bitmessage-js/lib/address.js

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/**
* Working with Bitmessage addresses.
* @module bitmessage/address
*/
"use strict";
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var assert = require("assert");
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var bufferEqual = require("buffer-equal");
var bs58 = require("bs58");
var varint = require("./varint");
var bmcrypto = require("./crypto");
/**
* Parse Bitmessage Base58 encoded address (with or without `BM-`
* prefix) into address object.
*/
exports.decode = function(str) {
str = str.trim();
if (str.slice(0, 3) === "BM-") {
str = str.slice(3);
}
var bytes;
try {
bytes = bs58.decode(str);
} catch(e) {
return Promise.reject(e);
}
// Checksum validating.
var data = new Buffer(bytes.slice(0, -4));
var checksum = new Buffer(bytes.slice(-4));
return bmcrypto.sha512(data).then(bmcrypto.sha512).then(function(dhash) {
assert(bufferEqual(dhash.slice(0, 4), checksum), "Bad checkum");
var decoded = varint.decode(data);
var version = decoded.value;
assert(version <= 4, "Version too high");
assert(version >= 1, "Version too low");
data = decoded.rest;
decoded = varint.decode(data);
var stream = decoded.value;
var ripe = decoded.rest;
var ripelen = ripe.length;
switch (version) {
case 1:
assert(ripelen === 20);
break;
case 2:
case 3:
assert(ripelen >= 18, "Ripe too short");
assert(ripelen <= 20, "Ripe too long");
break;
case 4:
assert(ripelen >= 4, "Ripe too short");
assert(ripelen <= 20, "Ripe too long");
assert(ripe[0] !== 0, "Ripe encode error");
break;
}
// Prevent extra allocation. God, kill me please for premature
// optimizations.
if (ripelen < 20) {
var zeroes = new Buffer(Array(20 - ripelen));
ripe = Buffer.concat([zeroes, ripe]);
}
return {version: version, stream: stream, ripe: ripe};
});
};