des.h File Reference

The des library, a software library dedicated to the Data Encryption Standard (DES). More...

#include <stdint.h>
#include <inttypes.h>

Go to the source code of this file.

Functions
int	hamming_weight (uint64_t val)
	Returns the Hamming weight of a 64 bits word.
int	hamming_distance (uint64_t val1, uint64_t val2)
	Returns the Hamming distance between two 64 bits words.
uint64_t	des_ip (uint64_t val)
	Initial permutation (64 to 64 bits).
uint64_t	des_n_ip (uint64_t val)
	Inverse of initial permutation (64 to 64 bits).
uint64_t	des_fp (uint64_t val)
	Final permutation (64 to 64 bits).
uint64_t	des_n_fp (uint64_t val)
	Inverse of final permutation (64 to 64 bits).
uint64_t	des_e (uint64_t val)
	E expansion - permutation (32 to 48 bits).
uint64_t	des_n_e (uint64_t val)
	Inverse of E expansion - permutation (48 to 32 bits).
uint64_t	des_p (uint64_t val)
	P permutation (32 to 32 bits).
uint64_t	des_n_p (uint64_t val)
	Inverse of P permutation (32 to 32 bits).
uint64_t	des_pc1 (uint64_t val)
	PC1 permutation - selection (64 to 56 bits).
uint64_t	des_set_parity_bits (uint64_t val)
	Computes the 8 parity bits of a 64 bits word.
uint64_t	des_n_pc1 (uint64_t val)
	Inverse of PC1 permutation - selection (56 to 64 bits).
uint64_t	des_pc2 (uint64_t val)
	PC2 permutation - selection (56 to 48 bits).
uint64_t	des_n_pc2 (uint64_t val)
	Inverse of PC2 permutation - selection (48 to 56 bits).
uint64_t	des_sbox (int sbox, uint64_t val)
	Single SBox computation (6 to 4 bits).
uint64_t	des_sboxes (uint64_t val)
	All SBoxes computation (48 to 32 bits).
uint64_t	des_right_half (uint64_t val)
	Returns the 32 bits right half of a 64 bits word.
uint64_t	des_left_half (uint64_t val)
	Returns the 32 bits left half of a 64 bits word.
uint64_t	des_ls (uint64_t val)
	Applies the left shift rotation of the standard (56 to 56 bits).
uint64_t	des_rs (uint64_t val)
	Applies the right shift rotation of the standard (56 to 56 bits).
uint64_t	des_f (uint64_t rk, uint64_t val)
	The F function of the standard (48+32 bits to 32 bits).
void	des_ks (uint64_t *ks, uint64_t val)
	Computes the whole key schedule from a 64 bits secret key and stores the sixteen 48 bits round keys in an array.
uint64_t	des_enc (uint64_t *ks, uint64_t val)
	Enciphers a 64 bits plaintext with a pre-computed key schedule.
uint64_t	des_dec (uint64_t *ks, uint64_t val)
	Deciphers a 64 bits plaintext with a pre-computed key schedule.
int	des_check (void)
	A functional verification of the DES implementation.

Variables
uint8_t	left_shifts [16]
	Number of left shifts per round.

Detailed Description

The des library, a software library dedicated to the Data Encryption Standard (DES).

Author

Renaud Pacalet, renau.nosp@m.d.pa.nosp@m.calet.nosp@m.@tel.nosp@m.ecom-.nosp@m.pari.nosp@m.s.fr

Date

2009-07-08

Attention

• Most functions of the library check their input parameters and issue warnings or errors when they carry illegal values. Warnings are printed on the standard error output. Errors are also printed on the standard error output and the program exits with a -1 exit status.
• The library uses a single data type to represent all the data of the DES standard: uint64_t. It is a 64 bits unsigned integer.
• Data are always right aligned: when the data width is less than 64 bits, the meaningful bits are always the rightmost bits of the uint64_t.

Function Documentation

hamming_weight()

int hamming_weight

(

uint64_t

val

)

Returns the Hamming weight of a 64 bits word.

Note: the input's width can be anything between 0 and 64, as long as the unused bits are all zeroes.

Returns

The Hamming weight of the input as a 64 bits uint64_t.

Parameters

val	The 64 bits input.

hamming_distance()

int hamming_distance	(	uint64_t	val1,
		uint64_t	val2
	)

Returns the Hamming distance between two 64 bits words.

Note: the width of the inputs can be anything between 0 and 64, as long as they are the same, aligned and that the unused bits are all zeroes.

Returns

The Hamming distance between the two inputs as a 64 bits uint64_t.

Parameters

val1	The first 64 bits input.
val2	The second 64 bits input.

des_ip()

uint64_t des_ip

(

uint64_t

val

)

Initial permutation (64 to 64 bits).

Same as des_n_fp().

Returns

The permutated input as a 64 bits uint64_t.

Parameters

val	The 64 bits input.

des_n_ip()

uint64_t des_n_ip

(

uint64_t

val

)

Inverse of initial permutation (64 to 64 bits).

Same as des_fp().

Returns

The permutated input as a 64 bits uint64_t.

Parameters

val	64 bits input.

des_fp()

uint64_t des_fp

(

uint64_t

val

)

Final permutation (64 to 64 bits).

Inverse of initial permutation, same as des_n_ip().

Returns

The permutated input as a 64 bits uint64_t.

Parameters

val	64 bits input.

des_n_fp()

uint64_t des_n_fp

(

uint64_t

val

)

Inverse of final permutation (64 to 64 bits).

Same as des_ip().

Returns

The permutated input as a 64 bits uint64_t.

Parameters

val	64 bits input.

des_e()

uint64_t des_e

(

uint64_t

val

)

E expansion - permutation (32 to 48 bits).

