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My multiplication loops were not, in fact, off by one.

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This commit is contained in:
Adam Wick
2018-06-04 21:35:13 -07:00
parent 69596c83ec
commit eae2ea49a9
1 changed files with 3 additions and 3 deletions
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6
src/cryptonum/multiplication.rs
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@@ -4,7 +4,7 @@ use cryptonum::{U192, U256, U384, U512, U576,
use std::ops::{Mul,MulAssign}; use std::ops::{Mul,MulAssign};
// This is algorithm 14.12 from "Handbook of Applied Cryptography" // This is algorithm 14.12 from "Handbook of Applied Cryptography"
fn raw_multiplication(x: &[u64], y: &[u64], w: &mut [u64]) pub fn raw_multiplication(x: &[u64], y: &[u64], w: &mut [u64])
{ {
assert_eq!(x.len(), y.len()); assert_eq!(x.len(), y.len());
assert_eq!(x.len() * 2, w.len()); assert_eq!(x.len() * 2, w.len());
@@ -15,9 +15,9 @@ fn raw_multiplication(x: &[u64], y: &[u64], w: &mut [u64])
w[i] = 0; w[i] = 0;
} }
for i in 0..y.len() { // this may legitimately be off by one for i in 0..y.len() {
let mut carry = 0; let mut carry = 0;
for j in 0..x.len() { // ditto for j in 0..x.len() {
let old = w[i+j] as u128; let old = w[i+j] as u128;
let x128 = x[j] as u128; let x128 = x[j] as u128;
let y128 = y[i] as u128; let y128 = y[i] as u128;