Speck block cipher with a 128-bit block size (low-memory version). More...

#include <SpeckLowMemory.h>

Inheritance diagram for SpeckLowMemory:

Public Member Functions
	SpeckLowMemory ()
	Constructs a low-memory Speck block cipher with no initial key. More...

size_t	blockSize () const
	Size of a single block processed by this cipher, in bytes. More...

size_t	keySize () const
	Default size of the key for this block 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...

void	encryptBlock (uint8_t output, const uint8_t input)
	Encrypts a single block using this cipher. More...

void	decryptBlock (uint8_t output, const uint8_t input)
	Decrypts a single block using this cipher. More...

void	clear ()
	Clears all security-sensitive state from this block cipher. More...

Public Member Functions inherited from BlockCipher
	BlockCipher ()
	Constructs a block cipher.

virtual	~BlockCipher ()
	Destroys this block cipher object. More...

Detailed Description

Speck block cipher with a 128-bit block size (low-memory version).

This class differs from the Speck class in the following ways:

RAM requirements are vastly reduced. The key (up to 256 bits) is stored directly and then expanded to the full key schedule round by round. The setKey() method is very fast because of this.
Performance of encryptBlock() is slower than for Speck due to expanding the key on the fly rather than ahead of time.
The decryptBlock() function is not supported, which means that CBC mode cannot be used but the CTR, CFB, OFB, and GCM modes can be used.

This class is useful when RAM is at a premium, CBC mode is not required, and reduced encryption performance is not a hindrance to the application. Even though the performance of encryptBlock() is reduced, this class is still faster than AES with equivalent key sizes.

See the documentation for the Speck class for more information on the Speck family of block ciphers.

References: https://en.wikipedia.org/wiki/Speck_%28cipher%29, http://eprint.iacr.org/2013/404

See Also: Speck

Definition at line 28 of file SpeckLowMemory.h.

Constructor & Destructor Documentation

SpeckLowMemory::SpeckLowMemory ( )

Constructs a low-memory Speck block cipher with no initial key.

This constructor must be followed by a call to setKey() before the block cipher can be used for encryption.

Definition at line 73 of file SpeckLowMemory.cpp.

Member Function Documentation

size_t SpeckLowMemory::blockSize ( ) const

virtual

Size of a single block processed by this cipher, in bytes.

Returns: Returns the size of a block in bytes.

See Also: keySize(), encryptBlock()

Implements BlockCipher.

Definition at line 83 of file SpeckLowMemory.cpp.

void SpeckLowMemory::clear ( )

virtual

Clears all security-sensitive state from this block cipher.

Security-sensitive information includes key schedules and any temporary state that is used by encryptBlock() or decryptBlock() which is stored in the object itself.

See Also: setKey(), encryptBlock(), decryptBlock()

Implements BlockCipher.

Definition at line 542 of file SpeckLowMemory.cpp.

void SpeckLowMemory::decryptBlock	(	uint8_t *	output,
		const uint8_t *	input
	)

virtual

Decrypts a single block using this cipher.

Parameters

output	The output buffer to put the plaintext into. Must be at least blockSize() bytes in length.
input	The input buffer to read the ciphertext from which is allowed to overlap with output. Must be at least blockSize() bytes in length.

Note: This function is not supported for SpeckLowMemory, which means that CBC mode cannot be used but that the CTR, CFB, OFB, and GCM modes can be used.

Implements BlockCipher.

Definition at line 537 of file SpeckLowMemory.cpp.

void SpeckLowMemory::encryptBlock	(	uint8_t *	output,
		const uint8_t *	input
	)

virtual

Encrypts a single block using this cipher.

Parameters

output	The output buffer to put the ciphertext into. Must be at least blockSize() bytes in length.
input	The input buffer to read the plaintext from which is allowed to overlap with output. Must be at least blockSize() bytes in length.

See Also: decryptBlock(), blockSize()

Implements BlockCipher.

Definition at line 153 of file SpeckLowMemory.cpp.

size_t SpeckLowMemory::keySize ( ) const

virtual

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

This value indicates the default, or recommended, size for the key.

See Also: setKey(), blockSize()

Implements BlockCipher.

Definition at line 88 of file SpeckLowMemory.cpp.

bool SpeckLowMemory::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.

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.

See Also: keySize(), clear()

Implements BlockCipher.

Definition at line 106 of file SpeckLowMemory.cpp.

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

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation