DL_GroupParameters_DSA Class Reference

DSA group parameters. More...

Inheritance diagram for DL_GroupParameters_DSA:

## Public Types

enum | { MIN_PRIME_LENGTH = 1024 , MAX_PRIME_LENGTH = 3072 , PRIME_LENGTH_MULTIPLE = 1024 }
| DSA prime length. More...
Public Types inherited from DL_GroupParameters_IntegerBasedImpl< ModExpPrecomputation >
typedef GROUP_PRECOMP::Element | Element
Public Types inherited from DL_GroupParametersImpl< GROUP_PRECOMP, BASE_PRECOMP, BASE >
typedef GROUP_PRECOMP | GroupPrecomputation
typedef GROUP_PRECOMP::Element | Element
typedef BASE_PRECOMP | BasePrecomputation
Public Types inherited from DL_GroupParameters< typename GROUP_PRECOMP::Element >
typedef typename GROUP_PRECOMP::Element | Element

## Public Member Functions

bool | ValidateGroup (RandomNumberGenerator &rng, unsigned int level) const
| Check the group for errors. More...
void | GenerateRandom (RandomNumberGenerator &rng, const NameValuePairs &alg)
| Generate a random key or crypto parameters. More...
Public Member Functions inherited from DL_GroupParameters_GFP
bool | IsIdentity (const Integer &element) const
| Determines if an element is an identity. More...
void | SimultaneousExponentiate (Element *results, const Element &base, const Integer *exponents, unsigned int exponentsCount) const
| Exponentiates a base to multiple exponents. More...
bool | GetVoidValue (const char *name, const std::type_info &valueType, void *pValue) const
| Get a named value. More...
Element | MultiplyElements (const Element &a, const Element &b) const
Element | CascadeExponentiate (const Element &element1, const Integer &exponent1, const Element &element2, const Integer &exponent2) const
Public Member Functions inherited from DL_GroupParameters_IntegerBasedImpl< ModExpPrecomputation >
bool | GetVoidValue (const char *name, const std::type_info &valueType, void *pValue) const
| Get a named value. More...
void | AssignFrom (const NameValuePairs &source)
| Initialize or reinitialize this key. More...
const DL_FixedBasePrecomputation< Element > & | GetBasePrecomputation () const
| Retrieves the group precomputation. More...
DL_FixedBasePrecomputation< Element > & | AccessBasePrecomputation ()
| Retrieves the group precomputation. More...
const Integer & | GetModulus () const
| Retrieve the modulus for the group. More...
const Integer & | GetGenerator () const
| Retrieves a reference to the group generator. More...
void | SetModulusAndSubgroupGenerator (const Integer &p, const Integer &g)
| Set group parameters. More...
bool | operator== (const DL_GroupParameters_IntegerBasedImpl< ModExpPrecomputation, DL_FixedBasePrecomputationImpl< typename GROUP_PRECOMP::Element > > &rhs) const
bool | operator!= (const DL_GroupParameters_IntegerBasedImpl< ModExpPrecomputation, DL_FixedBasePrecomputationImpl< typename GROUP_PRECOMP::Element > > &rhs) const
Public Member Functions inherited from DL_GroupParametersImpl< GROUP_PRECOMP, BASE_PRECOMP, BASE >
const DL_GroupPrecomputation< Element > & | GetGroupPrecomputation () const
| Retrieves the group precomputation. More...
Public Member Functions inherited from DL_GroupParameters< typename GROUP_PRECOMP::Element >
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)
| Sets the subgroup generator. More...
virtual Element | ExponentiateBase (const Integer &exponent) const
| Exponentiates the base. More...
virtual Element | ExponentiateElement (const Element &base, const Integer &exponent) const
| Exponentiates an element. More...
virtual const Integer & | GetSubgroupOrder () 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 | 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...
Public Member Functions inherited from GeneratableCryptoMaterial
void | GenerateRandomWithKeySize (RandomNumberGenerator &rng, unsigned int keySize)
| Generate a random key or crypto parameters. More...
Public Member Functions inherited from CryptoMaterial
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 >
T | GetValueWithDefault (const char *name, T defaultValue) const
| Get a named value. More...
CRYPTOPP_DLL std::string | GetValueNames () const
| Get a list of value names that can be retrieved. More...
CRYPTOPP_DLL bool | GetIntValue (const char *name, int &value) const
| Get a named value with type int. More...
CRYPTOPP_DLL int | GetIntValueWithDefault (const char *name, int defaultValue) const
| Get a named value with type int, with default. More...
CRYPTOPP_DLL bool | GetWord64Value (const char *name, word64 &value) const
| Get a named value with type word64. More...
CRYPTOPP_DLL word64 | GetWord64ValueWithDefault (const char *name, word64 defaultValue) const
| Get a named value with type word64, with default. More...
template<class T >
void | GetRequiredParameter (const char *className, const char *name, T &value) const
| Retrieves a required name/value pair. More...
CRYPTOPP_DLL void | GetRequiredIntParameter (const char *className, const char *name, int &value) const
| Retrieves a required name/value pair. More...

