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Fixing SSL Certificate Error in Ubuntu 20.04 Upgrade

Ubuntu 20

In the process of upgrading to Ubuntu 20.04, you may encounter SSL certificate errors when attempting to make HTTP calls. A common error message you might come across is: “error: Error: [(‘SSL routines’, ‘SSL_CTX_use_certificate’, ‘ca md too weak’)].” This error is usually triggered due to the use of a weak message digest (hash function) in the certificate, specifically SHA-1.

This article will guide you through the steps to resolve this issue. We’ll cover two main solutions: updating your code to use a stronger message digest algorithm, and modifying the OpenSSL configuration file.

Quick Answer

To fix the SSL certificate error in Ubuntu 20.04 upgrade, you can either update your code or certificate to use a stronger message digest algorithm (SHA-256) or modify the OpenSSL configuration file to lower the SSL security level (not recommended).

Understanding the Error

Before we dive into the solutions, it’s important to understand the error. The error message “ca md too weak” indicates that the certificate is using a weak hash function, SHA-1. SHA-1 is considered insecure and is being phased out in favor of more secure algorithms like SHA-256.

Solution 1: Updating Your Code to Use a Stronger Message Digest Algorithm

The first and most recommended solution is to update your code or certificate to use a stronger message digest algorithm. Here’s how to do it:

  1. Open your certificate file in a text editor of your choice.
  2. Locate the line that specifies the message digest algorithm. It might look something like this: Signature Algorithm: sha1WithRSAEncryption.
  3. Replace sha1WithRSAEncryption with sha256WithRSAEncryption. This changes the message digest algorithm from SHA-1 to SHA-256.
  4. Save and close the file.

Solution 2: Modifying the OpenSSL Configuration File

If updating your code is not an option, you can modify the OpenSSL configuration file to lower the SSL security level. This will allow your system to accept certificates with weaker message digests.

Please note: Lowering the SSL security level is not recommended as it compromises the security of your system. Use this solution only as a last resort.

Here’s how to modify the OpenSSL configuration file:

  1. Open the OpenSSL configuration file in a text editor. The file is usually located at /etc/ssl/openssl.cnf.
  2. Add the following section to the file:
[system_default_sect]
MinProtocol = TLSv1.2
CipherString = DEFAULT:@SECLEVEL=1

This sets the minimum protocol version to TLSv1.2 and the cipher string to allow weaker security levels.

  1. Save and close the file.

Conclusion

While encountering SSL certificate errors can be frustrating, they are usually easy to fix. The solutions provided in this article should help you resolve the “ca md too weak” error in Ubuntu 20.04. Remember, it’s always best to use a stronger message digest algorithm whenever possible to ensure the security of your system. If you’re still having trouble, consider reaching out to the Ubuntu community or a professional for help.

What is an SSL certificate error?

An SSL certificate error occurs when there is an issue with the digital certificate that is used to establish a secure connection between a web server and a client. It indicates that the certificate is invalid, expired, or not trusted by the client’s browser or operating system.

Why am I encountering an SSL certificate error during the Ubuntu 20.04 upgrade?

During the Ubuntu 20.04 upgrade, SSL certificate errors can occur if the upgrade process triggers the use of a weak message digest (hash function) in the certificate, specifically SHA-1. SHA-1 is considered insecure and is being phased out in favor of more secure algorithms like SHA-256.

How can I update my code to use a stronger message digest algorithm?

To update your code to use a stronger message digest algorithm, you need to modify the certificate file. Open the certificate file in a text editor, locate the line that specifies the message digest algorithm (e.g., Signature Algorithm: sha1WithRSAEncryption), and replace sha1WithRSAEncryption with sha256WithRSAEncryption. Save the file and the code will now use the stronger SHA-256 algorithm.

What should I do if updating my code is not an option?

If updating your code is not possible, you can modify the OpenSSL configuration file to lower the SSL security level. This allows your system to accept certificates with weaker message digests. However, it is not recommended as it compromises the security of your system. Use this solution only as a last resort.

Where can I find the OpenSSL configuration file in Ubuntu?

The OpenSSL configuration file is usually located at /etc/ssl/openssl.cnf in Ubuntu. You can open this file in a text editor to make the necessary modifications as mentioned in the solution.

Is it safe to lower the SSL security level in the OpenSSL configuration file?

Lowering the SSL security level is not recommended as it compromises the security of your system. We suggest using this solution only as a last resort. It is always best to update your code or certificate to use a stronger message digest algorithm whenever possible to ensure the security of your system.

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