Files
cryptonum/src/unsigned/modmul.rs

104 lines
3.5 KiB
Rust

/// Modular multiplication of the type.
pub trait ModMul<T> {
/// Modular multiplication using the given modulus type. If it's possible,
/// we suggest using Barrett values, which are much faster than doing
/// modulo with the number types.
fn modmul(&self, x: &Self, m: &T) -> Self;
}
macro_rules! modmul_impls {
($name: ident, $dbl: ident, $barrett: ident) => {
impl ModMul<$name> for $name {
fn modmul(&self, x: &$name, m: &$name) -> $name {
let mulres = (self as &$name) * x;
let bigm = $dbl::from(m);
let (_, bigres) = mulres.divmod(&bigm);
$name::from(bigres)
}
}
impl ModMul<$barrett> for $name {
fn modmul(&self, x: &$name, m: &$barrett) -> $name {
let mulres = (self as &$name) * x;
m.reduce(&mulres)
}
}
};
}
#[cfg(test)]
macro_rules! generate_modmul_tests {
($name: ident, $lname: ident) => {
#[test]
fn $lname() {
generate_modmul_tests!(body $name, $lname);
}
};
(ignore $name: ident, $lname: ident) => {
#[test]
#[ignore]
fn $lname() {
generate_modmul_tests!(body $name, $lname);
}
};
(body $name: ident, $lname: ident) => {
let fname = build_test_path("modmul", stringify!($name));
run_test(fname.to_string(), 6, |case| {
let (neg0, abytes) = case.get("a").unwrap();
let (neg1, bbytes) = case.get("b").unwrap();
let (neg2, mbytes) = case.get("m").unwrap();
let (neg3, cbytes) = case.get("c").unwrap();
assert!(!neg0 && !neg1 && !neg2 && !neg3);
let a = $name::from_bytes(abytes);
let b = $name::from_bytes(bbytes);
let m = $name::from_bytes(mbytes);
let c = $name::from_bytes(cbytes);
assert_eq!(c, a.modmul(&b, &m));
});
};
}
#[cfg(test)]
macro_rules! generate_barrett_modmul_tests {
($name: ident, $lname: ident, $bname: ident) => {
#[test]
fn $lname() {
generate_barrett_modmul_tests!(body $name, $lname, $bname);
}
};
(ignore $name: ident, $lname: ident, $bname: ident) => {
#[test]
#[ignore]
fn $lname() {
generate_barrett_modmul_tests!(body $name, $lname, $bname);
}
};
(body $name: ident, $lname: ident, $bname: ident) => {
let fname = build_test_path("modmul", stringify!($name));
run_test(fname.to_string(), 6, |case| {
let (neg0, abytes) = case.get("a").unwrap();
let (neg1, bbytes) = case.get("b").unwrap();
let (neg2, mbytes) = case.get("m").unwrap();
let (neg3, cbytes) = case.get("c").unwrap();
let (neg4, kbytes) = case.get("k").unwrap();
let (neg5, ubytes) = case.get("u").unwrap();
assert!(!neg0 && !neg1 && !neg2 && !neg3 && !neg4 && !neg5);
let a = $name::from_bytes(abytes);
let b = $name::from_bytes(bbytes);
let m = $name::from_bytes(mbytes);
let c = $name::from_bytes(cbytes);
let kbig = $name::from_bytes(kbytes);
let k = usize::from(kbig);
let mu = $bname::from_bytes(ubytes);
let bar = $name::new_barrett(k, $bname::from(m), mu);
if k == a.value.len() {
assert_eq!(c, a.modmul(&b, &bar));
}
});
};
}