DES Class Reference

#include <DES.h>

Public Member Functions
void	encrypt (void *out, const void *in, const void *key)
	decrypt a block with DES More...
void	decrypt (void *out, const void *in, const uint8_t *key)
	encrypt a block with DES More...
void	tripleEncrypt (void *out, void *in, const void *key)
	encrypt a block with Tripple-DES More...
void	tripleDecrypt (void *out, void *in, const uint8_t *key)
	decrypt a block with Tripple-DES More...
	DES ()
	DES constructor. More...
void	init (const void *m_key, unsigned long long int IVCl)
	initiallize the key and IVC and IV array More...
void	init (const void *m_key)
	initiallize the key More...
void	change_key (const void *m_key)
	change the key for DEs and 3DES More...
void	set_IV (unsigned long long int IVCl)
void	get_IV (byte *out)
unsigned long long int	get_IV_int ()
void	iv_inc ()
byte *	get_key ()
	getter method for key More...
int	get_size ()
	getter method for size More...
void	set_size (int sizel)
void	calc_size_n_pad (int p_size)
	calculates the size of the plaintext and the padding More...
void	padPlaintext (void *in, byte *out)
	pads the plaintext More...
bool	CheckPad (byte *in, int size)
	check the if the padding is correct More...
void	tdesCbcEncipher (byte *in, byte *out)
	the main encrypt 3DES with IV function More...
void	tdesCbcDecipher (byte *in, byte *out)
	the main decrypt 3DES with IV function More...
void	printArray (byte output[], bool p_pad=true)
void	printArray (byte output[], int sizel)
void	do_3des_encrypt (byte *plain, int size_p, byte *cipher, const void *key, bool inc=false)
void	do_3des_decrypt (byte *cipher, int size_c, byte *plain, const void *key, unsigned long long int ivl)
double	millis ()

Private Member Functions
void	permute (const uint8_t *ptable, const uint8_t *in, uint8_t *out)
void	changeendian32 (uint32_t *a)
void	shiftkey (uint8_t *key)
void	shiftkey_inv (uint8_t *key)
uint64_t	splitin6bitwords (uint64_t a)
uint8_t	substitute (uint8_t a, uint8_t *sbp)
uint32_t	des_f (uint32_t r, uint8_t *kr)

Private Attributes
byte	key [24]
unsigned long long int	IVC
byte	iv [8]
int	pad
int	size
timeval	tv
byte	arr_pad [7]

Detailed Description

Examples:

DesedeCBC-easy.cpp, DesedeCBCexample.ino, DESexample.cpp, and DESexample.ino.

Constructor & Destructor Documentation

DES::DES

(

)

DES constructor.

This function initialized an instance of DES

Member Function Documentation

void DES::encrypt	(	void *	out,
		const void *	in,
		const void *	key
	)

decrypt a block with DES

This function decrypts a block of 64 bits (8 bytes) with the DES algorithm. Key expansion is done automatically. The key is 64 bits long, but note that only 56 bits are used (the LSB of each byte is dropped). The input and output blocks may overlap.

Parameters

out	pointer to the block (64 bit = 8 byte) where the plaintext is written to
in	pointer to the block (64 bit = 8 byte) where the ciphertext is read from
key	pointer to the key (64 bit = 8 byte)

Examples:

DESexample.cpp, and DESexample.ino.

void DES::decrypt	(	void *	out,
		const void *	in,
		const uint8_t *	key
	)

encrypt a block with DES

This function encrypts a block of 64 bits (8 bytes) with the DES algorithm. Key expansion is done automatically. The key is 64 bits long, but note that only 56 bits are used (the LSB of each byte is dropped). The input and output blocks may overlap.

Parameters

out	pointer to the block (64 bit = 8 byte) where the ciphertext is written to
in	pointer to the block (64 bit = 8 byte) where the plaintext is read from
key	pointer to the key (64 bit = 8 byte)

Examples:

DESexample.cpp, and DESexample.ino.

void DES::tripleEncrypt	(	void *	out,
		void *	in,
		const void *	key
	)

encrypt a block with Tripple-DES

This function encrypts a block of 64 bits (8 bytes) with the Tripple-DES (EDE) algorithm. Key expansion is done automatically. The key is 192 bits long, but note that only 178 bits are used (the LSB of each byte is dropped). The input and output blocks may overlap.

