Frequently asked questions on the applications čTečka and Tečka

FAQ categories:

Certificates’ details, reasons for invalid certificates and error warnings ↓

Why does the Dot show me everything in red?

Please click the yellow bar below and then the update button. We have updated all systems and applications in the application to validate important parameters as they currently apply.

Basic information

For whom is Tečka?

Tečka is an application for certificate holders, i.e., for people who want to certify their vaccination, past disease, or a negative test.

For whom is čTečka?

čTečka is an application to verify a certificate. It is intended for government officials, service, or event providers to whom verification of certificates is imposed as protective measures by the Ministry of Health.

What should I do if I forgot my PIN for the application Tečka?

It is not a problem. If you forget your PIN, you simply delete the application from your phone and install it again.

After the reinstallation, enter a new PIN. You can also use a fingerprint or face scan (in case the phone supports biometric data, it should be enabled on the device).

Important: after the reinstallation, it will be necessary to add your certificates again. The fastest way is either via a one-time SMS, eidentita, or a QR code.

What is the correct way to use čTečka for certificates verification?

Validity of certificates, or rather of QR codes, is verified by the verifier’s (police, service providers, or event organizers) own application čTečka, or a similar application from other countries. These applications are freely available and easy to use. Other government and private organizations can create their own verification applications – the technical standards for that are publicly available.

To confirm a certificate’s validity by a QR code reader, the electronic signature is verified (in case the certificate is issued by an authorized person and is not fake) and is furthermore validated in compliance with the state’s regulations, i.e., time validity, recognized types of PCR tests, etc.

For complete verification, it is also necessary to confirm the identity of the certificate holder, for example by checking their ID to make sure it is the same person for whom the certificate was issued (by the name and date of birth).

What is the experience with certificates verification in practice and what is the reaction from the Ministry of Health?

The Ministry of Health appeals to all service and event providers under obligation to verify certificates in compliance with the Covid protective measures to use the application čTečka. Organizers of large events in need to integrate čTečka’s functionality into their information and verification / entry systems or having specific requirements for čTečka’s functionality will be provided consultations and even modification of the application, upon request.

Furthermore, in the updated versions of čTečka we implemented a number of functions thanks to which the application became more user friendly even in case the verifier does not follow the correct procedure (e.g., displaying the Details page in English, neutral colouring of the Certificate page). We are working on a function for certificates to be displayed or sent in PDF Format directly from Tečka.

Why are the mobile applications for Digital COVID certificates called Tečka and čTečka?

The names refer to the campaign “udělejme TEČKU za epidemií” (let’s put the pandemics behind us) by the Ministry of Health of the Czech Republic.

How do I find the applications in Apple Store and Google Play Store?

If you are looking for the applications by the names, we would recommend using a combination of words, as the names correspond to frequently used words. For example, you could type ”čtečka Covid” or “čTečka Ministerstvo zdravotnictví” if simply entering the names of the applications does not work.
The čTečka application’s icon is a white circle inside a yellow box saying ČTEČKA.
The Tečka application’s icon is a yellow circle inside a white box saying TEČKA.

On what phones do čTečka and Tečka work?

The applications are available for mobile phones with Android operating systems of version 6 and higher, and iOS operating systems version 12 and higher.
The mobile applications are distributed via Apple Store and Google Play Store. They cannot be installed on Android phones that do not support Google Play Store, e.g., the latest Huawei phones.

General functionalities

What can the application čTečka do?

The application čTečka is intended for verification of Digital COVID certificates (the “Verifier”, in EU standards terminology) providing the following:

downloads configuration – signature keys (EU countries) and validation regulations (Czech Republic only) from the IHIS CR server (once every 24 hours);
scans QR codes, verifies electronic signatures, verifies validity in compliance with the validation regulations (can be done offline);
provides an overview and detailed information from the certificate;
retrieves and provides information from the original vaccination certificate which will be, however, marked as invalid (its validity cannot be verified due to it not following EU standards).

What can the application Tečka do?

The application Tečka is intended for downloading and displaying certificates (the “Wallet”, in EU standards terminology) providing the following:

login via Identita občana (formerly eidentita.cz, also known as Národní Bod or NIA). the first time, and later only via a fingerprint, face recognition or a PIN;
an alternative login via a one-time SMS passcode (same as at ocko.uzis.cz) the first time, and later only via a fingerprint or face recognition, or a PIN;
supports viewing certificates of multiple people;
uploads existing certificates from ocko.uzis.cz;
scans certificates off paper or a displayed QR code of the holder or other people;
converts an original vaccination certificate into the EU format;
when displaying certificates, affirms their validity in compliance with the validation regulations (can be done offline);
provides an overview and detailed information from the certificate;
downloads configuration – signature keys (EU countries) and validation regulations (for the Czech Republic only) from the IHIS CR server (once every 24 hours).

