Crypto++ 8.1 Free C++ class library of cryptographic schemes

Public Types | Public Member Functions | Static Public Member Functions | List of all members
DL_GroupParameters_EC< EC > Class Template Reference

Elliptic Curve Parameters. More...

Inheritance diagram for DL_GroupParameters_EC< EC >:

## Public Types
typedef EC | EllipticCurve
typedef EllipticCurve::Point | Point
typedef Point | Element
typedef IncompatibleCofactorMultiplication | DefaultCofactorOption
Public Types inherited from DL_GroupParametersImpl< EcPrecomputation< EC > >
typedef EcPrecomputation< EC > | GroupPrecomputation
typedef EcPrecomputation< EC > ::Element | Element
typedef DL_FixedBasePrecomputationImpl< typename EcPrecomputation< EC > ::Element > | BasePrecomputation
Public Types inherited from DL_GroupParameters< typename EcPrecomputation< EC > ::Element >
typedef typename EcPrecomputation< EC > ::Element | Element

## Public Member Functions
| DL_GroupParameters_EC ()
| Construct an EC GroupParameters.
| DL_GroupParameters_EC (const OID &oid)
| Construct an EC GroupParameters. More...
| DL_GroupParameters_EC (const EllipticCurve &ec, const Point &G, const Integer &n, const Integer &k=Integer::Zero())
| Construct an EC GroupParameters. More...
| DL_GroupParameters_EC (BufferedTransformation &bt)
| Construct an EC GroupParameters. More...
void | Initialize (const EllipticCurve &ec, const Point &G, const Integer &n, const Integer &k=Integer::Zero())
| Initialize an EC GroupParameters using {EC,G,n,k}. More...
void | Initialize (const OID &oid)
| Initialize a DL_GroupParameters_EC {EC,G,n,k}. More...
bool | GetVoidValue (const char *name, const std::type_info &valueType, void *pValue) const
| Get a named value. More...
void | AssignFrom (const NameValuePairs &source)
| Assign values to this object. More...
void | GenerateRandom (RandomNumberGenerator &rng, const NameValuePairs &alg)
| this implementation doesn't actually generate a curve, it just initializes the parameters with existing values More...
const DL_FixedBasePrecomputation< Element > & | GetBasePrecomputation () const
| Retrieves the group precomputation. More...
DL_FixedBasePrecomputation< Element > & | AccessBasePrecomputation ()
| Retrieves the group precomputation. More...
const Integer & | GetSubgroupOrder () const
| Retrieves the subgroup order. More...
Integer | GetCofactor () const
| Retrieves the cofactor. More...
bool | ValidateGroup (RandomNumberGenerator &rng, unsigned int level) const
| Check the group for errors. More...
bool | ValidateElement (unsigned int level, const Element &element, const DL_FixedBasePrecomputation< Element > *precomp) const
bool | FastSubgroupCheckAvailable () const
void | EncodeElement (bool reversible, const Element &element, byte *encoded) const
virtual unsigned int | GetEncodedElementSize (bool reversible) const
| Retrieves the encoded element's size. More...
Element | DecodeElement (const byte *encoded, bool checkForGroupMembership) const
| Decodes the element. More...
Integer | ConvertElementToInteger (const Element &element) const
Integer | GetMaxExponent () const
| Retrieves the maximum exponent for the group. More...
bool | IsIdentity (const Element &element) const
void | SimultaneousExponentiate (Element *results, const Element &base, const Integer *exponents, unsigned int exponentsCount) const
OID | GetAlgorithmID () const
Element | MultiplyElements (const Element &a, const Element &b) const
Element | CascadeExponentiate (const Element &element1, const Integer &exponent1, const Element &element2, const Integer &exponent2) const
void | BERDecode (BufferedTransformation &bt)
void | DEREncode (BufferedTransformation &bt) const
void | SetPointCompression (bool compress)
bool | GetPointCompression () const
void | SetEncodeAsOID (bool encodeAsOID)
bool | GetEncodeAsOID () const
const EllipticCurve & | GetCurve () const
bool | operator== (const ThisClass &rhs) const
Public Member Functions inherited from DL_GroupParametersImpl< EcPrecomputation< EC > >
const DL_GroupPrecomputation< Element > & | GetGroupPrecomputation () const
| Retrieves the group precomputation. More...
const DL_FixedBasePrecomputation< Element > & | GetBasePrecomputation () const
| Retrieves the group precomputation. More...
DL_FixedBasePrecomputation< Element > & | AccessBasePrecomputation ()
| Retrieves the group precomputation. More...
Public Member Functions inherited from DL_GroupParameters< typename EcPrecomputation< EC > ::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 Integer | GetGroupOrder () const
| Retrieves the order of the group. More...
virtual void | EncodeElement (bool reversible, const Element &element, byte *encoded) const=0
| Encodes 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 | 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
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...
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...
bool | GetWord64Value (const char *name, word64 &value) const
| Get a named value with type word64. More...
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...
void | GetRequiredIntParameter (const char *className, const char *name, int &value) const
| Retrieves a required name/value pair. More...

