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rand: extractet some double code into new functions

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this is the first step, in the next one i a going to remove
static mp_digit get_urnd_int_small(int *sign);
static mp_digit get_rnd_int_small(int *sign);
static mp_digit get_urnd_int_big(int *sign);
static mp_digit get_rnd_int_big(int *sign);

RAND: merged a conflict
This commit is contained in:
Malte 2014-04-20 20:08:42 +02:00 committed by malte
parent 60dbab44f5
commit 21022c9ff8
1 changed files with 183 additions and 32 deletions
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215
src/rand.c
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@ -39,17 +39,18 @@
*/ */
static mp_digit get_urnd_int_small(int *sign); static mp_digit get_urnd_int_small(int *sign);
static mp_digit get_rnd_int_small(int *sign); static mp_digit get_rnd_int_small(int *sign);
static mp_digit get_urnd_int_big(int *sign);
static mp_digit get_rnd_int_big(int *sign);
static mp_digit read_int_dev_random();
static mp_digit make_small_int(mp_digit random_int, int* sign);
static mp_digit make_big_int(mp_digit random_int, int* sign);
/** /**
* Gets a random small integer * Reads a single mp_digit out of /dev/random and returns this mp_digit
* from the set {-1, 0, 1} using /dev/random. *
* A zero is signed positiv. * @return the randomly chosen integer
* *sig == 1 means positiv integer.
*
* @param sign stores the signness [out]
* @return random small integer
*/ */
static mp_digit get_rnd_int_small(int *sign) static mp_digit read_int_dev_random()
{ {
int random_data; int random_data;
mp_digit random_int; mp_digit random_int;
@ -66,7 +67,19 @@ static mp_digit get_rnd_int_small(int *sign)
randomDataLen += result; randomDataLen += result;
} }
close(random_data); close(random_data);
return random_int;
}
/**
* Makes a small integer from the set {-1, 0, 1}
* out of a randomly chosen integer.
*
* @param random_int a randomly chosen mp_digit
* @param sign a integer to store the sign (1==positiv)
* @return random small integer from the set {-1, 0, 1}
*/
static mp_digit make_small_int(mp_digit random_int, int* sign)
{
random_int = random_int % 3; random_int = random_int % 3;
if (random_int == 1) { if (random_int == 1) {
@ -77,6 +90,23 @@ static mp_digit get_rnd_int_small(int *sign)
} else { } else {
*sign = 0; *sign = 0;
} }
return random_int;
}
/**
* Gets a random small integer
* from the set {-1, 0, 1} using /dev/random.
* A zero is signed positiv.
* *sig == 1 means positiv integer.
*
* @param sign stores the signness [out]
* @return random small integer
*/
static mp_digit get_rnd_int_small(int *sign)
{
mp_digit random_int = read_int_dev_random();
random_int = make_small_int(random_int, sign);
return random_int; return random_int;
} }
@ -84,7 +114,6 @@ static mp_digit get_rnd_int_small(int *sign)
* Gets a random polynomial with coefficients * Gets a random polynomial with coefficients
* from the set {-1 ,0 ,1} using /dev/random. * from the set {-1 ,0 ,1} using /dev/random.
* *
*
* @param ctx the NTRU context * @param ctx the NTRU context
* @return newly allocated polynomial, must be freed with delete_polynom() * @return newly allocated polynomial, must be freed with delete_polynom()
*/ */
@ -106,11 +135,29 @@ pb_poly *ntru_get_rnd_poly_small(ntru_context *ctx)
poly->terms[i].sign = 1; poly->terms[i].sign = 1;
} }
poly->used = ctx->N; poly->used = ctx->N;
//pb_clamp(poly); pb_clamp(poly);
return poly; return poly;
} }
/**
* Reads a single mp_digit out of /dev/urandom and returns this mp_digit
*
* @return the randomly chosen integer
*/
static mp_digit read_int_dev_urandom()
{
int random_data;
mp_digit random_int;
ssize_t result;
random_data = open("/dev/urandom", O_RDONLY);
if ((result = read(random_data, &random_int, sizeof(random_int))) < 0)
NTRU_ABORT("Unable to read /dev/urandom.\n");
close(random_data);
return random_int;
}
/** /**
* Gets a random small integer * Gets a random small integer
* from the set {-1, 0, 1} using /dev/urandom. * from the set {-1, 0, 1} using /dev/urandom.
