Crypto++  5.6.3
Free C++ class library of cryptographic schemes
Public Types | Public Member Functions | List of all members
DL_GroupParameters< T > Class Template Referenceabstract

Interface for Discrete Log (DL) group parameters. More...

+ Inheritance diagram for DL_GroupParameters< T >:

Public Types

typedef T Element
 

Public Member Functions

bool Validate (RandomNumberGenerator &rng, unsigned int level) const
 Check this object for errors. More...
 
bool GetVoidValue (const char *name, const std::type_info &valueType, void *pValue) const
 Get a named value. More...
 
bool SupportsPrecomputation () const
 Determines whether the object supports precomputation. More...
 
void Precompute (unsigned int precomputationStorage=16)
 Perform precomputation. More...
 
void LoadPrecomputation (BufferedTransformation &storedPrecomputation)
 Retrieve previously saved precomputation. More...
 
void SavePrecomputation (BufferedTransformation &storedPrecomputation) const
 Save precomputation for later use. More...
 
virtual const Element & GetSubgroupGenerator () const
 Retrieves the subgroup generator. More...
 
virtual void SetSubgroupGenerator (const Element &base)
 Set the subgroup generator. More...
 
virtual Element ExponentiateBase (const Integer &exponent) const
 Retrieves the subgroup generator. More...
 
virtual Element ExponentiateElement (const Element &base, const Integer &exponent) const
 Exponentiates an element. More...
 
virtual const DL_GroupPrecomputation< Element > & GetGroupPrecomputation () const =0
 Retrieves the group precomputation. More...
 
virtual const DL_FixedBasePrecomputation< Element > & GetBasePrecomputation () const =0
 Retrieves the group precomputation. More...
 
virtual DL_FixedBasePrecomputation< Element > & AccessBasePrecomputation ()=0
 Retrieves the group precomputation. More...
 
virtual const IntegerGetSubgroupOrder () const =0
 Retrieves the subgroup order. More...
 
virtual Integer GetMaxExponent () const =0
 Retrieves the maximum exponent for the group. More...
 
virtual Integer GetGroupOrder () const
 Retrieves the order of the group. More...
 
virtual Integer GetCofactor () const
 Retrieves the cofactor. More...
 
virtual unsigned int GetEncodedElementSize (bool reversible) const =0
 Retrieves the encoded element's size. More...
 
virtual void EncodeElement (bool reversible, const Element &element, byte *encoded) const =0
 Encodes the element. More...
 
virtual Element DecodeElement (const byte *encoded, bool checkForGroupMembership) const =0
 Decodes the element. More...
 
virtual Integer ConvertElementToInteger (const Element &element) const =0
 Converts an element to an Integer. More...
 
virtual bool ValidateGroup (RandomNumberGenerator &rng, unsigned int level) const =0
 Check the group for errors. More...
 
virtual bool ValidateElement (unsigned int level, const Element &element, const DL_FixedBasePrecomputation< Element > *precomp) const =0
 Check the element for errors. More...
 
virtual bool FastSubgroupCheckAvailable () const =0
 
virtual bool IsIdentity (const Element &element) const =0
 Determines if an element is an identity. More...
 
virtual void SimultaneousExponentiate (Element *results, const Element &base, const Integer *exponents, unsigned int exponentsCount) const =0
 Exponentiates a base to multiple exponents. More...
 
- Public Member Functions inherited from GeneratableCryptoMaterial
virtual void GenerateRandom (RandomNumberGenerator &rng, const NameValuePairs &params=g_nullNameValuePairs)
 Generate a random key or crypto parameters. More...
 
void GenerateRandomWithKeySize (RandomNumberGenerator &rng, unsigned int keySize)
 Generate a random key or crypto parameters. More...
 
- Public Member Functions inherited from CryptoMaterial
virtual void AssignFrom (const NameValuePairs &source)=0
 Assign values to this object. More...
 
virtual void ThrowIfInvalid (RandomNumberGenerator &rng, unsigned int level) const
 Check this object for errors. More...
 
virtual void Save (BufferedTransformation &bt) const
 Saves a key to a BufferedTransformation. More...
 
virtual void Load (BufferedTransformation &bt)
 Loads a key from a BufferedTransformation. More...
 
void DoQuickSanityCheck () const
 Perform a quick sanity check. More...
 
