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

#include <SpeckSmall.h>

Inheritance diagram for SpeckSmall:

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

bool	setKey (const uint8_t *key, size_t len)
	Sets the key to use for future encryption and decryption operations. 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 SpeckTiny
	SpeckTiny ()
	Constructs a tiny-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 (small-memory version).

This class differs from the Speck class in that the RAM requirements are vastly reduced. The key schedule is expanded round by round instead of being generated and stored by setKey(). The performance of encryption and decryption is slightly less because of this.

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

The companion SpeckTiny class uses even less RAM but only supports the encryptBlock() operation. Block cipher modes like CTR, EAX, and GCM do not need the decryptBlock() operation, so SpeckTiny may be a better option than SpeckSmall for many applications.

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, SpeckTiny

Definition at line 28 of file SpeckSmall.h.

Constructor & Destructor Documentation

◆ SpeckSmall()

SpeckSmall::SpeckSmall ( )

Constructs a small-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 or decryption.

Definition at line 85 of file SpeckSmall.cpp.

Member Function Documentation

◆ clear()

void SpeckSmall::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 582 of file SpeckSmall.cpp.

◆ decryptBlock()

void SpeckSmall::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.

See also: encryptBlock(), blockSize()

Implements BlockCipher.

Definition at line 261 of file SpeckSmall.cpp.

◆ setKey()

bool SpeckSmall::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 94 of file SpeckSmall.cpp.

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

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ SpeckSmall()

Member Function Documentation

◆ clear()

◆ decryptBlock()

◆ setKey()