bitcalc: Offline Calculator for Addresses with Native SegWit (bc1q) & Mnemonic Features

Just a heads up: Use it at your own risk. Always check that the file you download is legit. So, I've been using bitaddress.org for offline BTC cold wallet creation in my beginner classes for ages. But it has two big downsides: First, it only works with P2PKH (the old addresses that start with 1) and doesn't support Native SegWit (the new bech32 addresses that start with bc1q), which are pretty common in modern wallets. Second, it exports raw private keys in WIF format, but it doesn't create BIP-39 mnemonic phrases. After checking out the BIP-361 proposal on quantum migration, I realized that mnemonics might be crucial for proving who owns an address in the future (Phase C aims to use zero-knowledge proofs for recovering funds). Just having the private key won’t cut it anymore. This pushed me to create the generator with the following features. 🔧 Features Two ways to get entropy: You can either use a brain wallet (SHA256ⁿ / password with optional #iterations) OR get secure random numbers (collecting entropy from mouse and keyboard using ArcFour PRNG). Legacy Paths: Supports P2PKH (uncompressed public key) and Native SegWit (compressed public key) with QR code generation included. Mnemonic Path: Follows BIP39 (12/24 words) → PBKDF2 → BIP32 HD → m/84'/0'/0'/0/{0..9}. Mnemonic Recovery: Allows you to restore your seed and generate a list of 10 HD addresses from your mnemonic. Built-in Verification: Check the validity of mnemonics, WIF private keys, and address formats. Bilingual UI: Easily switch between Chinese and English with one click. Fully Offline: Built with grunt into a single HTML file just open it in your browser, no internet needed.