- Public Member Functions inherited from NameValuePairs
template<class T >
bool GetThisObject (T &object) const
 Get a copy of this object or subobject. More...
 
template<class T >
bool GetThisPointer (T *&ptr) const
 Get a pointer to this object. More...
 
template<class T >
bool GetValue (const char *name, T &value) const
 Get a named value. More...
 
template<class T >
GetValueWithDefault (const char *name, T defaultValue) const
 Get a named value. More...
 
std::string GetValueNames () const
 Get a list of value names that can be retrieved. More...
 
bool GetIntValue (const char *name, int &value) const
 Get a named value with type int. More...
 
int GetIntValueWithDefault (const char *name, int defaultValue) const
 Get a named value with type int, with default. More...
 
template<class T >
void GetRequiredParameter (const char *className, const char *name, T &value) const
 Retrieves a required name/value pair. More...
 
void GetRequiredIntParameter (const char *className, const char *name, int &value) const
 Retrieves a required name/value pair. More...
 

Additional Inherited Members

- Static Public Member Functions inherited from NameValuePairs
static void ThrowIfTypeMismatch (const char *name, const std::type_info &stored, const std::type_info &retrieving)
 Ensures an expected name and type is present. More...
 

Detailed Description

template<class T>
class DL_GroupParameters< T >

Interface for Discrete Log (DL) group parameters.

Template Parameters
Telement in the group

The element is usually an Integer, ECP::Point or EC2N::Point

Definition at line 748 of file pubkey.h.

Member Function Documentation

template<class T>
bool DL_GroupParameters< T >::Validate ( RandomNumberGenerator rng,
unsigned int  level 
) const
inlinevirtual

Check this object for errors.

Parameters
rnga RandomNumberGenerator for objects which use randomized testing
levelthe level of thoroughness
Returns
true if the tests succeed, false otherwise

There are four levels of thoroughness:

  • 0 - using this object won't cause a crash or exception
  • 1 - this object will probably function, and encrypt, sign, other operations correctly
  • 2 - ensure this object will function correctly, and perform reasonable security checks
  • 3 - perform reasonable security checks, and do checks that may take a long time

Level 0 does not require a RandomNumberGenerator. A NullRNG() can be used for level 0. Level 1 may not check for weak keys and such. Levels 2 and 3 are recommended.

See also
ThrowIfInvalid()

Implements CryptoMaterial.

Definition at line 758 of file pubkey.h.

template<class T>
bool DL_GroupParameters< T >::GetVoidValue ( const char *  name,
const std::type_info &  valueType,
void *  pValue 
) const
inlinevirtual

Get a named value.

Parameters
namethe name of the object or value to retrieve
valueTypereference to a variable that receives the value
pValuevoid pointer to a variable that receives the value
Returns
true if the value was retrieved, false otherwise

GetVoidValue() retrives the value of name if it exists.

Note
GetVoidValue() is an internal function and should be implemented by derived classes. Users should use one of the other functions instead.
See also
GetValue(), GetValueWithDefault(), GetIntValue(), GetIntValueWithDefault(), GetRequiredParameter() and GetRequiredIntParameter()

Implements NameValuePairs.

Definition at line 774 of file pubkey.h.

template<class T>
bool DL_GroupParameters< T >::SupportsPrecomputation ( ) const
inlinevirtual

Determines whether the object supports precomputation.

Returns
true if the object supports precomputation, false otherwise
See also
Precompute()

Reimplemented from CryptoMaterial.

Definition at line 782 of file pubkey.h.

template<class T>
void DL_GroupParameters< T >::Precompute ( unsigned int  precomputationStorage = 16)
inlinevirtual

Perform precomputation.

Parameters
precomputationStoragethe suggested number of objects for the precompute table
Exceptions
NotImplemented

The exact semantics of Precompute() varies, but it typically means calculate a table of n objects that can be used later to speed up computation.

If a derived class does not override Precompute(), then the base class throws NotImplemented.

See also
SupportsPrecomputation(), LoadPrecomputation(), SavePrecomputation()

Reimplemented from CryptoMaterial.

Definition at line 784 of file pubkey.h.

template<class T>
void DL_GroupParameters< T >::LoadPrecomputation ( BufferedTransformation storedPrecomputation)
inlinevirtual

Retrieve previously saved precomputation.

