OFBCommon Class Reference

Concrete base class to assist with implementing OFB for 128-bit block ciphers. More...

#include <OFB.h>

Inheritance diagram for OFBCommon:

Public Member Functions
virtual	~OFBCommon ()
	Destroys this cipher object after clearing sensitive information.
size_t	keySize () const
	Default size of the key for this cipher, in bytes. More...
size_t	ivSize () const
	Size of the initialization vector for this cipher, in bytes. More...
bool	setKey (const uint8_t *key, size_t len)
	Sets the key to use for future encryption and decryption operations. More...
bool	setIV (const uint8_t *iv, size_t len)
	Sets the initialization vector to use for future encryption and decryption operations. More...
void	encrypt (uint8_t *output, const uint8_t *input, size_t len)
	Encrypts an input buffer and writes the ciphertext to an output buffer. More...
void	decrypt (uint8_t *output, const uint8_t *input, size_t len)
	Decrypts an input buffer and writes the plaintext to an output buffer. More...
void	clear ()
	Clears all security-sensitive state from this cipher. More...
Public Member Functions inherited from Cipher
	Cipher ()
	Constructs a new cipher object.
virtual	~Cipher ()
	Destroys this cipher object. More...

Protected Member Functions
	OFBCommon ()
	Constructs a new cipher in OFB mode. More...
void	setBlockCipher (BlockCipher *cipher)
	Sets the block cipher to use for this OFB object. More...

Detailed Description

Concrete base class to assist with implementing OFB for 128-bit block ciphers.

Reference: http://en.wikipedia.org/wiki/Block_cipher_mode_of_operation

See also

OFB

Definition at line 29 of file OFB.h.

Constructor & Destructor Documentation

OFBCommon()

OFBCommon::OFBCommon ( )

protected

Constructs a new cipher in OFB mode.

This constructor should be followed by a call to setBlockCipher().

Definition at line 42 of file OFB.cpp.

Member Function Documentation

clear()

void OFBCommon::clear ( )

virtual

Clears all security-sensitive state from this cipher.

Security-sensitive information includes key schedules, initialization vectors, and any temporary state that is used by encrypt() or decrypt() which is stored in the cipher itself.

Implements Cipher.

Definition at line 113 of file OFB.cpp.

decrypt()

void OFBCommon::decrypt ( uint8_t *  output, const uint8_t *  input, size_t  len  )

virtual

Decrypts an input buffer and writes the plaintext to an output buffer.

Parameters

output	The output buffer to write to, which may be the same buffer as input. The output buffer must have at least as many bytes as the input buffer.
input	The input buffer to read from.
len	The number of bytes to decrypt.

The decrypt() function can be called multiple times with different regions of the ciphertext data.

See also

encrypt()

Implements Cipher.

Definition at line 108 of file OFB.cpp.

encrypt()

void OFBCommon::encrypt ( uint8_t *  output, const uint8_t *  input, size_t  len  )

virtual

Encrypts an input buffer and writes the ciphertext to an output buffer.

Parameters

output	The output buffer to write to, which may be the same buffer as input. The output buffer must have at least as many bytes as the input buffer.
input	The input buffer to read from.
len	The number of bytes to encrypt.

The encrypt() function can be called multiple times with different regions of the plaintext data.

See also

decrypt()

Implements Cipher.

Definition at line 85 of file OFB.cpp.

ivSize()

size_t OFBCommon::ivSize ( ) const

virtual

Size of the initialization vector for this cipher, in bytes.

If the cipher does not need an initialization vector, this function will return zero.

Implements Cipher.

Definition at line 61 of file OFB.cpp.

keySize()

size_t OFBCommon::keySize ( ) const

virtual

Default size of the key for this cipher, in bytes.

If the cipher supports variable-sized keys, keySize() indicates the default or recommended key size. The cipher may support other key sizes.

See also

setKey(), ivSize()

Implements Cipher.

Definition at line 56 of file OFB.cpp.

setBlockCipher()

void OFBCommon::setBlockCipher ( BlockCipher *  cipher )

inlineprotected

Sets the block cipher to use for this OFB object.

Parameters

cipher

The block cipher to use to implement OFB mode, which must have a block size of 16 bytes (128 bits).

Definition at line 47 of file OFB.h.

setIV()

bool OFBCommon::setIV ( const uint8_t *  iv, size_t  len  )

virtual

Sets the initialization vector to use for future encryption and decryption operations.

Parameters

iv	The initialization vector to use.
len	The length of the initialization vector in bytes.

Returns

Returns false if the length is not supported.

Initialization vectors should be set before the first call to encrypt() or decrypt() after a setKey() call. If the initialization vector is changed after encryption or decryption begins, then the behaviour is undefined.

Note

The IV is not encoded into the output stream by encrypt(). The caller is responsible for communicating the IV to the other party.

See also

ivSize()

Implements Cipher.

Definition at line 76 of file OFB.cpp.

setKey()

bool OFBCommon::setKey ( const uint8_t *  key, size_t  len  )

virtual

Sets the key to use for future encryption and decryption operations.

Parameters

key	The key to use.
len	The length of the key in bytes.

Returns

Returns false if the key length is not supported, or the key is somehow "weak" and unusable by this cipher.

Use clear() or the destructor to remove the key and any other sensitive data from the object once encryption or decryption is complete.

Calling setKey() resets the cipher. Any temporary data that was being retained for encrypting partial blocks will be abandoned.

See also

keySize(), clear()

Implements Cipher.

Definition at line 66 of file OFB.cpp.

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

• OFB.h
• OFB.cpp