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index.js
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index.js
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const BN = require('bn.js');
const elliptic = require('elliptic');
const keccak = require('keccak');
const Buffer = require('safe-buffer').Buffer;
const ed25519 = require('elliptic').eddsa('ed25519');
const cnBase58 = (function () {
var b58 = {};
var alphabet_str = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
var alphabet = [];
for (var i = 0; i < alphabet_str.length; i++) {
alphabet.push(alphabet_str.charCodeAt(i));
}
var encoded_block_sizes = [0, 2, 3, 5, 6, 7, 9, 10, 11];
var alphabet_size = alphabet.length;
var full_block_size = 8;
var full_encoded_block_size = 11;
function hextobin(hex) {
if (hex.length % 2 !== 0) throw "Hex string has invalid length!";
var res = new Uint8Array(hex.length / 2);
for (var i = 0; i < hex.length / 2; ++i) {
res[i] = parseInt(hex.slice(i * 2, i * 2 + 2), 16);
}
return res;
}
function bintostr(bin) {
var out = [];
for (var i = 0; i < bin.length; i++) {
out.push(String.fromCharCode(bin[i]));
}
return out.join("");
}
function uint8_be_to_64(data) {
if (data.length < 1 || data.length > 8) {
throw "Invalid input length";
}
var res = new BN(0);
var twopow8 = new BN(2).pow(new BN(8));
var i = 0;
switch (9 - data.length) {
case 1:
res = res.add(new BN(data[i++]));
case 2:
res = res.mul(twopow8).add(new BN(data[i++]));
case 3:
res = res.mul(twopow8).add(new BN(data[i++]));
case 4:
res = res.mul(twopow8).add(new BN(data[i++]));
case 5:
res = res.mul(twopow8).add(new BN(data[i++]));
case 6:
res = res.mul(twopow8).add(new BN(data[i++]));
case 7:
res = res.mul(twopow8).add(new BN(data[i++]));
case 8:
res = res.mul(twopow8).add(new BN(data[i++]));
break;
default:
throw "Impossible condition";
}
return res;
}
b58.encode_block = function (data, buf, index) {
if (data.length < 1 || data.length > full_encoded_block_size) {
throw "Invalid block length: " + data.length;
}
var num = uint8_be_to_64(data);
var i = encoded_block_sizes[data.length] - 1;
while (num.cmp(new BN(0)) === 1) {
var remainder = num.mod(new BN(alphabet_size));
num = num.div(new BN(alphabet_size));
buf[index + i] = alphabet[remainder.toNumber()];
i--;
}
return buf;
};
b58.encode = function (hex) {
var data = hextobin(hex);
if (data.length === 0) {
return "";
}
var full_block_count = Math.floor(data.length / full_block_size);
var last_block_size = data.length % full_block_size;
var res_size = full_block_count * full_encoded_block_size + encoded_block_sizes[last_block_size];
var res = new Uint8Array(res_size);
var i;
for (i = 0; i < res_size; ++i) {
res[i] = alphabet[0];
}
for (i = 0; i < full_block_count; i++) {
res = b58.encode_block(data.subarray(i * full_block_size, i * full_block_size + full_block_size), res, i * full_encoded_block_size);
}
if (last_block_size > 0) {
res = b58.encode_block(data.subarray(full_block_count * full_block_size, full_block_count * full_block_size + last_block_size), res, full_block_count * full_encoded_block_size)
}
return bintostr(res);
};
return b58;
})();
function fastHash(hex) {
return keccak('keccak256').update(Buffer.from(hex, 'hex')).digest('hex');
}
const l = new BN(2).pow(new BN(252)).add(new BN("27742317777372353535851937790883648493", 10));
function hashToScalar(hex) {
let h = fastHash(hex);
let s = elliptic.utils.intFromLE(h);
s = s.umod(l);
return s;
}
function pointToHex(p) {
return elliptic.utils.toHex(ed25519.encodePoint(p, 'hex'));
}
function intToLittleEndianUint32Hex(value) {
let h = value.toString(16);
if(h.length>8) throw 'value must not equal or exceed 2^32';
while(h.length<8) h = '0' + h;
return h.match(/../g).reverse().join('');
}
function asciiToHex(str) {
var a = [];
for (var n = 0, l = str.length; n < l; n ++) {
var hex = Number(str.charCodeAt(n)).toString(16);
if(hex.length==1) hex = '0' + hex;
a.push(hex);
}
return a.join('');
}
const PUBLIC_ADDRESS_PREFIX_HEX = '12';
const PUBLIC_SUBADDRESS_PREFIX_HEX = '2a';
const SUBADDR_HEX = asciiToHex('SubAddr') + '00';
function getSubaddressPublicSpendKeyPoint(privateViewKeyBytes, publicSpendKeyBytes, accountIndex, subaddressIndex) {
let data = SUBADDR_HEX + privateViewKeyBytes + intToLittleEndianUint32Hex(accountIndex) + intToLittleEndianUint32Hex(subaddressIndex);
let m = hashToScalar(data);
let M = ed25519.curve.g.mul(m);
let B = ed25519.decodePoint(publicSpendKeyBytes);
let D = B.add(M);
return D;
}
function getSubaddress(privateViewKeyHex, publicSpendKeyHex, accountIndex, subaddressIndex) {
let addressPrefix;
let C, D;
if(accountIndex==0 && subaddressIndex==0) {
addressPrefix = PUBLIC_ADDRESS_PREFIX_HEX;
D = ed25519.decodePoint(publicSpendKeyHex);
C = ed25519.curve.g.mul(elliptic.utils.intFromLE(privateViewKeyHex));
}
else {
addressPrefix = PUBLIC_SUBADDRESS_PREFIX_HEX;
D = getSubaddressPublicSpendKeyPoint(privateViewKeyHex, publicSpendKeyHex, accountIndex, subaddressIndex);
C = D.mul(elliptic.utils.intFromLE(privateViewKeyHex));
}
let hex = addressPrefix + pointToHex(D) + pointToHex(C);
let checksumHex = fastHash(hex).substring(0, 8);
hex += checksumHex;
return cnBase58.encode(hex);
}
module.exports = {getSubaddress: getSubaddress};