KeyDerivationFunction Class Reference

Interface for key derivation functions. More...

#include <cryptlib.h>

Inheritance diagram for KeyDerivationFunction:

Public Member Functions
virtual std::string	AlgorithmName () const =0
	Provides the name of this algorithm.
virtual size_t	MinDerivedKeyLength () const
	Determine minimum number of bytes.
virtual size_t	MaxDerivedKeyLength () const
	Determine maximum number of bytes.
virtual size_t	GetValidDerivedLength (size_t keylength) const =0
	Returns a valid key length for the derivation function.
virtual bool	IsValidDerivedLength (size_t keylength) const
	Returns whether keylength is a valid key length.
virtual size_t	DeriveKey (byte *derived, size_t derivedLen, const byte *secret, size_t secretLen, const NameValuePairs &params=g_nullNameValuePairs) const =0
	Derive a key from a seed.
virtual void	SetParameters (const NameValuePairs &params)
	Set or change parameters.
Public Member Functions inherited from Algorithm
	Algorithm (bool checkSelfTestStatus=true)
	Interface for all crypto algorithms.
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

Interface for key derivation functions.

Since

Crypto++ 7.0

See also

KeyDerivationFunction on the Crypto++ wiki

Definition at line 1527 of file cryptlib.h.

Constructor & Destructor Documentation

~KeyDerivationFunction()

virtual KeyDerivationFunction::~KeyDerivationFunction ( )

inlinevirtual

Definition at line 1530 of file cryptlib.h.

Member Function Documentation

AlgorithmName()

virtual std::string KeyDerivationFunction::AlgorithmName ( ) const

pure virtual

Provides the name of this algorithm.

Returns

the standard algorithm name

Reimplemented from Algorithm.

Implemented in HKDF< T >, PKCS5_PBKDF1< T >, PKCS5_PBKDF2_HMAC< T >, PKCS12_PBKDF< T >, and Scrypt.

MinDerivedKeyLength()

virtual size_t KeyDerivationFunction::MinDerivedKeyLength ( ) const

virtual

Determine minimum number of bytes.

Returns

Minimum number of bytes which can be derived

MaxDerivedKeyLength()

virtual size_t KeyDerivationFunction::MaxDerivedKeyLength ( ) const

virtual

Determine maximum number of bytes.

Returns

Maximum number of bytes which can be derived

Reimplemented in HKDF< T >, PKCS5_PBKDF1< T >, PKCS5_PBKDF2_HMAC< T >, PKCS12_PBKDF< T >, and Scrypt.

GetValidDerivedLength()

virtual size_t KeyDerivationFunction::GetValidDerivedLength ( size_t keylength ) const

pure virtual

Returns a valid key length for the derivation function.

Parameters

keylength

the size of the derived key, in bytes

Returns

the valid key length, in bytes

Implemented in HKDF< T >, PKCS5_PBKDF1< T >, PKCS5_PBKDF2_HMAC< T >, PKCS12_PBKDF< T >, and Scrypt.

IsValidDerivedLength()

virtual bool KeyDerivationFunction::IsValidDerivedLength ( size_t keylength ) const

inlinevirtual

Returns whether keylength is a valid key length.

Parameters

keylength

the requested keylength

Returns

true if the derived keylength is valid, false otherwise

Internally the function calls GetValidKeyLength()

Definition at line 1553 of file cryptlib.h.

DeriveKey()

virtual size_t KeyDerivationFunction::DeriveKey ( byte * derived, size_t derivedLen, const byte * secret, size_t secretLen, const NameValuePairs & params = g_nullNameValuePairs ) const

pure virtual

Derive a key from a seed.

Parameters

derived	the derived output buffer
derivedLen	the size of the derived buffer, in bytes
secret	the seed input buffer
secretLen	the size of the secret buffer, in bytes
params	additional initialization parameters to configure this object

Returns

the number of iterations performed

Exceptions

InvalidDerivedKeyLength

if derivedLen is invalid for the scheme

DeriveKey() provides a standard interface to derive a key from a secret seed and other parameters. Each class that derives from KeyDerivationFunction provides an overload that accepts most parameters used by the derivation function.

the number of iterations performed by DeriveKey() may be 1. For example, a scheme like HKDF does not use the iteration count so it returns 1.

Implemented in HKDF< T >, Scrypt, PKCS5_PBKDF1< T >, PKCS5_PBKDF2_HMAC< T >, and PKCS12_PBKDF< T >.

SetParameters()

virtual void KeyDerivationFunction::SetParameters ( const NameValuePairs & params )

virtual

Set or change parameters.

Parameters

params

additional initialization parameters to configure this object

SetParameters() is useful for setting common parameters when an object is reused. Some derivation function classes may choose to implement it.

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

• cryptlib.h