How to verify Ticketportal tickets using the application Tečka?

Follow the instructions here (in Czech language).

What is new in the updated versions of čTečka and Tečka?

Tečka version 1.1 (middle of July):

Option to switch the language of the Details page to English
Increased brightness of the Certificate page

Tečka version 1.2 (beginning of August):

Neutral background lighting for the Certificate and Details pages
Vaccination certificate validity changed to “no restrictions” (will be implemented with the release of the application’s new version)
Option to add a certificate from a QR code image or PDF file saved on a mobile phone
The certificates retrieved from QR codes are highlighted (to notify that they are not updated)
Option to delete certificates retrieved from QR codes
Limited number of certificates retrieved from QR codes
Optimized accessibility for the visually challenged
Application updates notifications
Minor bug fixes and optimizations

čTečka version 1.2 (middle of July):

Marking the original vaccination certificates in yellow as Invalid

čTečka version 1.3 (beginning of August):

Jingle / vibration when scanning QR codes
Option to add backlighting when scanning a QR code
Optimized accessibility for the visually impaired
Minor bug fixes and optimizations

Why did certificates “turn blue” in the version 1.2 of Tečka?

Marking certificates in green and red in compliance with the Covid protective measures in force in the Czech Republic was intended for the certificate holder’s general reference. In practice, unfortunately, it was frequently used incorrectly by verifiers – instead of using their own QR code reader, they relied on the colours in Tečka.

Colouring of the certificates in green and red lead to incorrect interpretation of certificates’ validity in some cases when checked abroad (for example, in Austria where the rules for a certificate’s recognition are looser after the second vaccination dose) and, in general, supported such incorrect verification method. Therefore, neutral (blue) background colouring was implemented for the pages that are to be presented for verification (the pages Certificate and Details).

We left marking of certificates in green and red only in the list of persons and list of certificates of the primary holder for them to view and select certificates. The details for verification of validity in compliance with the Covid protective measures in force in the Czech Republic, including possible reason for invalidity, could be found on the page Details below.

Why are the certificates scanned from QR codes have yellow colouring in the lists in the version 1.2. of Tečka?

The certificates added to Tečka via scanning a QR code have limited functionality. They are not automatically updated, e.g., after the second vaccination dose or a more recent test, and thus have different colouring in the list of certificates.

Automatic update is for certificates added from the Vaccination Portal with the help of eidentity or an SMS passcode, which are the recommended and proper methods of logging in and retrieving certificates (you will find the instruction how to use the Vaccination Portal here).

Upwards of the version 1.2, Tečka also supports scanning QR codes from an image saved in a mobile device or from a PDF file attached to an email.
In the version 1.2 and upwards, the number of certificates retrieved from QR codes was limited (currently, it is 10 certificates). The reason for that was to avoid cumulation of old and other people’s certificates in the application. The number of certificates uploaded from the server after the proper login (eidentity or an SMS passcode) is not limited.

Does the application need Internet connection?

Only to update loaded certificates or validation verification parameters, but not for browsing and viewing of loaded certificates.

What will the application require to have access to on my phone?

To camera only.

How to switch the language of the applications Tečka and čTečka?

The applications support Czech and English. The language of the application is by default selected according to the language setting of the operating system. iOS allows to change the language for the application in the Settings. For that, scroll down in the settings of individual apps and select Tečka or čTečka to change the language.

What is Update Parameters?

Validity verification parameters, i.e., signature certificates of EU countries, current validity regulations (number of days after the first/second vaccination dose, etc.), are updated when the application is open if they are older than 24 hours. You can also click on the button “Update parameters” for that. The application can still be used with outdated parameters.

Uploading and storing certificates

How fast is a Digital COVID certificate issued?

