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secp256k1: es6ify length normalization.

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Christopher Jeffrey 2017-08-13 12:21:44 -07:00
parent e1e71a6e81
commit ebb79e5ff1
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GPG Key ID: 8962AB9DE6666BBD
1 changed files with 23 additions and 21 deletions
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44
lib/crypto/secp256k1-browser.js
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@ -297,48 +297,50 @@ ec.isLowS = function isLowS(raw) {
function normalizeLength(sig) { function normalizeLength(sig) {
let data = sig; let data = sig;
const p = { place: 0 }; let pos = 0;
let len;
if (data[p.place++] !== 0x30) if (data[pos++] !== 0x30)
return sig; return sig;
const len = getLength(data, p); [len, pos] = getLength(data, pos);
if (data.length > len + p.place) if (data.length > len + pos)
data = data.slice(0, len + p.place); data = data.slice(0, len + pos);
if (data[p.place++] !== 0x02) if (data[pos++] !== 0x02)
return sig; return sig;
const rlen = getLength(data, p); // R length.
p.place += rlen; [len, pos] = getLength(data, pos);
if (data[p.place++] !== 0x02) pos += len;
if (data[pos++] !== 0x02)
return sig; return sig;
const slen = getLength(data, p); // S length.
if (data.length > slen + p.place) [len, pos] = getLength(data, pos);
data = data.slice(0, slen + p.place);
if (data.length > len + pos)
data = data.slice(0, len + pos);
return data; return data;
} }
function getLength(buf, p) { function getLength(buf, pos) {
const initial = buf[p.place++]; const initial = buf[pos++];
if (!(initial & 0x80)) if (!(initial & 0x80))
return initial; return [initial, pos];
const len = initial & 0xf; const len = initial & 0xf;
let off = p.place;
let val = 0; let val = 0;
for (let i = 0; i < len; i++, off++) { for (let i = 0; i < len; i++) {
val <<= 8; val <<= 8;
val |= buf[off]; val |= buf[pos++];
} }
p.place = off; return [val, pos];
return val;
} }