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include!(concat!(env!("OUT_DIR"), "/constants.rs"));
use classgroup::BigNumExt;
use num_traits::Zero;
use sha2::{digest::FixedOutput, Digest, Sha256};
use std::u16;
fn random_bytes_from_seed(seed: &[u8], byte_count: usize) -> Vec<u8> {
assert!(byte_count <= 32 * ((1 << 16) - 1));
let mut blob = Vec::with_capacity(byte_count);
let mut extra: u16 = 0;
while blob.len() < byte_count {
let mut hasher = Sha256::new();
hasher.input(seed);
let extra_bits: [u8; 2] = [((extra & 0xFF00) >> 8) as _, (extra & 0xFF) as _];
hasher.input(&extra_bits);
blob.extend_from_slice(&hasher.fixed_result()[..]);
extra += 1;
}
blob.resize(byte_count, 0);
blob
}
pub fn create_discriminant<T: BigNumExt>(seed: &[u8], length: u16) -> T {
let (mut n, residue) = {
let extra: u8 = (length as u8) & 7;
let random_bytes_len = ((usize::from(length) + 7) >> 3) + 2;
let random_bytes = random_bytes_from_seed(seed, random_bytes_len);
let (n, last_2) = random_bytes.split_at(random_bytes_len - 2);
let numerator = (usize::from(last_2[0]) << 8) + usize::from(last_2[1]);
let n = T::from(n) >> usize::from((8 - extra) & 7);
(n, RESIDUES[numerator % RESIDUES.len()])
};
n.setbit(usize::from(length - 1));
debug_assert!(n >= Zero::zero());
let rem = n.frem_u32(M);
if residue > rem {
n = n + u64::from(residue - rem);
} else {
n = n - u64::from(rem - residue);
}
debug_assert!(n >= Zero::zero());
loop {
let mut sieve = vec![false; 1 << 16];
for &(p, q) in SIEVE_INFO.iter() {
let mut i: usize = (n.crem_u16(p) as usize * q as usize) % p as usize;
while i < sieve.len() {
sieve[i] = true;
i += p as usize;
}
}
for (i, &x) in sieve.iter().enumerate() {
let i = i as u32;
if !x {
let q = u64::from(M) * u64::from(i);
n = n + q;
if n.probab_prime(2) {
return -n;
}
n = n - q;
}
}
n = n + (u64::from(M) * (1 << 16)) as u64
}
}
#[cfg(test)]
mod test {
use super::*;
use classgroup::{gmp_classgroup::GmpClassGroup, ClassGroup};
type Mpz = <GmpClassGroup as ClassGroup>::BigNum;
use std::str::FromStr;
#[test]
fn check_discriminant_1() {
assert_eq!(
create_discriminant::<Mpz>(b"\xaa", 40),
(-685_537_176_559i64).into()
);
}
#[test]
fn check_discriminant_3() {
assert_eq!(
create_discriminant::<Mpz>(b"\xaa", 1024),
Mpz::from_str(
"-112084717443890964296630631725167420667316836131914185144761\
7438378168250988242739496385274308134767869324152361453294226\
8295868231081182819214054220080323345750407342623884342617809\
8794592117225058677336074005099949757067786815439982423354682\
0386024058617141397148586038290164093146862666602485017735298\
03183"
)
.unwrap()
)
}
#[test]
fn check_discriminant_2() {
assert_eq!(
create_discriminant::<Mpz>(b"\xaa", 2048),
-Mpz::from_str(
"201493927071865251625903550712920535753645598483515670853547009\
878440933309489362800393797428711071833308081461824159206915864\
150805748296170245037221957772328044276705571745811271212292422\
075849739248257870371300001313586036515879618764093772248760562\
386804073478433157526816295216137723803793411828867470089409596\
238958950007370719325959579892866588928887249912429688364409867\
895510817680171869190054122881274299350947669820596157115994418\
034091728887584373727555384075665624624856766441009974642693066\
751400054217209981490667208950669417773785631693879782993019167\
69407006303085854796535778826115224633447713584423"
)
.unwrap()
);
}
#[test]
fn check_random_bytes() {
assert_eq!(
&random_bytes_from_seed(b"\xaa", 7),
b"\x9f\x9d*\xe5\xe7<\xcb"
);
assert_eq!(
&random_bytes_from_seed(b"\xaa", 258)[..],
&b"\x9f\x9d*\xe5\xe7<\xcbq\xa4q\x8e\
\xbc\xf0\xe3:\xa2\x98\xf8\xbd\xdc\xaa\xcbi\xcb\x10\xff\x0e\xafv\xdb\xec!\xc4K\
\xc6Jf\xf3\xa5\xda.7\xb7\xef\x87I\x85\xb8YX\xfc\xf2\x03\xa1\x8f4\xaf`\xab\xae]n\
\xcc,g1\x12EI\xc7\xd5\xe2\xfc\x8b\x9a\xde\xd5\xf3\x8f'\xcd\x08\x0fU\xc7\xee\xa85\
[>\x87]\x07\x82\x00\x13\xce\xf7\xc3/@\xef\x08v\x8f\x85\x87dm(1\x8b\xd9w\xffA]xzY\
\xa0,\xebz\xff\x03$`\x91\xb66\x88-_\xa9\xf1\xc5\x8e,\x15\xae\x8f\x04\rvhnU3f\x84\
[{$\xa6l\x95w\xa9\x1f\xba\xa8)\x05\xe6\x8f\x167o\x11/X\x9cl\xab\x9c\xcb}\xec\x88\
\xf8\xa5\xabXpY\xb0\x88\xed@r\x05\xba\\\x03\xf6\x91\xf8\x03\xca\x18\x1c\xcdH\x1c\
\x91\xe1V\xed;\x94oJ\xa8 \xa4\x97\xb7K\xce\xc4e\xea\xa2\xbf\x8b\x1f\x90\x87\xc8\
\x15\xee\x0e\x0fPC:\xb5\xe1g\x97\xea/_\x86c\xaf\x12Wp\xfd\x11\xdb\x17\xe6\x9f\
\xa5\x8a"[..]
);
}
}