Encode algorithm QR-code
try this tutorial http://www.thonky.com/qr-code-tutorial/, very good in-depth tutorial on creating QR-codes, but only for a certain type of QR-code.
qr-code
Aztec barcode vs QR-Code
Although Aztec Codes are more compact and tunable, there is poor support for them among open, non-proprietary software. I would still use QR Codes for now, which have very mature software support on a wide variety of platforms. If space is at a premium for you, and you do not care for users to be … Read more
What is the spec for formatting data in QR codes? I can not find it anywhere
There is no official specification for this — the QR code spec does not say anything about the contents. Everything I know about the commonly-used and de facto formats and conventions is summarized in this wiki: https://github.com/zxing/zxing/wiki/Barcode-Contents
How to generate a QR Code for Google Authenticator that correctly shows Issuer displayed above the OTP?
The responses recommending usage of Google Charts are absolutely terrible from information security point of view. That’s essentially sharing the TOTP secret as well as your username (alice@google.com) and issuer (Example) with a third-party company with no legal obligation to keep them secret, and doing that over a GET request! Doing so you violate not … Read more
Mechanism behind QR code scanning of WhatsApp web/desktop app
It works like this : 1- You open the following URL on your browser : https://web.whatsapp.com/ 2- The Browser loads the page with all sorts of JS and CSS stuff , but also opens a WebSocket ( wss://w4.web.whatsapp.com/ws ) – Check this image : 2.1- Every 20000 milliseconds you see traffic on the WebSocket for … Read more
QR CODE max char length
A summary of the specification is here: * http://en.wikipedia.org/wiki/QR_code Numeric only Max. 7,089 characters (0, 1, 2, 3, 4, 5, 6, 7, 8, 9) Alphanumeric Max. 4,296 characters (0–9, A–Z [upper-case only], space, $, %, *, +, -, ., /, 🙂 Binary/byte Max. 2,953 characters (8-bit bytes) (23624 bits) Kanji/Kana Max. 1,817 characters The specification … Read more