Rabin-Williams trapdoor function using the public key. More...

#include <rw.h>

Inheritance diagram for RWFunction:

Collaboration diagram for RWFunction:

Public Member Functions
void	Initialize (const Integer &n)
	Initialize a Rabin-Williams public key. More...

void	BERDecode (BufferedTransformation &bt)

void	DEREncode (BufferedTransformation &bt) const

void	Save (BufferedTransformation &bt) const
	Saves a key to a BufferedTransformation. More...

void	Load (BufferedTransformation &bt)
	Loads a key from a BufferedTransformation. More...

Integer	ApplyFunction (const Integer &x) const
	Applies the trapdoor. More...

Integer	PreimageBound () const
	Returns the maximum size of a message before the trapdoor function is applied. More...

Integer	ImageBound () const
	Returns the maximum size of a message after the trapdoor function is applied. More...

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...

void	AssignFrom (const NameValuePairs &source)
	Assign values to this object. More...

const Integer &	GetModulus () const

void	SetModulus (const Integer &n)

Public Member Functions inherited from TrapdoorFunction
virtual	~TrapdoorFunction ()

Integer	ApplyRandomizedFunction (RandomNumberGenerator &rng, const Integer &x) const
	Applies the trapdoor function. More...

bool	IsRandomized () const
	Determines if the encryption algorithm is randomized. More...

Public Member Functions inherited from RandomizedTrapdoorFunction
virtual	~RandomizedTrapdoorFunction ()

Public Member Functions inherited from TrapdoorFunctionBounds
virtual	~TrapdoorFunctionBounds ()

virtual Integer	MaxPreimage () const
	Returns the maximum size of a message before the trapdoor function is applied bound to a public key. More...

virtual Integer	MaxImage () const
	Returns the maximum size of a message after the trapdoor function is applied bound to a public key. More...

Public Member Functions inherited from CryptoMaterial
virtual	~CryptoMaterial ()

virtual void	ThrowIfInvalid (RandomNumberGenerator &rng, unsigned int level) const
	Check this object for errors. More...

virtual bool	SupportsPrecomputation () const
	Determines whether the object supports precomputation. More...

virtual void	Precompute (unsigned int precomputationStorage)
	Perform precomputation. More...

virtual void	LoadPrecomputation (BufferedTransformation &storedPrecomputation)
	Retrieve previously saved precomputation. More...

virtual void	SavePrecomputation (BufferedTransformation &storedPrecomputation) const
	Save precomputation for later use. More...

void	DoQuickSanityCheck () const
	Perform a quick sanity check. More...

Public Member Functions inherited from NameValuePairs
virtual	~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...

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...

Protected Attributes
Integer	m_n

Private Types
typedef RWFunction	ThisClass

Additional Inherited Members
Static Public Member Functions inherited from NameValuePairs
static CRYPTOPP_DLL void CRYPTOPP_API	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

Rabin-Williams trapdoor function using the public key.

Since: Crypto++ 2.0, Tweaked roots using e and f since Crypto++ 5.6.4

Definition at line 23 of file rw.h.

Member Typedef Documentation

typedef RWFunction RWFunction::ThisClass

private

Definition at line 25 of file rw.h.

Member Function Documentation

Integer RWFunction::ApplyFunction ( const Integer & x ) const

virtual

Applies the trapdoor.

Parameters

x	the message on which the encryption function is applied

Returns: the message x encrypted under the public key

ApplyFunction is a generalization of encryption under a public key cryptosystem. Derived classes must implement it.

Implements TrapdoorFunction.

Definition at line 36 of file rw.cpp.

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void RWFunction::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.

Reimplemented in InvertibleRWFunction.

Definition at line 88 of file rw.cpp.

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void RWFunction::BERDecode ( BufferedTransformation & bt )

Definition at line 22 of file rw.cpp.

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void RWFunction::DEREncode ( BufferedTransformation & bt ) const

Definition at line 29 of file rw.cpp.

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const Integer& RWFunction::GetModulus ( ) const

inline

Definition at line 50 of file rw.h.

bool RWFunction::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.

Reimplemented in InvertibleRWFunction.

Definition at line 81 of file rw.cpp.

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Integer RWFunction::ImageBound ( ) const

inlinevirtual

Returns the maximum size of a message after the trapdoor function is applied.

Returns: the maximum size of a message after the trapdoor function is applied

Derived classes must implement ImageBound().

Implements TrapdoorFunctionBounds.

Definition at line 44 of file rw.h.

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void RWFunction::Initialize ( const Integer & n )

inline

Initialize a Rabin-Williams public key.

Parameters

n	the modulus

Definition at line 31 of file rw.h.

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void RWFunction::Load ( BufferedTransformation & bt )

inlinevirtual

Loads a key from a BufferedTransformation.

Parameters

bt	the source BufferedTransformation

Exceptions

KeyingErr

Load() attempts to read material from a BufferedTransformation. If the material is a key that was generated outside the library, then the following usually applies:

the key should be ASN.1 BER encoded
the key should be a "key info"

"key info" means the key should have an object identifier with an algorthm id, like a subjectPublicKeyInfo.

To read a "raw" key without the "key info", then call the key's BERDecode() method.

Note: Load generally does not check that the key is valid. Call Validate(), if needed.

Reimplemented from CryptoMaterial.

Reimplemented in InvertibleRWFunction.

Definition at line 39 of file rw.h.

Integer RWFunction::PreimageBound ( ) const

inlinevirtual

Returns the maximum size of a message before the trapdoor function is applied.

Returns: the maximum size of a message before the trapdoor function is applied

Derived classes must implement PreimageBound().

Implements TrapdoorFunctionBounds.

Definition at line 43 of file rw.h.

void RWFunction::Save ( BufferedTransformation & bt ) const

inlinevirtual

Saves a key to a BufferedTransformation.

Parameters

bt	the destination BufferedTransformation

Exceptions

NotImplemented

Save() writes the material to a BufferedTransformation.

If the material is a key, then the key is written with ASN.1 DER encoding. The key includes an object identifier with an algorthm id, like a subjectPublicKeyInfo.

A "raw" key without the "key info" can be saved using a key's DEREncode() method.

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

Reimplemented from CryptoMaterial.

Reimplemented in InvertibleRWFunction.

Definition at line 37 of file rw.h.

void RWFunction::SetModulus ( const Integer & n )

inline

Definition at line 51 of file rw.h.

bool RWFunction::Validate	(	RandomNumberGenerator &	rng,
		unsigned int	level
	)		const

virtual

Check this object for errors.

Parameters

rng	a RandomNumberGenerator for objects which use randomized testing
level	the 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.