## Static Public Member Functions

static bool | IsValidPrimeLength (unsigned int pbits)
| Check the prime length for errors. More...
Static Public Member Functions inherited from NameValuePairs
static CRYPTOPP_DLL 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

DSA group parameters.

These are GF(p) group parameters that are allowed by the DSA standard

See also
  DL_Keys_DSA

Since
  Crypto++ 1.0

Definition at line 732 of file gfpcrypt.h.

## Member Enumeration Documentation

## anonymous enum

anonymous enum

DSA prime length.

Enumerator
MIN_PRIME_LENGTH | Minimum prime length.
MAX_PRIME_LENGTH | Maximum prime length.
PRIME_LENGTH_MULTIPLE | Prime length multiple.

Definition at line 778 of file gfpcrypt.h.

## Member Function Documentation

## ValidateGroup()

bool DL_GroupParameters_DSA::ValidateGroup | ( | RandomNumberGenerator & | rng,
|  | unsigned int | level
| ) |  | const

virtual

Check the group for errors.

Parameters

  rng | RandomNumberGenerator for objects which use randomized testing
  level | level of thoroughness

Returns
  true if the tests succeed, false otherwise

ValidateGroup() also checks that the lengths of p and q are allowed by the DSA standard.

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.

Implements DL_GroupParameters< typename GROUP_PRECOMP::Element >.

## GenerateRandom()

void DL_GroupParameters_DSA::GenerateRandom | ( | RandomNumberGenerator & | rng,
|  | const NameValuePairs & | alg
| ) |  |

virtual

Generate a random key or crypto parameters.

Parameters

  rng | a RandomNumberGenerator to produce keying material
  alg | additional initialization parameters

NameValuePairs can be ModulusSize alone; or Modulus, SubgroupOrder, and SubgroupGenerator. ModulusSize must be between `DSA::MIN_PRIME_LENGTH` and `DSA::MAX_PRIME_LENGTH`, and divisible by `DSA::PRIME_LENGTH_MULTIPLE`.

An example of changing the modulus size using NameValuePairs is shown below.

     AlgorithmParameters params = MakeParameters
       (Name::ModulusSize(), 2048);

     DL_GroupParameters_DSA groupParams;
     groupParams.GenerateRandom(prng, params);

Exceptions

  KeyingErr | if a key can't be generated or algorithm parameters are invalid.

Reimplemented from GeneratableCryptoMaterial.

## IsValidPrimeLength()

static bool DL_GroupParameters_DSA::IsValidPrimeLength | ( | unsigned int | pbits | ) |

inline static

Check the prime length for errors.

Parameters

  pbits | number of bits in the prime number

Returns
  true if the tests succeed, false otherwise

Definition at line 774 of file gfpcrypt.h.

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

- gfpcrypt.h