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

#include <XTS.h>

Inheritance diagram for XTSCommon:

Public Member Functions
virtual	~XTSCommon ()
	Clears all sensitive information and destroys this object.

virtual size_t	keySize () const
	Gets the size of the key for XTS mode. More...

size_t	tweakSize () const
	Gets the maximum supported size for the tweak. More...

size_t	sectorSize () const
	Gets the size of sectors encrypted or decrypted by this class. More...

bool	setSectorSize (size_t size)
	Sets the size of sectors encrypted or decrypted by this class. More...

virtual bool	setKey (const uint8_t *key, size_t len)
	Sets the key to use for XTS mode. More...

bool	setTweak (const uint8_t *tweak, size_t len)
	Sets the tweak value for the current sector to encrypt or decrypt. More...

void	encryptSector (uint8_t output, const uint8_t input)
	Encrypts an entire sector of data. More...

void	decryptSector (uint8_t output, const uint8_t input)
	Decrypts an entire sector of data. More...

void	clear ()
	Clears all security-sensitive state from this XTS object.

Protected Member Functions
	XTSCommon ()
	Constructs an XTS object with a default sector size of 512 bytes.

void	setBlockCiphers (BlockCipher cipher1, BlockCipher cipher2)
	Sets the two block ciphers to use for XTS mode. More...

Friends
class	XTSSingleKeyCommon

Detailed Description

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

References: IEEE Std. 1619-2007, NIST SP 800-38E, a href="http://web.cs.ucdavis.edu/~rogaway/papers/offsets.pdf">XEX.

See also: XTS, XTSSingleKey

Definition at line 30 of file XTS.h.

Member Function Documentation

◆ decryptSector()

void XTSCommon::decryptSector	(	uint8_t *	output,
		const uint8_t *	input
	)

Decrypts an entire sector of data.

Parameters

output	The output buffer to write the plaintext to, which can be the same as input.
input	The input buffer to read the ciphertext from.

The input and output buffers must be at least sectorSize() bytes in length.

See also: encryptSector(), setKey(), setTweak()

Definition at line 215 of file XTS.cpp.

◆ encryptSector()

void XTSCommon::encryptSector	(	uint8_t *	output,
		const uint8_t *	input
	)

Encrypts an entire sector of data.

Parameters

output	The output buffer to write the ciphertext to, which can be the same as input.
input	The input buffer to read the plaintext from.

The input and output buffers must be at least sectorSize() bytes in length.

See also: decryptSector(), setKey(), setTweak()

Definition at line 170 of file XTS.cpp.

◆ keySize()

size_t XTSCommon::keySize ( ) const

virtual

Gets the size of the key for XTS mode.

The key size for XTS mode is twice the size of the underlying block cipher key size.

See also: setKey(), tweakSize()

Reimplemented in XTSSingleKeyCommon.

Definition at line 62 of file XTS.cpp.

◆ sectorSize()

size_t XTSCommon::sectorSize ( ) const

inline

Gets the size of sectors encrypted or decrypted by this class.

The default value is 512 bytes.

See also: setSectorSize()

Definition at line 38 of file XTS.h.

◆ setBlockCiphers()

void XTSCommon::setBlockCiphers	(	BlockCipher *	cipher1,
		BlockCipher *	cipher2
	)

inlineprotected

Sets the two block ciphers to use for XTS mode.

Parameters

cipher1	Points to the first block cipher object, which must be capable of both encryption and decryption.
cipher2	Points to the second block cipher object, which must be capable of both encryption but does not need to be capable of decryption.

Both block ciphers must have a 128-bit block size.

Definition at line 51 of file XTS.h.

◆ setKey()

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

virtual

Sets the key to use for XTS mode.

Parameters

key	Points to the key.
len	The size of the key in bytes which must be twice the size of the underlying block cipher's key size.

Returns: Returns true if the key was set or false if len was incorrect.

This function should be followed by a call to setTweak() to specify the sector-specific tweak.

See also: keySize(), setTweak(), encryptSector()

Reimplemented in XTSSingleKeyCommon.

Definition at line 119 of file XTS.cpp.

◆ setSectorSize()

bool XTSCommon::setSectorSize ( size_t size )

Sets the size of sectors encrypted or decrypted by this class.

Parameters

size	The sector size in bytes, which must be greater than or equal to 16.

Returns: Returns false if size is less than 16.

See also: sectorSize(), encryptSector()

Definition at line 97 of file XTS.cpp.

◆ setTweak()

bool XTSCommon::setTweak	(	const uint8_t *	tweak,
		size_t	len
	)

Sets the tweak value for the current sector to encrypt or decrypt.

Parameters

tweak	Points to the tweak.
len	The length of the tweak which must be less than or equal to 16.

Returns: Returns true if the tweak was set or false if len was incorrect.

If len is less than 16, then the tweak will be zero-padded to 16 bytes.

The tweak is encrypted with the second half of the XTS key to generate the actual tweak value for the sector.

See also: tweakSize(), setKey(), encryptSector()

Definition at line 142 of file XTS.cpp.

◆ tweakSize()

size_t XTSCommon::tweakSize ( ) const

Gets the maximum supported size for the tweak.

This function returns 16, which indicates that any tweak up to 16 bytes in size can be specified via setTweak().

Definition at line 73 of file XTS.cpp.

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

Public Member Functions

Protected Member Functions

Friends

Detailed Description

Member Function Documentation

◆ decryptSector()

◆ encryptSector()

◆ keySize()

◆ sectorSize()

◆ setBlockCiphers()

◆ setKey()

◆ setSectorSize()

◆ setTweak()

◆ tweakSize()