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/*
* ecgen, tool for generating Elliptic curve domain parameters
* Copyright (C) 2017 J08nY
*/
#include "seed.h"
#include "io/output.h"
#include "util/bits.h"
#include "util/memory.h"
seed_t *seed_new(void) { return try_calloc(sizeof(seed_t)); }
seed_t *seed_copy(const seed_t *src, seed_t *dest) {
if (src->seed) {
dest->seed = bits_copy(src->seed);
}
if (src->hash20) {
dest->hash20 = try_memdup(src->hash20, 20);
}
if (src->W) {
dest->W = bits_copy(src->W);
}
return dest;
}
seed_t *seed_new_copy(const seed_t *src) {
seed_t *result = seed_new();
return seed_copy(src, result);
}
seed_t *seed_clone(const seed_t *src, seed_t *dest) {
return seed_copy(src, dest);
}
seed_t *seed_new_clone(const seed_t *src) {
seed_t *result = seed_new();
return seed_clone(src, result);
}
void seed_free(seed_t **seed) {
if (*seed) {
if ((*seed)->seed) {
bits_free(&(*seed)->seed);
}
if ((*seed)->hash20) {
try_free((*seed)->hash20);
}
if ((*seed)->W) {
bits_free(&(*seed)->W);
}
try_free(*seed);
*seed = NULL;
}
}
bool seed_valid(const char *hex_str) {
size_t len = strlen(hex_str);
if (len < 40) {
return false;
}
const char *str_start = hex_str;
if (hex_str[0] == '0' && (hex_str[1] == 'x' || hex_str[1] == 'X')) {
str_start = hex_str + 2;
}
while (*str_start != 0) {
char c = *str_start++;
if (!isxdigit(c)) return false;
}
return true;
}
static bits_t *seed_stoi(const char *cstr) {
const char *seed_str = cstr;
const char *prefix = strstr(cstr, "0x");
if (prefix != NULL) seed_str = prefix + 2;
return bits_from_hex(seed_str);
}
static void seed_hash(seed_t *seed) {
seed->hash20 = try_malloc(20);
bits_sha1(seed->seed, seed->hash20);
}
static void seed_W(seed_t *seed, const config_t *cfg) {
pari_sp ltop = avma;
GEN t = utoi(cfg->bits);
GEN s = floorr(rdivii(subis(t, 1), stoi(160), DEFAULTPREC));
GEN h = subii(t, mulis(s, 160));
bits_t *c0 = bits_from_raw(seed->hash20, 160);
bits_shortenz(c0, 160 - itos(h));
bits_t *W0 = bits_copy(c0);
SET_BIT(W0->bits, 0, 0);
long is = itos(s);
seed->W = bits_copy(W0);
GEN two_g = int2n(seed->seed->bitlen);
for (long i = 1; i <= is; ++i) {
pari_sp btop = avma;
GEN inner = bits_to_i(seed->seed);
inner = addis(inner, i);
inner = modii(inner, two_g);
bits_t *to_hash = bits_from_i(inner);
unsigned char hashout[20];
bits_sha1(to_hash, hashout);
bits_t *Wi = bits_from_raw(hashout, 160);
bits_concatz(seed->W, Wi, NULL);
bits_free(&to_hash);
bits_free(&Wi);
avma = btop;
}
bits_free(&c0);
bits_free(&W0);
avma = ltop;
}
GENERATOR(seed_gen_random) {
seed_t *seed = seed_new();
seed->seed = bits_from_i(random_int(160));
seed_hash(seed);
seed_W(seed, cfg);
curve->seed = seed;
return 1;
}
GENERATOR(seed_gen_argument) {
seed_t *seed = seed_new();
seed->seed = seed_stoi(cfg->seed);
seed_hash(seed);
seed_W(seed, cfg);
curve->seed = seed;
return 1;
}
GENERATOR(seed_gen_input) {
pari_sp ltop = avma;
GEN str = input_string("seed:");
const char *cstr = GSTR(str);
if (!seed_valid(cstr)) {
fprintf(err, "SEED must be at least 160 bits(40 hex characters).\n");
avma = ltop;
return 0;
}
seed_t *seed = seed_new();
seed->seed = seed_stoi(cstr);
seed_hash(seed);
seed_W(seed, cfg);
curve->seed = seed;
return 1;
}
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