RandomPool Class Reference

Randomness Pool based on AES-256. More...

#include <randpool.h>

Inheritance diagram for RandomPool:

Public Member Functions
	RandomPool ()
	Construct a RandomPool.
bool	CanIncorporateEntropy () const
	Determines if a generator can accept additional entropy.
void	IncorporateEntropy (const byte *input, size_t length)
	Update RNG state with additional unpredictable values.
void	GenerateIntoBufferedTransformation (BufferedTransformation &target, const std::string &channel, lword size)
	Generate random bytes into a BufferedTransformation.
Public Member Functions inherited from RandomNumberGenerator
virtual byte	GenerateByte ()
	Generate new random byte and return it.
virtual unsigned int	GenerateBit ()
	Generate new random bit and return it.
virtual word32	GenerateWord32 (word32 min=0, word32 max=0xffffffffUL)
	Generate a random 32 bit word in the range min to max, inclusive.
virtual void	GenerateBlock (byte *output, size_t size)
	Generate random array of bytes.
virtual void	DiscardBytes (size_t n)
	Generate and discard n bytes.
template<class IT >
void	Shuffle (IT begin, IT end)
	Randomly shuffle the specified array.
Public Member Functions inherited from Algorithm
	Algorithm (bool checkSelfTestStatus=true)
	Interface for all crypto algorithms.
virtual std::string	AlgorithmName () const
	Provides the name of this algorithm.
virtual std::string	AlgorithmProvider () const
	Retrieve the provider of this algorithm.
Public Member Functions inherited from Clonable
virtual Clonable *	Clone () const
	Copies this object.

Detailed Description

Randomness Pool based on AES-256.

RandomPool can be used to generate cryptographic quality pseudorandom bytes after seeding the pool with IncorporateEntropy(). Internally, the generator uses AES-256 to produce the stream. Entropy is stirred in using SHA-256.

RandomPool used to follow the design of randpool in PGP 2.6.x. At version 5.5 RandomPool was redesigned to reduce the risk of reusing random numbers after state rollback, which may occur when running in a virtual machine like VMware or a hosted environment.

You should reseed the generator after a fork() to avoid multiple generators with the same internal state.

If you need the pre-Crypto++ 5.5 generator then use OldRandomPool class. You should migrate away from OldRandomPool at the earliest opportunity.

See also

OldRandomPool

Since

Crypto++ 4.0 (PGP 2.6.x style), Crypto++ 5.5 (AES-256 based)

Definition at line 43 of file randpool.h.

Member Function Documentation

CanIncorporateEntropy()

bool RandomPool::CanIncorporateEntropy ( ) const

inlinevirtual

Determines if a generator can accept additional entropy.

Returns

true if IncorporateEntropy() is implemented

Reimplemented from RandomNumberGenerator.

Definition at line 49 of file randpool.h.

IncorporateEntropy()

void RandomPool::IncorporateEntropy ( const byte * input, size_t length )

virtual

Update RNG state with additional unpredictable values.

Parameters

input	the entropy to add to the generator
length	the size of the input buffer

Exceptions

NotImplemented

A generator may or may not accept additional entropy. Call CanIncorporateEntropy() to test for the ability to use additional entropy.

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

Reimplemented from RandomNumberGenerator.

GenerateIntoBufferedTransformation()

void RandomPool::GenerateIntoBufferedTransformation ( BufferedTransformation & target, const std::string & channel, lword length )

virtual

Generate random bytes into a BufferedTransformation.

Parameters

target	the BufferedTransformation object which receives the bytes
channel	the channel on which the bytes should be pumped
length	the number of bytes to generate

The default implementation calls GenerateBlock() and pumps the result into the DEFAULT_CHANNEL of the target.

All generated values are uniformly distributed over the range specified within the the constraints of a particular generator.

Note

A derived generator must override either GenerateBlock() or GenerateIntoBufferedTransformation(). They can override both, or have one call the other.

Reimplemented from RandomNumberGenerator.

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

• randpool.h