Parameters

out	pointer to the block (64 bit = 8 byte) where the ciphertext is written to
in	pointer to the block (64 bit = 8 byte) where the plaintext is read from
key	pointer to the key (192 bit = 24 byte)

Examples:

DESexample.cpp, and DESexample.ino.

void DES::tripleDecrypt	(	void *	out,
		void *	in,
		const uint8_t *	key
	)

decrypt a block with Tripple-DES

This function decrypts a block of 64 bits (8 bytes) with the Tripple-DES (EDE) algorithm. Key expansion is done automatically. The key is 192 bits long, but note that only 178 bits are used (the LSB of each byte is dropped). The input and output blocks may overlap.

Parameters

out	pointer to the block (64 bit = 8 byte) where the plaintext is written to
in	pointer to the block (64 bit = 8 byte) where the ciphertext is read from
key	pointer to the key (192 bit = 24 byte)

Examples:

DESexample.cpp, and DESexample.ino.

void DES::init	(	const void *	m_key,
		unsigned long long int	IVCl
	)

initiallize the key and IVC and IV array

This function initialized the basic variables needed for 3DES

Parameters

m_key	(64 bit = 8 byte)
IVCl	int or hex value of iv , ex. 0x0000000000000001

Examples:

DesedeCBC-easy.cpp, and DesedeCBCexample.ino.

void DES::init

(

const void *

m_key

)

initiallize the key

This function initialized the basic variables needed for DES

Parameters

m_key

(64 bit = 8 byte)

void DES::change_key

(

const void *

m_key

)

change the key for DEs and 3DES

This function changes the key variable needed for DES

Parameters

m_key

(64 bit = 8 byte)

void DES::set_IV

(

unsigned long long int

IVCl

)

void DES::get_IV

(

byte *

out

)

Getter method for IV

This function return the IV

Parameters

*out	byte pointer that gets the IV.

Returns

none, the IV is writed to the out pointer.

unsigned long long int DES::get_IV_int

(

)

Getter method for IV

This function return the IV

Parameters

out	byte pointer that gets the IV.

Returns

none, the IV is writed to the out pointer.

Examples:

DesedeCBC-easy.cpp.

void DES::iv_inc

(

)

Examples:

DesedeCBCexample.ino.

DES::get_key

(

)

getter method for key

This function return the key

Returns

returns the key

DES::get_size

(

)

getter method for size

This function return the size

Returns

returns the size

Examples:

DesedeCBCexample.ino.

void DES::set_size

(

int

sizel

)

Setter method for size

This function sets the size of the plaintext+pad

DES::calc_size_n_pad

(

int

p_size

)

calculates the size of the plaintext and the padding

calculates the size of theplaintext with the padding and the size of the padding needed. Moreover it stores them in their variables.

Parameters

p_size

the size of the byte array ex sizeof(plaintext)

Examples:

DesedeCBCexample.ino.

DES::padPlaintext	(	void *	in,
		byte *	out
	)

pads the plaintext

This function pads the plaintext and returns an char array with the plaintext and the padding in order for the plaintext to be compatible with 8bit size blocks required by 3DES

Parameters

in	the string of the plaintext in a byte array
out	the string of the padded plaintext in a byte array

Examples:

DesedeCBCexample.ino.

DES::CheckPad	(	byte *	in,
		int	size
	)

check the if the padding is correct

This functions checks the padding of the plaintext.

Parameters

*in	the string of the plaintext in a byte array
size	the size of the string

Returns

true if correct / false if not

Examples:

DesedeCBCexample.ino.

DES::tdesCbcEncipher	(	byte *	in,
		byte *	out
	)

the main encrypt 3DES with IV function

This function uses the IV to xor (^) the first block of the string and encrypts it using tripleEncrypt function

Parameters

in	the string of the plaintext in a byte array
out	the string of the ciphertext in a byte array

Examples:

DesedeCBCexample.ino.