Parameters
storedPrecomputationBufferedTransformation with the saved precomputation
Exceptions
NotImplemented
See also
SupportsPrecomputation(), Precompute()

Reimplemented from CryptoMaterial.

Definition at line 789 of file pubkey.h.

template<class T>
void DL_GroupParameters< T >::SavePrecomputation ( BufferedTransformation storedPrecomputation) const
inlinevirtual

Save precomputation for later use.

Parameters
storedPrecomputationBufferedTransformation to write the precomputation
Exceptions
NotImplemented
See also
SupportsPrecomputation(), Precompute()

Reimplemented from CryptoMaterial.

Definition at line 795 of file pubkey.h.

template<class T>
virtual const Element& DL_GroupParameters< T >::GetSubgroupGenerator ( ) const
inlinevirtual

Retrieves the subgroup generator.

Returns
the subgroup generator

The subgroup generator is retrieved from the base precomputation

Definition at line 803 of file pubkey.h.

template<class T>
virtual void DL_GroupParameters< T >::SetSubgroupGenerator ( const Element &  base)
inlinevirtual

Set the subgroup generator.

Parameters
basethe new subgroup generator

The subgroup generator is set in the base precomputation

Definition at line 808 of file pubkey.h.

template<class T>
virtual Element DL_GroupParameters< T >::ExponentiateBase ( const Integer exponent) const
inlinevirtual

Retrieves the subgroup generator.

Returns
the subgroup generator

The subgroup generator is retrieved from the base precomputation.

Definition at line 813 of file pubkey.h.

template<class T>
virtual Element DL_GroupParameters< T >::ExponentiateElement ( const Element &  base,
const Integer exponent 
) const
inlinevirtual

Exponentiates an element.

Parameters
basethe base elemenet
exponentthe exponent to raise the base
Returns
the result of the exponentiation

Internally, ExponentiateElement() calls SimultaneousExponentiate().

Definition at line 823 of file pubkey.h.

template<class T>
virtual const DL_GroupPrecomputation<Element>& DL_GroupParameters< T >::GetGroupPrecomputation ( ) const
pure virtual
template<class T>
virtual const DL_FixedBasePrecomputation<Element>& DL_GroupParameters< T >::GetBasePrecomputation ( ) const
pure virtual
template<class T>
virtual DL_FixedBasePrecomputation<Element>& DL_GroupParameters< T >::AccessBasePrecomputation ( )
pure virtual
template<class T>
virtual const Integer& DL_GroupParameters< T >::GetSubgroupOrder ( ) const
pure virtual

Retrieves the subgroup order.

Returns
the order of subgroup generated by the base element

Implemented in DL_GroupParameters_EC< EC >, and DL_GroupParameters_IntegerBased.

template<class T>
virtual Integer DL_GroupParameters< T >::GetMaxExponent ( ) const
pure virtual

Retrieves the maximum exponent for the group.

Returns
the maximum exponent for the group

Implemented in DL_GroupParameters_EC< EC >, and DL_GroupParameters_IntegerBased.

template<class T>
virtual Integer DL_GroupParameters< T >::GetGroupOrder ( ) const
inlinevirtual

Retrieves the order of the group.

Returns
the order of the group

Either GetGroupOrder() or GetCofactor() must be overriden in a derived class.

Reimplemented in DL_GroupParameters_IntegerBased.

Definition at line 853 of file pubkey.h.

template<class T>
virtual Integer DL_GroupParameters< T >::GetCofactor ( ) const
inlinevirtual

Retrieves the cofactor.

Returns
the cofactor

Either GetGroupOrder() or GetCofactor() must be overriden in a derived class.

Reimplemented in DL_GroupParameters_EC< EC >.

Definition at line 858 of file pubkey.h.

template<class T>
virtual unsigned int DL_GroupParameters< T >::GetEncodedElementSize ( bool  reversible) const
pure virtual

Retrieves the encoded element's size.

Parameters
reversibleflag indicating the encoding format
Returns
encoded element's size, in bytes

The format of the encoded element varies by the underlyinhg type of the element and the reversible flag. GetEncodedElementSize() must be implemented in a derived class.

See also
GetEncodedElementSize(), EncodeElement(), DecodeElement()

Implemented in DL_GroupParameters_EC< EC >, and DL_GroupParameters_IntegerBased.

template<class T>
virtual void DL_GroupParameters< T >::EncodeElement ( bool  reversible,
const Element &  element,
byte *  encoded 
) const
pure virtual

Encodes the element.

