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descriptors.js
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descriptors.js
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"use strict";
// original file: test/functional/test_framework/descriptors.py at 2d83a20113c109f3325316c42540b3f23ce18bc7
// only contains descsum_create and dependencies
// Copyright (c) 2019 Pieter Wuille
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
Object.defineProperty(exports, "__esModule", { value: true });
exports.descsumCreate = void 0;
// Utility functions related to output descriptors
const INPUT_CHARSET = '0123456789()[],\'/*abcdefgh@:$%{}IJKLMNOPQRSTUVWXYZ&+-.;<=>?!^_|~ijklmnopqrstuvwxyzABCDEFGH`#"\\ ';
const CHECKSUM_CHARSET = 'qpzry9x8gf2tvdw0s3jn54khce6mua7l';
const GENERATOR = [0xf5dee51989n, 0xa9fdca3312n, 0x1bab10e32dn, 0x3706b1677an, 0x644d626ffdn];
/** Internal function that computes the descriptor checksum. */
function descsumPolymod(symbols) {
let chk = 1n;
for (const value of symbols) {
const top = chk >> 35n;
chk = ((chk & 0x7ffffffffn) << 5n) ^ BigInt(value);
for (let i = 0; i < 5; i++) {
chk ^= (top >> BigInt(i)) & 1n ? GENERATOR[i] : 0n;
}
}
return chk;
}
/** Internal function that does the character to symbol expansion */
function descsumExpand(s) {
let groups = [];
const symbols = [];
for (const c of s.split('')) {
if (!INPUT_CHARSET.includes(c)) {
return;
}
const v = INPUT_CHARSET.indexOf(c);
symbols.push(v & 31);
groups.push(v >> 5);
if (groups.length === 3) {
symbols.push(groups[0] * 9 + groups[1] * 3 + groups[2]);
groups = [];
}
}
if (groups.length === 1) {
symbols.push(groups[0]);
}
else if (groups.length === 2) {
symbols.push(groups[0] * 3 + groups[1]);
}
return symbols;
}
/** Add a checksum to a descriptor without */
function descsumCreate(s) {
const symbols = descsumExpand(s).concat(0, 0, 0, 0, 0, 0, 0, 0);
const checksum = descsumPolymod(symbols) ^ 1n;
let c = s + '#';
for (let i = 0n; i < 8n; i++) {
c += CHECKSUM_CHARSET[Number((checksum >> (5n * (7n - i))) & 31n)];
}
return c;
}
exports.descsumCreate = descsumCreate;