JavaScript version

Philips Sonicare NFC Password generation

function crc16(crc, buffer) {
    for (let byte of buffer) {
        crc ^= BigInt(byte) << BigInt(8);
        for (let i = 0; i < 8; i++) {
            if (crc & BigInt(0x8000)) {
                crc = (crc << BigInt(1)) ^ BigInt(0x1021);
            } else {
                crc <<= BigInt(1);
            }
            crc &= BigInt(0xFFFF);
        }
    }
    return crc;
}

function generatePassword(uid, mfg) {
    let crc = crc16(BigInt(0x49A3), uid); // Calculate the UID CRC
    crc = crc | crc16(crc, mfg) << BigInt(16); // Calculate the MFG CRC
    crc = ((crc >> BigInt(8)) & BigInt(0x00FF00FF)) | ((crc << BigInt(8)) & BigInt(0xFF00FF00)); // Rotate the bytes

    let password = crc.toString(16).toUpperCase().replace(/(..)(..)(..)(..)/g, '$1:$2:$3:$4'); // Format the password
    return password;
}