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Fixing SSH ed25519-sk Key Generation Error in Ubuntu 20.04

Ubuntu 5

In this article, we will delve into a common issue faced by Ubuntu 20.04 users when attempting to generate an ed25519-sk SSH key, especially with a Google Titan key. We will discuss what the issue is, why it occurs, and how to resolve it.

Quick Answer

To fix the SSH ed25519-sk key generation error in Ubuntu 20.04, you can try generating an ecdsa-sk SSH key instead using the ssh-keygen command with the -t ecdsa-sk option. It is important to use a key algorithm that is supported by your hardware key to ensure compatibility and security.

Understanding the Issue

When you attempt to generate an ed25519-sk SSH key using a Google Titan key on Ubuntu 20.04, you might encounter an error message indicating that the key enrollment failed due to an invalid format. This error message suggests that the Google Titan key may not support the ed25519-sk algorithm.

Why Does This Issue Occur?

The ed25519-sk and ecdsa-sk are types of SSH key algorithms. They are used to generate public and private keys for secure shell (SSH) protocol, which is used for secure remote logins and other secure network services over an insecure network.

The Google Titan key might not support the ed25519-sk algorithm, which is why you’re encountering the error. This is not an isolated case, as there have been reports of similar errors with YubiKeys and other hardware keys.

How to Confirm the Issue

To confirm whether the Google Titan key supports the ed25519-sk algorithm, you can refer to the official Google Titan key documentation or contact Google support. If the key does not support ed25519-sk, you may need to use the ecdsa-sk algorithm instead for generating SSH keys.

Fixing the Issue

If the Google Titan key does not support ed25519-sk, there may not be a workaround for this limitation. It is important to use a key algorithm that is supported by your hardware key to ensure compatibility and security. Here’s how you can generate an ecdsa-sk SSH key instead:

  1. Open your terminal.
  2. Run the following command:
ssh-keygen -t ecdsa-sk

This command initiates the generation of an SSH key pair using the ecdsa-sk algorithm. The -t option specifies the type of key to create.

Follow the prompts to complete the key generation process.

Conclusion

While it may be frustrating to encounter the ed25519-sk key generation error in Ubuntu 20.04, understanding the cause of the issue and how to resolve it can help you navigate this challenge. If you require further assistance or clarification, it is recommended to consult the official documentation or contact Google support. Remember, it’s crucial to use a key algorithm that is supported by your hardware key to ensure compatibility and security.

Can I generate an `ed25519-sk` SSH key using a Google Titan key on Ubuntu 20.04?

No, it is likely that the Google Titan key does not support the ed25519-sk algorithm. You may need to use the ecdsa-sk algorithm instead.

How can I confirm if the Google Titan key supports the `ed25519-sk` algorithm?

To confirm, you can refer to the official Google Titan key documentation or contact Google support for more information on the supported algorithms.

What other hardware keys might encounter similar issues with `ed25519-sk` key generation?

There have been reports of similar errors with YubiKeys and other hardware keys. It is recommended to consult the documentation or support for your specific hardware key to determine the supported algorithms.

Is there a workaround for the limitation of `ed25519-sk` key generation in Ubuntu 20.04?

If the Google Titan key does not support ed25519-sk, there may not be a workaround for this limitation. It is important to use a key algorithm that is supported by your hardware key to ensure compatibility and security.

How can I generate an `ecdsa-sk` SSH key instead?

To generate an ecdsa-sk SSH key, open your terminal and run the following command: ssh-keygen -t ecdsa-sk. Follow the prompts to complete the key generation process.

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