Vaccination certificates (the first and second doses) are usually issued within a few minutes after the vaccination, or rather when the record on the vaccination in the ISIN OČKO is made at a vaccination site.
A certificate of a taken PCR test is issued only after the laboratory tests are performed and the results are delivered to central systems. The laboratory tests can take up to 48 hours after the actual collection. It is not guaranteed that an SMS with the results, sent directly by the laboratory, is received by you at the same moment as the results are sent to the central system. After receiving an SMS with the results, the certificate issuing can take a few more hours (up to half a day).
A certificate of a past disease is issued based on a positive PCR test. The certificate is available on the 11th day after a positive PCR test.

What does the error “Could not recognize the QR code format” appearing on the page with the camera mean?

The application recognized that it is a QR code, but the data in it does not have correct structure according to the EU standard. It is either a QR code for different use or it has a poorly structured EU certificate that cannot be scanned in full or be verified.

Do the applications store information from certificates?

The application čTečka only displays information on the screen of a device. Contrarily, Tečka’ s purpose is long-term storing of the information from certificates.
More information on personal data protection for the application čTečka could be found here, and for Tečka here.

Can the application upload certificates issued by other countries?

Yes, certificates in the EU Digital COVID Certificate format can be loaded into the application. The application currently verifies validity of all stored certificates in compliance with the Czech validity regulations (number of days after the first/second vaccination dose, etc.).

How to initiate update for the certificates stored in the application Tečka?

Updated or new certificates (e.g., new test certificates, certificate for the second vaccination dose, etc.) for persons logged in via eidentita.cz or via an SMS code from ocko.uzis.cz can be updated by “scrolling the screen down” on the page containing the list of persons or certificates.

Certificates’ details, reasons for invalid certificates and error warnings

Why is the name mentioned 2x in the certificate’s details?

The first time, the name includes diacritics (it is written in the national alphabet of a given state). The second time, it is an international version without diacritics.

What are reasons for a certificate to be invalid?

it may contain an incorrect data format (in such case it cannot be scanned at all and the data from it cannot be retrieved)
the electronic signature cannot be verified (specific reasons are coded in SIGxxx error codes)
it does not comply with the validity regulations (number of days after the first/second vaccination dose, etc.)
it might be an original version of vaccination certificate issued before 1.6. (it is always marked as invalid)

The reason for a certificate being invalid is always listed in the screen Details.
Even if a certificate is invalid, the information from it is listed on the screen Details when it is technically possible to obtain it.

What are the meanings of the reasons for a certificate being invalid listed on the page Details?

The reasons for a certificate being invalid shown on the Details page are as follows:

The electronic signature of the certificate cannot be verified – see the following question
The certificate is invalid – revoked – the certificate was marked as invalid by the issuer, it was probably issued by mistake
The validity of the vaccination certificate has not yet started or has already expired – check the vaccination date and the validity period listed on the Details page – they are calculated based on the validity regulations (22 days after the first dose, etc.)
The validity of the certificate of past disease has not yet started or already expired – check the date of the positive PCR test and the validity period on the Details page – they are calculated based on the validity regulations (180 days after the test, etc.)
The test certificate is no longer valid – check the date of collection and the validity period on the Details page – they are calculated based on the validity regulations (72 hours for an AG test, etc.)
It is the original version of a vaccination certificate – it is always marked as invalid, see the answer above.

What is the meaning of the error codes SIGxxx, when an electronic signature cannot be verified?

In the vast majority of cases, electronic signature verification error codes indicate a technical problem with the content of a QR code caused by its issuer.
However, they may also indicate an attempt to forge a QR code, and the electronic signature’s purpose is to protect QR code from that.

The detailed technical meaning of the separate codes is as follows:

SIG001 – Information on expiration is missing in COSE
SIG002 – COSE has expired
SIG003 – KID is missing in COSE (public key identifier)
SIG004 – Active signing certificate for KID could not be found
SIG005 – Failure to extract the key from the certificate’s data
SIG006 – Wrong signature data in COSE
SIG007 – Failure to verify the signature

The error SIG002 refers to expiration date of technical validity of the entire certificate set by the certificate authority (it is not connected to the validity of the health condition certificate). The validity is set to 1 year for certificates issued in the Czech Republic.

The error SIG004 means that the application could not find the relevant signature key in the parameters downloaded from IHIS CR. It might be a technical problem on the side of the certificate authority, a problem with transferring communication between the issuing country and the Czech Republic via EU communication gateway, or a problem with updating parameters between the application and IHIS CR. In some cases, it can be resolved by pressing the button “Update parameters”.

The application support cannot furthermore diagnose an error without the problematic QR code that could be provided, for example, as an image by email.