int cp_ecss_ver(bn_t e, bn_t s, uint8_t *msg, int len, ec_t q) {
bn_t n, ev, rv;
ec_t p;
uint8_t hash[MD_LEN];
uint8_t m[len + FC_BYTES];
int result = 0;
bn_null(n);
bn_null(ev);
bn_null(rv);
ec_null(p);
TRY {
bn_new(n);
bn_new(ev);
bn_new(rv);
ec_new(p);
ec_curve_get_ord(n);
if (bn_sign(e) == BN_POS && bn_sign(s) == BN_POS && !bn_is_zero(s)) {
if (bn_cmp(e, n) == CMP_LT && bn_cmp(s, n) == CMP_LT) {
ec_mul_sim_gen(p, s, q, e);
ec_get_x(rv, p);
bn_mod(rv, rv, n);
memcpy(m, msg, len);
bn_write_bin(m + len, FC_BYTES, rv);
md_map(hash, m, len + FC_BYTES);
if (8 * MD_LEN > bn_bits(n)) {
len = CEIL(bn_bits(n), 8);
bn_read_bin(ev, hash, len);
bn_rsh(ev, ev, 8 * MD_LEN - bn_bits(n));
} else {
bn_read_bin(ev, hash, MD_LEN);
}
bn_mod(ev, ev, n);
result = dv_cmp_const(ev->dp, e->dp, MIN(ev->used, e->used));
result = (result == CMP_NE ? 0 : 1);
if (ev->used != e->used) {
result = 0;
}
}
}
}
CATCH_ANY {
THROW(ERR_CAUGHT);
}
FINALLY {
bn_free(n);
bn_free(ev);
bn_free(rv);
ec_free(p);
}
return result;
}
int fp_cmp(const fp_t a, const fp_t b) {
return dv_cmp_const(a, b, RLC_FP_DIGS);
}