homebridge-sense-energy-monitor/dist/totp.js

Enhanced Homebridge plugin for Sense Home Energy Monitor with comprehensive API integration and real-time monitoring

import { createHmac } from 'node:crypto';
const BASE32_CHARS = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567';
export function base32Decode(encoded) {
    let bits = '';
    for (const char of encoded) {
        const val = BASE32_CHARS.indexOf(char);
        if (val === -1) {
            continue;
        }
        bits += val.toString(2).padStart(5, '0');
    }
    const bytes = [];
    for (let i = 0; i + 8 <= bits.length; i += 8) {
        bytes.push(parseInt(bits.substring(i, i + 8), 2));
    }
    return Buffer.from(bytes);
}
// RFC 6238 TOTP: HMAC-SHA1, 30-second window, 6 digits.
// `now` is injectable for testing.
export function generateTotp(secret, now = Date.now()) {
    const normalized = secret.replace(/\s/g, '').toUpperCase();
    const key = base32Decode(normalized);
    if (key.length === 0) {
        throw new Error('Invalid TOTP secret: base32 decoding produced no data');
    }
    const timeCounter = Math.floor(now / 1000 / 30);
    const counterBuffer = Buffer.alloc(8);
    counterBuffer.writeUInt32BE(Math.floor(timeCounter / 0x100000000), 0);
    counterBuffer.writeUInt32BE(timeCounter % 0x100000000, 4);
    const hash = createHmac('sha1', key).update(counterBuffer).digest();
    const offset = hash[hash.length - 1] & 0xf;
    const binary = ((hash[offset] & 0x7f) << 24) |
        ((hash[offset + 1] & 0xff) << 16) |
        ((hash[offset + 2] & 0xff) << 8) |
        (hash[offset + 3] & 0xff);
    return (binary % 1000000).toString().padStart(6, '0');
}
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