Commit 7c134033 authored by ROCA Vincent's avatar ROCA Vincent
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update of URL adding v=0 and #

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# The Cluster Exposure Verification (Cléa) Protocol: Specifications of the Lightweight Version
# The Cluster Exposure Verification (Cléa) Protocol: Specifications of Protocol Version 0
Vincent Roca, Antoine Boutet, Claude Castelluccia
......@@ -6,7 +6,7 @@ PRIVATICS team, Inria, France
{firstname.lastname}@inria.fr
**_Preliminary Draft (Work in Progress), current version, March 31st, 2021_**
**_Preliminary Draft (Work in Progress), current version, April 1st, 2021_**
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......@@ -120,7 +120,7 @@ It should be noted that technical implementation considerations (e.g., the exact
Several technical requirements, in particular motivated by the compatibility with embedded devices, have shaped the design:
- each QR code contains a country specific URL ("deep link"), composed of a contry specific prefix (for instance: `https://tac.gouv.fr/` in case of France), and a location specific part, defined in Section [Dynamic QR code generation within the device](#dynamic-qr-code-generation-within-the-device).
- each QR code contains a country specific URL ("deep link"), composed of a contry specific prefix (for instance: `https://tac.gouv.fr?v=0#` in case of France), and a location specific part, defined in Section [Dynamic QR code generation within the device](#dynamic-qr-code-generation-within-the-device).
Therefore, any binary information of the location specific part, is first translated to a printable character, using a Base64 encoding, which adds a 33% overhead compared to the binary size (see [RFC4648](#references)).
Since the output of a Base64 encoding uses an alphabet of 65 characters, it is not compatible with the Alphanumeric Mode of a QR code (limited to 45 printable characters), and it requires the use of the 8-bit Byte Mode (see [QRcode18004](#references), Section~8.4.4).
......@@ -240,10 +240,13 @@ Since the devices are not perfectly synchronized (device clock drifts), a small
The QR code of a location, at any moment, contains a URL ("deep link"), structured as:
```
"country-specific-prefix" / "Base64(location-specific-part)"
"country-specific-prefix" "Base64(location-specific-part)"
```
For instance, the country specific prefix is: `https://tac.gouv.fr/` in case of France.
This section defines the structure of the location specific part.
For instance, the country specific prefix is: `https://tac.gouv.fr?v=0#` in case of France, where:
`v=0`indicates it's protocol version 0;
the `#` character prevents the text that follows (namely the Base64 encoding of the location specific part) to be sent to the `tac.gouv.fr` server if the application is not already installed on the user terminal.
In the remaining of this section, we define the structure of the location specific part.
The QR code of a location is renewed when switching from one period to another (change of `LTKey`/`LTId`), but also periodically during the period.
This renewal during the period is automatic every `qrCodeRenewalInterval` seconds.
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