The American Standards Association (ASA), now the American National Standards Institute (ANSI), began work on ASCII on October 6, 1960. The encoding scheme had origins in the 5-bit telegraph codes invented by Émile Baudot. The committee eventually decided on a 7-bit code for ASCII.

7 bits allow for 128 characters. While only American English characters and symbols were chosen for this encoding set, 7 bits meant minimized costs associated with transmitting this data (as opposed to say, 8 bits).

The first 32 characters of ASCII were reserved control characters. These characters were used to relay special instructions to other devices, like printers. For example, a user could advance a line, delete a character, and on some devices, ring a bell (such as on the Teletype Model 33 ASR).

ASA published the first version of ASCII in 1963 and revised it in 1967. The last major update to the standard occurred in 1986. ASCII first saw commercial use in the American Telephone & Telegraph (AT&T) TeletypeWriter Exchange (TWX) network.

The Digital Green Certificate comes in to facilitate safe and free movement.

Commission Implementing Decision (EU) 2021/2014 of 17 November 2021 amending Implementing Decision (EU) 2021/1073 laying down technical specifications and rules for the implementation of the trust framework for the EU Digital COVID Certificate established by Regulation (EU) 2021/953 of the European Parliament and of the Council (Text with EEA relevance)

News announcement | 3 May 2022

Base45/Zlib/COSE/CBOR is CBOR format data signed in COSE format, compressed in Zlib format, and converted to Base45 format.

EUDCC (EU Digital COVID Certificate) is used as the data format for QR codes. EUDCC is the common format for the COVID-19 vaccination certificate in the EU, also known as DGC (EU Digital Green Certificate) or Green Pass.

DenCode supports decoding only, and the decoded result is expressed in JSON format. The validity of the signature is not verified.

In a podcast geared towards CTOs, Matthias Jugel, the CTO of UBIRCH shared what went into the technology and explained how to simply decode the content of the QR-Code.

Commission Implementing Decision (EU) 2021/1073 of 28 June 2021 laying down technical specifications and rules for the implementation of the trust framework for the EU Digital COVID Certificate established by Regulation (EU) 2021/953 of the European Parliament and of the Council (Text with EEA relevance)

Commission Implementing Decision (EU) 2021/1073 of 28 June 2021 laying down technical specifications and rules for the implementation of the trust framework for the EU Digital COVID Certificate established by Regulation (EU) 2021/953 of the European Parliament and of the Council (Text with EEA relevance)

Littledata surveyed 5,985 sites in May 2022 and found the average server response time was 416ms.

Based on the public EU technical specifications, here is a simple decoder of the QR-code, it displays all the information in the Health Certificate QR-code with many technical explanations on the steps. A lot of the technique used by the EU Green Certificate are coming from the IETF. The code itself is heavily based on open source code.

This repository contains a proposal for encoding and signing the Electronic Health Certificate (HCERT), as a candidate to be adapted and adopted by eHealth authorities and other stakeholders as they see fit.

Commission Implementing Decision (EU) 2021/2301 of 21 December 2021 amending Implementing Decision (EU) 2021/1073 laying down technical specifications and rules for the implementation of the trust framework for the EU Digital COVID Certificate established by Regulation (EU) 2021/953 of the European Parliament and of the Council (Text with EEA relevance)