Adam Wick
fa872c951a
Previously, we used a little bit of generation to drive a lot of Rust macros. This works, but it's a little confusing to read and write. In addition, we used a lot of implementations with variable timings based on their input, which isn't great for crypto. This is the start of an attempt to just generate all of the relevant Rust code directly, and to use timing-channel resistant implementations for most of the routines.
93 lines
2.5 KiB
Rust
93 lines
2.5 KiB
Rust
pub fn scale(dest: &mut [u64], bignum: &[u64], factor: u64)
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{
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let len = bignum.len();
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let factor128 = factor as u128;
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let mut carry = 0;
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assert_eq!(dest.len(), len+1, "Bad destination size in scale");
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for i in 0..len {
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let digit128 = bignum[i] as u128;
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let res128 = carry + (digit128 * factor128);
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dest[i] = res128 as u64;
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carry = res128 >> 64;
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}
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dest[len] = carry as u64;
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}
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macro_rules! scale_impls
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{
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($base: ident, $big: ident) => {
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scale_impls!($base, $big, u8);
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scale_impls!($base, $big, u16);
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scale_impls!($base, $big, u32);
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scale_impls!($base, $big, u64);
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scale_impls!($base, $big, usize);
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};
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($base: ident, $big: ident, $prim: ident) => {
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impl Mul<$prim> for $base {
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type Output = $big;
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fn mul(self, factor: $prim) -> $big {
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&self * factor
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}
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}
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impl<'a> Mul<$prim> for &'a $base {
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type Output = $big;
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fn mul(self, factor: $prim) -> $big {
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let mut res = $big::zero();
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scale(&mut res.value, &self.value, factor as u64);
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res
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}
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}
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impl Mul<$base> for $prim {
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type Output = $big;
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fn mul(self, rhs: $base) -> $big {
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rhs.mul(self)
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}
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}
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impl<'a> Mul<&'a $base> for $prim {
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type Output = $big;
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fn mul(self, rhs: &$base) -> $big {
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rhs.mul(self)
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}
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}
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}
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}
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#[cfg(test)]
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macro_rules! generate_scale_tests
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{
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($name: ident, $lname: ident, $big: ident) => {
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#[test]
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fn $lname() {
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generate_scale_tests!(body $name, $lname, $big);
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}
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};
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(ignore $name: ident, $lname: ident, $big: ident) => {
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#[test]
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#[ignore]
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fn $lname() {
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generate_scale_tests!(body $name, $lname, $big);
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}
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};
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(body $name: ident, $lname: ident, $big: ident) => {
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let fname = build_test_path("scale", stringify!($name));
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run_test(fname.to_string(), 3, |case| {
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let (neg0, abytes) = case.get("a").unwrap();
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let (neg1, bbytes) = case.get("b").unwrap();
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let (neg2, cbytes) = case.get("c").unwrap();
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assert!(!neg0 && !neg1 && !neg2);
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let a = $name::from_bytes(abytes);
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let b = $name::from_bytes(bbytes);
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let c = $big::from_bytes(cbytes);
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assert_eq!(c, &a * b.value[0]);
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});
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};
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} |