Crypto++  5.6.5
Free C++ class library of cryptographic schemes
Public Member Functions | List of all members
RWFunction Class Reference

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

+ Inheritance 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 IntegerGetModulus () const
 
void SetModulus (const Integer &n)
 
- Public Member Functions inherited from 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 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 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
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

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 Function Documentation

void RWFunction::Initialize ( const Integer n)
inline

Initialize a Rabin-Williams public key.

Parameters
nthe modulus

Definition at line 31 of file rw.h.

void RWFunction::Save ( BufferedTransformation bt) const
inlinevirtual

Saves a key to a BufferedTransformation.

Parameters
btthe 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::Load ( BufferedTransformation bt)
inlinevirtual

Loads a key from a BufferedTransformation.

Parameters
btthe 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::ApplyFunction ( const Integer x) const
virtual

Applies the trapdoor.

Parameters
xthe 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.

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.

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.

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

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.

Reimplemented in InvertibleRWFunction.

Definition at line 73 of file rw.cpp.

bool RWFunction::GetVoidValue ( const char *  name,
const std::type_info &  valueType,
void *  pValue 
) const
virtual

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.

Reimplemented in InvertibleRWFunction.

Definition at line 81 of file rw.cpp.

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.


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