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poly1305: minor.

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This commit is contained in:
Christopher Jeffrey 2017-07-09 16:27:02 -07:00
parent 18c1476de9
commit f2a939de70
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GPG Key ID: 8962AB9DE6666BBD
1 changed files with 14 additions and 3 deletions
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17
lib/crypto/poly1305.js
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@ -104,10 +104,13 @@ Poly1305.prototype.blocks = function blocks(data, bytes, m) {
// h *= r, (partial) h %= p
for (let i = 0; i < 10; i++) {
d[i] = c;
for (let j = 0; j < 10; j++) {
d[i] += this.h[j] * (j <= i
? this.r[i - j]
: 5 * this.r[i + 10 - j]);
if (j <= i)
d[i] += this.r[i - j];
else
d[i] += 5 * this.r[i + 10 - j]);
// Sum(h[i] * r[i] * 5) will overflow slightly
// above 6 products with an unclamped r, so
// carry at 5
@ -116,9 +119,11 @@ Poly1305.prototype.blocks = function blocks(data, bytes, m) {
d[i] &= 0x1fff;
}
}
c += d[i] >>> 13;
d[i] &= 0x1fff;
}
c = (c << 2) + c; // c *= 5
c += d[0];
d[0] = (c & 0x1fff);
@ -146,15 +151,21 @@ Poly1305.prototype.update = function update(data) {
// handle leftover
if (this.leftover) {
let want = 16 - this.leftover;
if (want > bytes)
want = bytes;
for (let i = 0; i < want; i++)
this.buffer[this.leftover + i] = data[m + i];
bytes -= want;
m += want;
this.leftover += want;
if (this.leftover < 16)
return;
this.blocks(this.buffer, 16, 0);
this.leftover = 0;
}