CRT File Extension

What is CRT file?

Security certificates used by secure websites saved on the server to enable encrypted connection are saved in files with .CRT extensions. Security Certificates allow secure data transfer, logging, payments, or safe web browsing. CRT files are text files in ASCII encoding conforming to PEM standard.

CRT file structure

CRT files adhere to PEM and X.509 certificate standards. Base64 ASCII format determines the file encoding. Each CRT file contains the following:

• header: "—–BEGIN CERTIFICATE—–",
• Base64-encoded DER certificate,
• footer: "—–END CERTIFICATE—–".

CRT files can also use DER encoding to store the binary part of certificate.

CRT files for websites

CRT files are stored server-side. Website with valid SSL certificate, issued by Verisign or Thawte, for example, will be accepted by the web browser, which will indicate this fact by displaying a green padlock to the left of the website address. Users can check the certificate information, its holder and expiration date. CRT files can alternatively use .CER extension.

Programs which support CRT file extension

Below you will find an index of software programs that can be used to open CRT files divided into 3 categories according to system platform supported. Files with CRT suffix can be copied to any mobile device or system platform, but it may not be possible to open them properly on target system.

Updated: 04/26/2023

How to open file with CRT extension?

There can be multiple causes why you have problems with opening CRT files on given system. On the bright side, the most encountered issues pertaining to Security Certificate files aren’t complex. In most cases they can be addressed swiftly and effectively without assistance from a specialist. The following is a list of guidelines that will help you identify and solve file-related problems.

Step 1. Download and install Microsoft Internet Explorer

The most common reason for such problems is the lack of proper applications that supports CRT files installed on the system. This issue can be addressed by downloading and installing Microsoft Internet Explorer or different compatible program, such as Opera, Mozilla Firefox, Google Chrome. The full list of programs grouped by operating systems can be found above. The safest method of downloading Microsoft Internet Explorer installed is by going to developer’s website (Microsoft Corporation) and downloading the software using provided links.

Step 2. Check the version of Microsoft Internet Explorer and update if needed

If you already have Microsoft Internet Explorer installed on your systems and CRT files are still not opened properly, check if you have the latest version of the software. It may also happen that software creators by updating their applications add compatibility with other, newer file formats. The reason that Microsoft Internet Explorer cannot handle files with CRT may be that the software is outdated. The latest version of Microsoft Internet Explorer should support all file formats that where compatible with older versions of the software.

Step 3. Assign Microsoft Internet Explorer to CRT files

After installing Microsoft Internet Explorer (the most recent version) make sure that it is set as the default application to open CRT files. The method is quite simple and varies little across operating systems.

Change the default application in Windows

• Choose the Open with entry from the file menu accessed by right-mouse clicking on the CRT file
• Next, select the Choose another app option and then using More apps open the list of available applications
• Finally select Look for another app on this PC, point to the folder where Microsoft Internet Explorer is installed, check the Always use this app to open CRT files box and conform your selection by clicking OK button

Change the default application in Mac OS

• By clicking right mouse button on the selected CRT file open the file menu and choose Information
• Find the Open with option – click the title if its hidden
• Select Microsoft Internet Explorer and click Change for all...
• A message window should appear informing that This change will be applied to all files with CRT extension. By clicking Continue you confirm your selection.

Step 4. Verify that the CRT is not faulty

If you followed the instructions form the previous steps yet the issue is still not solved, you should verify the CRT file in question. It is probable that the file is corrupted and thus cannot be accessed.

1. Verify that the CRT in question is not infected with a computer virus

If the CRT is indeed infected, it is possible that the malware is blocking it from opening. It is advised to scan the system for viruses and malware as soon as possible or use an online antivirus scanner. If the CRT file is indeed infected follow the instructions below.

2. Verify that the CRT file’s structure is intact

Did you receive the CRT file in question from a different person? Ask him/her to send it one more time. It is possible that the file has not been properly copied to a data storage and is incomplete and therefore cannot be opened. It could happen the the download process of file with CRT extension was interrupted and the file data is defective. Download the file again from the same source.

3. Verify whether your account has administrative rights

There is a possibility that the file in question can only be accessed by users with sufficient system privileges. Log out of your current account and log in to an account with sufficient access privileges. Then open the Security Certificate file.

4. Verify that your device fulfills the requirements to be able to open Microsoft Internet Explorer

If the systems has insufficient resources to open CRT files, try closing all currently running applications and try again.

5. Check if you have the latest updates to the operating system and drivers

Latest versions of programs and drivers may help you solve problems with Security Certificate files and ensure security of your device and operating system. It may be the case that the CRT files work properly with updated software that addresses some system bugs.

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