DES::tdesCbcDecipher	(	byte *	in,
		byte *	out
	)

the main decrypt 3DES with IV function

This function if the reverse of the tdesCbcEncipher function. used the IV and then the tripleDecrypt

Parameters

in	the string of the ciphertext in a byte array
out	the string of the plaintext in a byte array

Examples:

DesedeCBCexample.ino.

void DES::printArray	(	byte	output[],
		bool	p_pad = true
	)

void DES::printArray	(	byte	output[],
		int	sizel
	)

Prints the array given.

This function prints the given array in Hexadecimal.

Parameters

output[]	the string of the text in a byte array
sizel	the size of the array.

void DES::do_3des_encrypt	(	byte *	plain,
		int	size_p,
		byte *	cipher,
		const void *	key,
		bool	inc = false
	)

User friendly implementation of AES-CBC encryption.

Parameters

*plain	pointer to the plaintext
size_p	size of the plaintext
*cipher	pointer to the ciphertext
*key	pointer to the key that will be used.
inc	optional parameter to automaticaly increase IV

Note

The key will be stored in class variable.

Examples:

DesedeCBC-easy.cpp.

void DES::do_3des_decrypt	(	byte *	cipher,
		int	size_c,
		byte *	plain,
		const void *	key,
		unsigned long long int	ivl
	)

User friendly implementation of AES-CBC decryption.

Parameters

*cipher	pointer to the ciphertext
size_c	size of the ciphertext
*plain	pointer to the plaintext
*key	pointer to the key that will be used.
ivl	the initialization vector IV that will be used for decryption.

Note

The key will be stored in class variable.

Examples:

DesedeCBC-easy.cpp.

double DES::millis

(

)

used in linux in order to retrieve the time in milliseconds.

Returns

returns the milliseconds in a double format.

Examples:

DesedeCBC-easy.cpp, and DESexample.cpp.

void DES::permute ( const uint8_t *  ptable, const uint8_t *  in, uint8_t *  out  )

private

Permutation for DES.

Parameters

*ptable	the permutaion table to be used.
*in	the pointer that holds the data before the permutations.
*out	the pointer that holds the data after the permutation.

Returns

none, the output is inside the out pointer

void DES::changeendian32 ( uint32_t *  a )

private

change endian form.

Parameters

*a	the byte to change endian

void DES::shiftkey ( uint8_t *  key )

inlineprivate

used to shift the key. Used the shiftkey_permtab permutation table.

Parameters

*key	the key to be shifted.

void DES::shiftkey_inv ( uint8_t *  key )

inlineprivate

used to shift the key back. Used the shiftkeyinv_permtab permutation table.

Parameters

*key	the key to be shifted.

uint64_t DES::splitin6bitwords ( uint64_t  a )

inlineprivate

splits in 6 bit words

Parameters

a	uint64_t size that will be slitted, permuted and returned.

Returns

the permuted a.

uint8_t DES::substitute ( uint8_t  a, uint8_t *  sbp  )

inlineprivate

main function for the substitutions

Parameters

a	array position
*sbp	array to read byte from

Returns

the substituted byte.

uint32_t DES::des_f ( uint32_t  r, uint8_t *  kr  )

private

Primary function of DES. Used in encryption and decryption process.

Parameters

r	unsigned intefer 32 bit, Data to be permuted.
kr	pointer of unsigned integers 8 bit, Data to be XOR with r after permutation

Returns

Member Data Documentation

byte DES::key[24]

private

holds the key for the encryption

unsigned long long int DES::IVC

private

holds the initialization vector counter in numerical format.

byte DES::iv[8]

private

holds the initialization vector that will be used in the cipher.

int DES::pad

private

holds the size of the padding.

DES::size

private

hold the size of the plaintext to be ciphered

and pad equal

timeval DES::tv

private

holds the time value on linux

byte DES::arr_pad[7]

private

holds the hexadecimal padding values, initialisation in the constructor