes(size_t bitCount)
Returns the number of 8-bit bytes or octets required for the specified number of bits.
Definition: misc.h:749
This file contains helper classes/functions for implementing public key algorithms.
Integer ImageBound() const
Returns the maximum size of a message after the trapdoor function is applied.
Definition: esign.h:45
ESIGN signature scheme, IEEE P1363a.
Definition: esign.h:158
Abstract base classes that provide a uniform interface to this library.
void Initialize(const Integer &n, const Integer &e, const Integer &p, const Integer &q)
Initialize a ESIGN private key with {n,e,p,q}.
Definition: esign.h:76
void Initialize(const Integer &n, const Integer &e)
Initialize a ESIGN public key with {n,e}.
Definition: esign.h:30
void DEREncode(BufferedTransformation &bt) const
Encode this object into a BufferedTransformation.
Definition: esign.cpp:141
Interface for random number generators.
Definition: cryptlib.h:1188
bool Validate(RandomNumberGenerator &rng, unsigned int level) const
Check this object for errors.
Definition: esign.cpp:192
SecBlock typedef.
Definition: secblock.h:731
Interface for buffered transformations.
Definition: cryptlib.h:1352
Interface for private keys.
Definition: cryptlib.h:2186
Base class for public key signature standard classes.
Definition: pubkey.h:2036
void BERDecode(BufferedTransformation &bt)
Decode this object from a BufferedTransformation.
Definition: esign.cpp:131
EMSA5 padding method.
Definition: esign.h:115
Interface for message encoding method for public key signature schemes.
Definition: pubkey.h:398
T Crop(T value, size_t bits)
Truncates the value to the specified number of bits.
Definition: misc.h:737
void AssignFrom(const NameValuePairs &source)
Assign values to this object.
Definition: esign.cpp:213
Integer PreimageBound() const
Returns the maximum size of a message before the trapdoor function is applied.
Definition: esign.h:44
static Integer Power2(size_t e)
Exponentiates to a power of 2.
Definition: integer.cpp:3008
ESIGN trapdoor function using the private key.
Definition: esign.h:64
Multiple precision integer with arithmetic operations.
Definition: integer.h:43
T1 SaturatingSubtract(const T1 &a, const T2 &b)
Performs a saturating subtract clamped at 0.
Definition: misc.h:847
Applies the trapdoor function.
Definition: pubkey.h:128
EMSA5 padding method, for use with ESIGN.
Definition: esign.h:140
Classes and functions for working with ANS.1 objects.
bool GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const
Get a named value.
Definition: esign.cpp:205
virtual unsigned int DigestSize() const =0
Provides the digest size of the hash.
ESIGN trapdoor function using the public key.
Definition: esign.h:21
Interface for hash functions and data processing part of MACs.
Definition: cryptlib.h:930
void GenerateRandomWithKeySize(RandomNumberGenerator &rng, unsigned int keySize)
Generate a random key or crypto parameters.
Definition: cryptlib.cpp:780
Multiple precision integer with arithmetic operations.
void Initialize(RandomNumberGenerator &rng, unsigned int modulusBits)
Create a ESIGN private key.
Definition: esign.h:85
Interface for public keys.
Definition: cryptlib.h:2181
Crypto++ library namespace.
Applies the inverse of the trapdoor function, using random data if required.
Definition: pubkey.h:158
void GenerateRandom(RandomNumberGenerator &rng, const NameValuePairs &alg)
Definition: esign.cpp:86
virtual void Final(byte *digest)
Computes the hash of the current message.
Definition: cryptlib.h:960
Encode and decode ASN.1 objects with additional information.
Definition: asn.h:373
Interface for retrieving values given their names.
Definition: cryptlib.h:279
Trapdoor Function (TF) Signature Scheme.
Definition: pubkey.h:2070