Returns

The expanded and permutated input as a 48 bits uint64_t.

Parameters

val	32 bits input.

des_n_e()

uint64_t des_n_e

(

uint64_t

val

)

Inverse of E expansion - permutation (48 to 32 bits).

Duplicated bits must have the same value. If they do not, an error is raised.

Returns

The permutated and selected input as a 32 bits uint64_t.

Parameters

val	48 bits input.

des_p()

uint64_t des_p

(

uint64_t

val

)

P permutation (32 to 32 bits).

Returns

The permutated input as a 32 bits uint64_t.

Parameters

val	32 bits input.

des_n_p()

uint64_t des_n_p

(

uint64_t

val

)

Inverse of P permutation (32 to 32 bits).

Returns

The permutated input as a 32 bits uint64_t.

Parameters

val	32 bits input.

des_pc1()

uint64_t des_pc1

(

uint64_t

val

)

PC1 permutation - selection (64 to 56 bits).

No parity check.

Returns

The permutated and selected input as a 56 bits uint64_t.

Parameters

val	64 bits input.

des_set_parity_bits()

uint64_t des_set_parity_bits

(

uint64_t

val

)

Computes the 8 parity bits of a 64 bits word.

Parity bits are the rightmost bit of each byte. Once computed, the number of set bits of each byte is odd, as specified in the DES standard.

Returns

The input with odd parity bits, as a 64 bits uint64_t.

Parameters

val	64 bits input.

des_n_pc1()

uint64_t des_n_pc1

(

uint64_t

val

)

Inverse of PC1 permutation - selection (56 to 64 bits).

Parity bits are computed.

Returns

The permutated and expanded input as a 64 bits uint64_t.

Parameters

val	56 bits input.

des_pc2()

uint64_t des_pc2

(

uint64_t

val

)

PC2 permutation - selection (56 to 48 bits).

Returns

The permutated and selected input as a 48 bits uint64_t.

Parameters

val	56 bits input.

des_n_pc2()

uint64_t des_n_pc2

(

uint64_t

val

)

Inverse of PC2 permutation - selection (48 to 56 bits).

Missing bits are set to 0.

Returns

The permutated and expanded input as a 56 bits uint64_t.

Parameters

val	48 bits input.

des_sbox()

uint64_t des_sbox	(	int	sbox,
		uint64_t	val
	)

Single SBox computation (6 to 4 bits).

Returns

The 4 bits output of SBox number sbox corresponding to the 6 bits input, as a 4 bits uint64_t.

Parameters

sbox	SBox number, from 1 to 8.
val	6 bits input.

des_sboxes()

uint64_t des_sboxes

(

uint64_t

val

)

All SBoxes computation (48 to 32 bits).

Returns

The 32 bits output of all SBoxes corresponding to the 48 bits input, as a 32 bits uint64_t.

Parameters

val	48 bits input.

des_right_half()

uint64_t des_right_half

(

uint64_t

val

)

Returns the 32 bits right half of a 64 bits word.

Returns

The 32 bits right half of a 64 bits word, as a 32 bits uint64_t.

Parameters

val	64 bits input.

des_left_half()

uint64_t des_left_half

(

uint64_t

val

)

Returns the 32 bits left half of a 64 bits word.

Returns

The 32 bits left half of a 64 bits word, as a 32 bits uint64_t.

Parameters

val	64 bits input.

des_ls()

uint64_t des_ls

(

uint64_t

val

)

Applies the left shift rotation of the standard (56 to 56 bits).

Returns

The rotated input, as a 56 bits uint64_t.

Parameters

val	56 bits input.

des_rs()

uint64_t des_rs

(

uint64_t

val

)

Applies the right shift rotation of the standard (56 to 56 bits).

Returns

The rotated input, as a 56 bits uint64_t.

Parameters

val	56 bits input.

des_f()

uint64_t des_f	(	uint64_t	rk,
		uint64_t	val
	)

The F function of the standard (48+32 bits to 32 bits).

Returns

The transformed input, as a 32 bits uint64_t.

Parameters

rk	48 bits round key.
val	32 bits data input.

des_ks()

void des_ks	(	uint64_t *	ks,
		uint64_t	val
	)

Computes the whole key schedule from a 64 bits secret key and stores the sixteen 48 bits round keys in an array.

The sixteen 48 bits round keys are returned in the array passed as first parameter.

Parameters

ks	The array where to store the sixteen 48 bits round keys. On return ks[0] holds the first round key, ..., ks[15] holds the last round key. Must be allocated prior the call.
val	64 bits key.

des_enc()

uint64_t des_enc	(	uint64_t *	ks,
		uint64_t	val
	)

Enciphers a 64 bits plaintext with a pre-computed key schedule.

Returns

The enciphered plaintext as a 64 bits uint64_t.

Parameters

ks	The pre-computed key schedule.
val	The 64 bits plaintext.

des_dec()

uint64_t des_dec	(	uint64_t *	ks,
		uint64_t	val
	)

Deciphers a 64 bits plaintext with a pre-computed key schedule.

Returns

The deciphered ciphertext as a 64 bits uint64_t.

Parameters

ks	The pre-computed key schedule.
val	The 64 bits ciphertext.

des_check()

int des_check

(

void

)

A functional verification of the DES implementation.

Runs a number of encipherments with des_enc() and the corresponding decipherments with des_dec() and checks the results against pre-computed plaintext, ciphertexts and secret keys. If compiled in DEBUG mode, prints warnings on mismatches or a OK message if the tests pass.

Returns

One on success, zero on errors.

Variable Documentation

left_shifts

uint8_t left_shifts[16]

extern

Number of left shifts per round.

left_shifts[0] corresponds to round #1, ... left_shifts[15] corresponds to round #16. A value of 0 means one shift. A value of 1 means two shifts.