## Static Public Member Functions
static std::string | StaticAlgorithmNamePrefix ()
static OID | GetNextRecommendedParametersOID (const OID &oid)
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 EC>
class DL_GroupParameters_EC< EC >

Elliptic Curve Parameters.

Template Parameters

  EC | elliptic curve field

This class corresponds to the ASN.1 sequence of the same name in ANSI X9.62 and SEC 1. EC is currently defined for ECP and EC2N.

Definition at line 37 of file eccrypto.h.

## Constructor & Destructor Documentation

## ◆ DL_GroupParameters_EC() [1/3]

template<class EC>

DL_GroupParameters_EC< EC >::DL_GroupParameters_EC | ( | const OID & | oid | ) |
| inline

Construct an EC GroupParameters.

Parameters

  oid | the OID of a curve

Definition at line 54 of file eccrypto.h.

## ◆ DL_GroupParameters_EC() [2/3]

template<class EC>

DL_GroupParameters_EC< EC >::DL_GroupParameters_EC | ( | const EllipticCurve & | ec,
|  | const Point & | G,
|  | const Integer & | n,
|  | const Integer & | k = `Integer::Zero()`
| ) |  |
| inline

Construct an EC GroupParameters.

Parameters

  ec | the elliptic curve
  G | the base point
  n | the order of the base point
  k | the cofactor

Definition at line 62 of file eccrypto.h.

## ◆ DL_GroupParameters_EC() [3/3]

template<class EC>

DL_GroupParameters_EC< EC >::DL_GroupParameters_EC | ( | BufferedTransformation & | bt | ) |
| inline

Construct an EC GroupParameters.

Parameters

  bt | BufferedTransformation with group parameters

Definition at line 67 of file eccrypto.h.

## Member Function Documentation

## ◆ Initialize() [1/2]

template<class EC>

void DL_GroupParameters_EC< EC >::Initialize | ( | const EllipticCurve & | ec,
|  | const Point & | G,
|  | const Integer & | n,
|  | const Integer & | k = `Integer::Zero()`
| ) |  |
| inline

Initialize an EC GroupParameters using {EC,G,n,k}.

Parameters

  ec | the elliptic curve
  G | the base point
  n | the order of the base point
  k | the cofactor

This Initialize() function overload initializes group parameters from existing parameters.

Definition at line 76 of file eccrypto.h.

## ◆ Initialize() [2/2]

template<class EC >

void DL_GroupParameters_EC< EC >::Initialize | ( | const OID & | oid | ) |

Initialize a DL_GroupParameters_EC {EC,G,n,k}.

Parameters

  oid | the OID of a curve

This Initialize() function overload initializes group parameters from existing parameters.

Definition at line 467 of file eccrypto.cpp.

## ◆ GetVoidValue()

template<class EC >

bool DL_GroupParameters_EC< EC >::GetVoidValue | ( | const char * | name,
|  | const std::type_info & | valueType,
|  | void * | pValue
| ) |  | const
| virtual

Get a named value.

Parameters

  name | the name of the object or value to retrieve
  valueType | reference to a variable that receives the value
  pValue | void pointer to a variable that receives the value

Returns
  true if the value was retrieved, false otherwise

GetVoidValue() retrieves 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 494 of file eccrypto.cpp.

