@ordinalsbot/bitcoin-fee-estimator/dist/utils/bs58.js

A library for calculating Bitcoin transaction fees

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.bs58Decode = bs58Decode;
const crypto_1 = require("crypto");
const BASE58_ALPHABET = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
function bs58Decode(input) {
    const result = [];
    let leadingZeros = 0;
    for (let i = 0; i < input.length && input[i] === "1"; i++) {
        leadingZeros++;
    }
    let value = BigInt(0);
    for (let i = leadingZeros; i < input.length; i++) {
        const c = input[i];
        const index = BASE58_ALPHABET.indexOf(c);
        if (index === -1)
            throw new Error("Invalid Base58 character");
        value = value * BigInt(58) + BigInt(index);
    }
    while (value > 0) {
        result.unshift(Number(value % BigInt(256)));
        value = value / BigInt(256);
    }
    for (let i = 0; i < leadingZeros; i++) {
        result.unshift(0);
    }
    if (result.length < 4)
        throw new Error("Invalid checksum");
    const payload = result.slice(0, -4);
    const checksum = result.slice(-4);
    const hash1 = (0, crypto_1.createHash)("sha256").update(Buffer.from(payload)).digest();
    const hash2 = (0, crypto_1.createHash)("sha256").update(hash1).digest();
    const expectedChecksum = hash2.subarray(0, 4);
    if (!Buffer.from(checksum).equals(expectedChecksum)) {
        throw new Error("Invalid checksum");
    }
    return payload;
}