Common functions used in the analysis of TEA. More...

#include "common.hh"
#include "tea.hh"

Functions
void	tea_encrypt (uint32_t v, uint32_t k, int nrounds)

uint32_t	tea_f (uint32_t x, uint32_t k0, uint32_t k1, uint32_t delta, uint32_t lsh_const, uint32_t rsh_const)

uint32_t	tea_f_i (const uint32_t mask_i, const uint32_t k0, const uint32_t k1, const uint32_t delta, const uint32_t lsh_const, const uint32_t rsh_const, const uint32_t x_in)

void	tea_compute_delta_const (uint32_t D[TEA_NCYCLES])

double	tea_add_diff_adjust_to_key (const uint64_t npairs, const int round_idx, const uint32_t da, const uint32_t db, const uint32_t key[4])

double	tea_differential_thres_exper_fk (uint64_t npairs, int r, uint32_t key[4], uint32_t da[2], uint32_t db[2])

uint32_t	tea_add_verify_trail (uint32_t nrounds, uint32_t npairs, uint32_t key[4], differential_t trail[NROUNDS])

uint32_t	tea_add_verify_differential (uint32_t nrounds, uint32_t npairs, uint32_t key[4], differential_t trail[NROUNDS])

void	print_trail_latex (FILE *fp, uint32_t nrounds, uint32_t keys[4], differential_t trail[NROUNDS])

Detailed Description

Common functions used in the analysis of TEA.

Author: V.Velichkov, vesse.nosp@m.lin..nosp@m.velic.nosp@m.hkov.nosp@m.@uni..nosp@m.lu

Function Documentation

void print_trail_latex	(	FILE *	fp,
		uint32_t	nrounds,
		uint32_t	keys[4],
		differential_t	trail[NROUNDS]
	)

Print a differential trail in LaTeX-formatted style, suitable to add in a LaTeX document.

Parameters

fp	FILE pointer for writing; opened and closed by the calling function.
nrounds	number of rounds covered by the trail (NROUNDS).
keys	cryptographic key of TEA.
trail	differential trail for `nrounds`.

double tea_add_diff_adjust_to_key	(	const uint64_t	npairs,
		const int	round_idx,
		const uint32_t	da,
		const uint32_t	db,
		const uint32_t	key[4]
	)

Experimentally adjust the probability of a differential for one round of TEA to a fixed key over a number of chosen plaintexts.

Parameters

npairs	number of chosen plaintext pairs (NPAIRS).
round_idx	index of the round.
da	input difference to the TEA F function.
db	output difference from the TEA F function.
key	cryptographic key of TEA.

uint32_t tea_add_verify_differential	(	uint32_t	nrounds,
		uint32_t	npairs,
		uint32_t	key[4],
		differential_t	trail[NROUNDS]
	)

Given an ADD trail for $N$ rounds of TEA, experimentally verify the probabilities of the corresponding $N$ differentials:

  - Differential for 1 round: round 0. 
  - Differential for 2 rounds: rounds \form#316. 
  - Differential for 3 rounds: rounds \form#317. 
  -  \form#318
  - Differential for \form#315 rounds: rounds \form#319.

Parameters

nrounds	number of rounds covered by the trail (NROUNDS).
npairs	number of chosen plaintext pairs (NPAIRS).
key	cryptographic key of TEA.
trail	differential trail for `nrounds`.

uint32_t tea_add_verify_trail	(	uint32_t	nrounds,
		uint32_t	npairs,
		uint32_t	key[4],
		differential_t	trail[NROUNDS]
	)

Experimentally verify the probability of all 1-round differentials from which an N round ADD trail for TEA is composed.

Parameters

nrounds	number of rounds covered by the trail (NROUNDS).
npairs	number of chosen plaintext pairs (NPAIRS).
key	cryptographic key of TEA.
trail	differential trail for `nrounds`.

void tea_compute_delta_const ( uint32_t D[TEA_NCYCLES] )

Compute all round constants of block cipher TEA.

Parameters

D	all round constants $\delta$ of TEA.

double tea_differential_thres_exper_fk	(	uint64_t	npairs,
		int	r,
		uint32_t	key[4],
		uint32_t	da[2],
		uint32_t	db[2]
	)

Experimentally verify the probability of an r round differential for TEA, for a fixed key, over a number of chosen plaintexts.

Parameters

npairs	number of chosen plaintext pairs (NPAIRS).
r	number of rounds (1 $\le$ `nrounds` $\le$ 64).
da	input state to round `1`.
db	output state after round `r`.
key	cryptographic key of TEA.

void tea_encrypt	(	uint32_t *	v,
		uint32_t *	k,
		int	nrounds
	)

Round-reduced version of block cipher TEA. Reference: https://en.wikipedia.org/wiki/Tiny_Encryption_Algorithm.

Parameters

v	plaintext.
k	secret key.
nrounds	number of rounds (1 $\le$ `nrounds` $\le$ 64).

uint32_t tea_f	(	uint32_t	x,
		uint32_t	k0,
		uint32_t	k1,
		uint32_t	delta,
		uint32_t	lsh_const,
		uint32_t	rsh_const
	)

The F-function of block cipher TEA: $F(x) = ((x \ll 4) + k_0) \oplus (x + \delta) \oplus ((x \gg 5) + k_1)$ .

Parameters

x	input to .
k0	first round key.
k1	second round key.
delta	round constant.
lsh_const	LSH constant (default is 4).
rsh_const	RSH constant (default is 5).

Returns

uint32_t tea_f_i	(	const uint32_t	mask_i,
		const uint32_t	k0,
		const uint32_t	k1,
		const uint32_t	delta,
		const uint32_t	lsh_const,
		const uint32_t	rsh_const,
		const uint32_t	x_in
	)

The F-function of block cipher TEA (tea_f) computed on the first i least-significant (LS) bits.

Parameters

mask_i	`i` bit LSB mask.
k0	first round key.
k1	second round key.
delta	round constant.
lsh_const	LSH constant (default is 4).
rsh_const	RSH constant (default is 5).
x_in	input to .

Returns: $F(x)~ \mathrm{mod}~ 2^i$

Attention: the initial value x_in must be minimum (rsh_const + 1) bits long so that it can be shifted right by rsh_const positions.

See Also: xtea_f()

Functions

Detailed Description

Function Documentation