## ◆ AssignFrom()

template<class EC >

void DL_GroupParameters_EC< EC >::AssignFrom | ( | const NameValuePairs & | source | ) |
| virtual

Assign values to this object.

This function can be used to create a public key from a private key.

Implements CryptoMaterial.

Definition at line 511 of file eccrypto.cpp.

## ◆ GenerateRandom()

template<class EC >

void DL_GroupParameters_EC< EC >::GenerateRandom | ( | RandomNumberGenerator & | rng,
|  | const NameValuePairs & | alg
| ) |  |
| virtual

this implementation doesn't actually generate a curve, it just initializes the parameters with existing values

parameters: (Curve, SubgroupGenerator, SubgroupOrder, Cofactor (optional)), or (GroupOID)

Reimplemented from GeneratableCryptoMaterial.

Definition at line 532 of file eccrypto.cpp.

## ◆ GetBasePrecomputation()

template<class EC>

const DL_FixedBasePrecomputation<Element>& DL_GroupParameters_EC< EC >::GetBasePrecomputation | ( |  | ) | const
| inline virtual

Retrieves the group precomputation.

Returns
  a const reference to the group precomputation using a fixed base

Implements DL_GroupParameters< typename EcPrecomputation< EC > ::Element >.

Definition at line 99 of file eccrypto.h.

## ◆ AccessBasePrecomputation()

template<class EC>

DL_FixedBasePrecomputation<Element>& DL_GroupParameters_EC< EC >::AccessBasePrecomputation | ( |  | ) |
| inline virtual

Retrieves the group precomputation.

Returns
  a non-const reference to the group precomputation using a fixed base

Implements DL_GroupParameters< typename EcPrecomputation< EC > ::Element >.

Definition at line 100 of file eccrypto.h.

## ◆ GetSubgroupOrder()

template<class EC>

const Integer& DL_GroupParameters_EC< EC >::GetSubgroupOrder | ( |  | ) | const
| inline virtual

Retrieves the subgroup order.

Returns
  the order of subgroup generated by the base element

Implements DL_GroupParameters< typename EcPrecomputation< EC > ::Element >.

Definition at line 101 of file eccrypto.h.

## ◆ GetCofactor()

template<class EC >

Integer DL_GroupParameters_EC< EC >::GetCofactor | ( |  | ) | const
| virtual

Retrieves the cofactor.

Returns
  the cofactor

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

Reimplemented from DL_GroupParameters< typename EcPrecomputation< EC > ::Element >.

Definition at line 592 of file eccrypto.cpp.

## ◆ ValidateGroup()

template<class EC >

bool DL_GroupParameters_EC< EC >::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

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.

Implements DL_GroupParameters< typename EcPrecomputation< EC > ::Element >.

Definition at line 611 of file eccrypto.cpp.

## ◆ GetEncodedElementSize()

template<class EC>

virtual unsigned int DL_GroupParameters_EC< EC >::GetEncodedElementSize | ( | bool | reversible | ) | const
| inline virtual

Retrieves the encoded element's size.

Parameters

  reversible | flag 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()

Implements DL_GroupParameters< typename EcPrecomputation< EC > ::Element >.

Definition at line 113 of file eccrypto.h.

## ◆ DecodeElement()

template<class EC>

Element DL_GroupParameters_EC< EC >::DecodeElement | ( | const byte * | encoded,
|  | bool | checkForGroupMembership
| ) |  | const
| inline virtual

Decodes the element.

Parameters

  encoded | byte array with the encoded element
  checkForGroupMembership | flag indicating if the element should be validated

Returns
  Element after decoding

DecodeElement() must be implemented in a derived class.

Precondition
  `COUNTOF(encoded) == GetEncodedElementSize()`

Implements DL_GroupParameters< typename EcPrecomputation< EC > ::Element >.

Definition at line 120 of file eccrypto.h.

## ◆ GetMaxExponent()

template<class EC>

Integer DL_GroupParameters_EC< EC >::GetMaxExponent | ( |  | ) | const
| inline virtual

Retrieves the maximum exponent for the group.

Returns
  the maximum exponent for the group

Implements DL_GroupParameters< typename EcPrecomputation< EC > ::Element >.

Definition at line 130 of file eccrypto.h.

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

- eccrypto.h
- eccrypto.cpp