Parameters
reversibleflag indicating the encoding format
elementreference to the element to encode
encodeddestination byte array for the encoded element

EncodeElement() must be implemented in a derived class.

Precondition
COUNTOF(encoded) == GetEncodedElementSize()

Implemented in DL_GroupParameters_IntegerBased.

template<class T>
virtual Element DL_GroupParameters< T >::DecodeElement ( const byte *  encoded,
bool  checkForGroupMembership 
) const
pure virtual

Decodes the element.

Parameters
encodedbyte array with the encoded element
checkForGroupMembershipflag indicating if the element should be validated
Returns
Element after decoding

DecodeElement() must be implemented in a derived class.

Precondition
COUNTOF(encoded) == GetEncodedElementSize()

Implemented in DL_GroupParameters_EC< EC >, and DL_GroupParameters_IntegerBased.

template<class T>
virtual Integer DL_GroupParameters< T >::ConvertElementToInteger ( const Element &  element) const
pure virtual

Converts an element to an Integer.

Parameters
elementthe element to convert to an Integer
Returns
Element after converting to an Integer

ConvertElementToInteger() must be implemented in a derived class.

Implemented in DL_GroupParameters_IntegerBased.

template<class T>
virtual bool DL_GroupParameters< T >::ValidateGroup ( RandomNumberGenerator rng,
unsigned int  level 
) const
pure virtual

Check the group for errors.

Parameters
rngRandomNumberGenerator for objects which use randomized testing
levellevel of thoroughness
Returns
true if the tests succeed, false otherwise

There are four levels of thoroughness:

  • 0 - using this object won't cause a crash or exception
  • 1 - this object will probably function, and encrypt, sign, other operations correctly
  • 2 - ensure this object will function correctly, and perform reasonable security checks
  • 3 - perform reasonable security checks, and do checks that may take a long time

Level 0 does not require a RandomNumberGenerator. A NullRNG() can be used for level 0. Level 1 may not check for weak keys and such. Levels 2 and 3 are recommended.

ValidateGroup() must be implemented in a derived class.

Implemented in DL_GroupParameters_DSA, DL_GroupParameters_EC< EC >, and DL_GroupParameters_IntegerBased.

template<class T>
virtual bool DL_GroupParameters< T >::ValidateElement ( unsigned int  level,
const Element &  element,
const DL_FixedBasePrecomputation< Element > *  precomp 
) const
pure virtual

Check the element for errors.

Parameters
levellevel of thoroughness
elementelement to check
precompoptional pointer to DL_FixedBasePrecomputation
Returns
true if the tests succeed, false otherwise

There are four levels of thoroughness:

  • 0 - using this object won't cause a crash or exception
  • 1 - this object will probably function, and encrypt, sign, other operations correctly
  • 2 - ensure this object will function correctly, and perform reasonable security checks
  • 3 - perform reasonable security checks, and do checks that may take a long time

Level 0 performs group membership checks. Level 1 may not check for weak keys and such. Levels 2 and 3 are recommended.

ValidateElement() must be implemented in a derived class.

Implemented in DL_GroupParameters_IntegerBased.

template<class T>
virtual bool DL_GroupParameters< T >::IsIdentity ( const Element &  element) const
pure virtual

Determines if an element is an identity.

Parameters
elementelement to check
Returns
true if the element is an identity, false otherwise

The identity element or or neutral element is a special element in a group that leaves other elements unchanged when combined with it.

IsIdentity() must be implemented in a derived class.

Implemented in DL_GroupParameters_LUC, and DL_GroupParameters_GFP.

template<class T>
virtual void DL_GroupParameters< T >::SimultaneousExponentiate ( Element *  results,
const Element &  base,
const Integer exponents,
unsigned int  exponentsCount 
) const
pure virtual

Exponentiates a base to multiple exponents.

Parameters
resultsan array of Elements
basethe base to raise to the exponents
exponentsan array of exponents
exponentsCountthe number of exponents in the array

SimultaneousExponentiate() raises the base to each exponent in the exponents array and stores the result at the respective position in the results array.

SimultaneousExponentiate() must be implemented in a derived class.

Precondition
COUNTOF(results) == exponentsCount
COUNTOF(exponents) == exponentsCount

Implemented in DL_GroupParameters_LUC.


The documentation for this class was generated from the following file: