Crypto++  5.6.3
Free C++ class library of cryptographic schemes
Go to the documentation of this file.
4 /** \file
5  This file contains classes that implement the
6  ESIGN signature schemes as defined in IEEE P1363a.
7 */
9 #include "cryptlib.h"
10 #include "pubkey.h"
11 #include "integer.h"
12 #include "asn.h"
13 #include "misc.h"
17 //! _
19 {
20  typedef ESIGNFunction ThisClass;
22 public:
23  void Initialize(const Integer &n, const Integer &e)
24  {m_n = n; m_e = e;}
26  // PublicKey
27  void BERDecode(BufferedTransformation &bt);
28  void DEREncode(BufferedTransformation &bt) const;
30  // CryptoMaterial
31  bool Validate(RandomNumberGenerator &rng, unsigned int level) const;
32  bool GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const;
33  void AssignFrom(const NameValuePairs &source);
35  // TrapdoorFunction
36  Integer ApplyFunction(const Integer &x) const;
37  Integer PreimageBound() const {return m_n;}
38  Integer ImageBound() const {return Integer::Power2(GetK());}
40  // non-derived
41  const Integer & GetModulus() const {return m_n;}
42  const Integer & GetPublicExponent() const {return m_e;}
44  void SetModulus(const Integer &n) {m_n = n;}
45  void SetPublicExponent(const Integer &e) {m_e = e;}
47 protected:
48  // Covertiy finding on overflow. The library allows small values for research purposes.
49  unsigned int GetK() const {return SaturatingSubtract(m_n.BitCount()/3, 1U);}
51  Integer m_n, m_e;
52 };
54 //! _
56 {
57  typedef InvertibleESIGNFunction ThisClass;
59 public:
60  void Initialize(const Integer &n, const Integer &e, const Integer &p, const Integer &q)
61  {m_n = n; m_e = e; m_p = p; m_q = q;}
62  // generate a random private key
63  void Initialize(RandomNumberGenerator &rng, unsigned int modulusBits)
64  {GenerateRandomWithKeySize(rng, modulusBits);}
67  void DEREncode(BufferedTransformation &bt) const;
71  // GeneratibleCryptoMaterial
72  bool Validate(RandomNumberGenerator &rng, unsigned int level) const;
73  bool GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const;
74  void AssignFrom(const NameValuePairs &source);
75  /*! parameters: (ModulusSize) */
78  const Integer& GetPrime1() const {return m_p;}
79  const Integer& GetPrime2() const {return m_q;}
81  void SetPrime1(const Integer &p) {m_p = p;}
82  void SetPrime2(const Integer &q) {m_q = q;}
84 protected:
85  Integer m_p, m_q;
86 };
88 //! _
89 template <class T>
91 {
92 public:
93  static const char *StaticAlgorithmName() {return "EMSA5";}
95  void ComputeMessageRepresentative(RandomNumberGenerator &rng,
96  const byte *recoverableMessage, size_t recoverableMessageLength,
97  HashTransformation &hash, HashIdentifier hashIdentifier, bool messageEmpty,
98  byte *representative, size_t representativeBitLength) const
99  {
100  CRYPTOPP_UNUSED(rng), CRYPTOPP_UNUSED(recoverableMessage), CRYPTOPP_UNUSED(recoverableMessageLength);
101  CRYPTOPP_UNUSED(messageEmpty), CRYPTOPP_UNUSED(hashIdentifier);
102  SecByteBlock digest(hash.DigestSize());
103  hash.Final(digest);
104  size_t representativeByteLength = BitsToBytes(representativeBitLength);
105  T mgf;
106  mgf.GenerateAndMask(hash, representative, representativeByteLength, digest, digest.size(), false);
107  if (representativeBitLength % 8 != 0)
108  representative[0] = (byte)Crop(representative[0], representativeBitLength % 8);
109  }
110 };
112 //! EMSA5, for use with ESIGN
114 {
116 };
119 {
120  static std::string StaticAlgorithmName() {return "ESIGN";}
121  typedef ESIGNFunction PublicKey;
123 };
125 //! ESIGN, as defined in IEEE P1363a
126 template <class H, class STANDARD = P1363_EMSA5>
127 struct ESIGN : public TF_SS<STANDARD, H, ESIGN_Keys>
128 {
129 };
133 #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:660
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:38
ESIGN, as defined in IEEE P1363a.
Definition: esign.h:127
Abstract base classes that provide a uniform interface to this library.
void DEREncode(BufferedTransformation &bt) const
Encode this object into a BufferedTransformation.
Definition: esign.cpp:141
Interface for random number generators.
Definition: cryptlib.h:1186
bool Validate(RandomNumberGenerator &rng, unsigned int level) const
Check this object for errors.
Definition: esign.cpp:192
SecBlock typedef.
Definition: secblock.h:730
Interface for buffered transformations.
Definition: cryptlib.h:1352
Interface for private keys.
Definition: cryptlib.h:2184
Base class for public key signature standard classes.
Definition: pubkey.h:2146
void BERDecode(BufferedTransformation &bt)
Decode this object from a BufferedTransformation.
Definition: esign.cpp:131
Definition: esign.h:90
Interface for message encoding method for public key signature schemes.
Definition: pubkey.h:408
T Crop(T value, size_t bits)
Truncates the value to the specified number of bits.
Definition: misc.h:648
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:37
static Integer Power2(size_t e)
Exponentiates to a power of 2.
Definition: integer.cpp:2927
Multiple precision integer with arithmetic operations.
Definition: integer.h:31
T1 SaturatingSubtract(const T1 &a, const T2 &b)
Performs a saturating subtract clamped at 0.
Definition: misc.h:865
Applies the trapdoor function.
Definition: pubkey.h:127
EMSA5, for use with ESIGN.
Definition: esign.h:113
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.
Interface for hash functions and data processing part of MACs.
Definition: cryptlib.h:922
void GenerateRandomWithKeySize(RandomNumberGenerator &rng, unsigned int keySize)
Generate a random key or crypto parameters.
Definition: cryptlib.cpp:771
Interface for public keys.
Definition: cryptlib.h:2179
Crypto++ library namespace.
Applies the inverse of the trapdoor function, using random data if required.
Definition: pubkey.h:159
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:954
Encode and decode ASN.1 objects with additional information.
Definition: asn.h:365
Interface for retrieving values given their names.
Definition: cryptlib.h:277
Trapdoor Function (TF) Signature Scheme.
Definition: pubkey.h:2180