AES block cipher with 128-bit keys and reduced memory usage. More...

#include <AES.h>

Inheritance diagram for AESSmall128:

Public Member Functions
	AESSmall128 ()
	Constructs an AES 128-bit 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 AESTiny128
	AESTiny128 ()
	Constructs an AES 128-bit block cipher with no initial key. More...

size_t	blockSize () const
	Size of an AES block in bytes. More...

size_t	keySize () const
	Size of a 128-bit AES key in bytes. More...

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

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

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

Detailed Description

AES block cipher with 128-bit keys and reduced memory usage.

This class differs from the AES128 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.

The companion AESTiny128 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 AESTiny128 may be a better option than AESSmall128 for many applications.

See also: AESTiny128, AES128

Definition at line 173 of file AES.h.

Constructor & Destructor Documentation

◆ AESSmall128()

AESSmall128::AESSmall128 ( )

Constructs an AES 128-bit 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 271 of file AES128.cpp.

Member Function Documentation

◆ clear()

void AESSmall128::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()

Reimplemented from AESTiny128.

Definition at line 350 of file AES128.cpp.

◆ decryptBlock()

void AESSmall128::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()

Reimplemented from AESTiny128.

Definition at line 306 of file AES128.cpp.

◆ setKey()

bool AESSmall128::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()

Reimplemented from AESTiny128.

Definition at line 280 of file AES128.cpp.

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

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ AESSmall128()

Member Function Documentation

◆ clear()

◆ decryptBlock()

◆ setKey()