@ -122,27 +169,8 @@ pb_poly *ntru_get_rnd_poly_small(ntru_context *ctx)
*/ */
static mp_digit get_urnd_int_small(int *sign) static mp_digit get_urnd_int_small(int *sign)
{ {
int random_data; mp_digit random_int = read_int_dev_urandom();
mp_digit random_int; random_int = make_small_int(random_int, sign);
ssize_t result;
random_data = open("/dev/urandom", O_RDONLY);
if ((result = read(random_data, &random_int, sizeof(random_int))) < 0)
NTRU_ABORT("Unable to read /dev/urandom.\n");
close(random_data);
random_int = random_int % 3;
if (random_int == 1) {
*sign = 0;
} else if (random_int == 2) {
random_int = 1;
*sign = 1;
} else {
random_int = 1;
*sign = 0;
}
return random_int; return random_int;
} }
@ -163,7 +191,7 @@ pb_poly *ntru_get_urnd_poly_small(ntru_context *ctx)
for (unsigned int i = 0; i < ctx->N; i++) { for (unsigned int i = 0; i < ctx->N; i++) {
int sign; int sign;
unsigned long c = get_urnd_int_small(&sign); int c = get_urnd_int_small(&sign);
mp_set(&(poly->terms[i]), (mp_digit) c); mp_set(&(poly->terms[i]), (mp_digit) c);
@ -176,3 +204,126 @@ pb_poly *ntru_get_urnd_poly_small(ntru_context *ctx)
return poly; return poly;
} }
/**
* Makes a big integer from the borders of BIG_RAND_MAX
* and BIG_RAND_MIN out of a randomly chosen integer.
*
* @param random_int a randomly chosen mp_digit
* @param sign a integer to store the sign (1==positiv)
* @return random small integer from the set {-1, 0, 1}
*/
static mp_digit make_big_int(mp_digit random_int, int* sign)
{
random_int = random_int % abs(BIG_RAND_MAX - BIG_RAND_MIN);
if (random_int < BIG_RAND_MAX) {
*sign = 1;
} else if (random_int > BIG_RAND_MAX) {
*sign = 0;
random_int -= BIG_RAND_MAX;
} else if (random_int == BIG_RAND_MAX) {
random_int = abs(BIG_RAND_MIN);
*sign = 0;
} else {
NTRU_ABORT("Error while parsing big random Integer.\n");
}
return random_int;
}
/**
* Gets a random big integer
* from the borders of BIG_RAND_MAX and
* BIG_RAND_MIN using /dev/random.
* A zero is signed positiv.
* *sig == 1 means positiv integer.
*
* @param sign stores the signness [out]
* @return random small integer
*/
static mp_digit get_rnd_int_big(int *sign)
{
mp_digit random_int = read_int_dev_random();
random_int = make_big_int(random_int, sign);
return random_int;
}
/**
* Gets a random polynomial with coefficients
* from the borders of BIG_RAND_MAX and
* BIG_RAND_MIN using /dev/random.
*
* @param ctx the NTRU context
* @return newly allocated polynomial, must be freed with delete_polynom()
*/
pb_poly *ntru_get_rnd_poly_big(ntru_context *ctx)
{
mp_int chara;
init_integer(&chara);
pb_poly *poly = malloc(sizeof(pb_poly));
init_polynom_size(poly, &chara, ctx->N);
mp_clear(&chara);
for (unsigned int i = 0; i < ctx->N; i++) {
int sign;
int c = get_rnd_int_big(&sign);
mp_set(&(poly->terms[i]), (mp_digit) c);
if (sign == 1)
poly->terms[i].sign = 1;
}
poly->used = ctx->N;
pb_clamp(poly);
return poly;
}
/**
* Gets a random big integer
* from the borders of BIG_RAND_MAX and
* BIG_RAND_MIN using /dev/urandom.
* A zero is signed positiv.
* *sig == 1 means positiv integer.
*
* @param sign stores the signness [out]
* @return random small integer
*/
static mp_digit get_urnd_int_big(int *sign)
{
mp_digit random_int = read_int_dev_urandom();
random_int = random_int % abs(BIG_RAND_MAX - BIG_RAND_MIN);
random_int = make_big_int(random_int, sign);
return random_int;
}
/**
* Gets a random polynomial with coefficients
* from the borders of BIG_RAND_MAX and
* BIG_RAND_MIN using /dev/urandom.
*
* @param ctx the NTRU context
* @return newly allocated polynomial, must be freed with delete_polynom()
*/
pb_poly *ntru_get_urnd_poly_big(ntru_context *ctx)
{
mp_int chara;
init_integer(&chara);
pb_poly *poly = malloc(sizeof(pb_poly));
init_polynom_size(poly, &chara, ctx->N);
mp_clear(&chara);
for (unsigned int i = 0; i < ctx->N; i++) {
int sign;
int c = get_urnd_int_big(&sign);
mp_set(&(poly->terms[i]), (mp_digit) c);
if (sign == 1)
poly->terms[i].sign = 1;
}
poly->used = ctx->N;
pb_clamp(poly);
return poly;
}