How to Convert Between Dropbear and OpenSSH Private Key Formats (with examples)

The dropbearconvert command is a versatile tool used for converting between Dropbear and OpenSSH private key formats. This functionality is crucial for systems and applications that require a specific format of SSH key. Many security and network managers encounter the need to switch between these formats to ensure compatibility with different SSH servers or clients. Having a command that seamlessly handles this conversion simplifies the workflow and reduces potential errors associated with manual conversion methods or unsupported key formats.

Convert an OpenSSH Private Key to the Dropbear Format

Code:

dropbearconvert openssh dropbear path/to/input_key path/to/output_key

Motivation:

There are several situations where converting an OpenSSH private key to the Dropbear format is necessary. For instance, when deploying lightweight, embedded systems such as routers or IoT devices that use Dropbear as their SSH client/server, you may find your infrastructure uses OpenSSH for its superior compatibility and features. Dropbear is optimized for memory-constrained environments and doesn’t support the wide range of features provided by OpenSSH. Thus, to maintain compatibility across different systems, converting OpenSSH keys to Dropbear format allows seamless integration and management of SSH access across both types of systems. This operation is also essential for users maintaining systems with mixed OpenSSH and Dropbear environments to ensure secure and efficient communication.

Explanation:

• openssh: This argument denotes the format of the input key. In this command, it specifies that the key that is to be converted originates from OpenSSH.
• dropbear: This specifies the format to which the input key will be converted. Here, the desired output is in Dropbear format.
• path/to/input_key: This is the file path to the existing OpenSSH private key that needs to be converted. It should be replaced with the actual path where your private key resides.
• path/to/output_key: This argument is the path where the converted Dropbear private key will be saved. It should be replaced with the desired path where you would like to store the new Dropbear format key.

Example Output:

Upon executing the command successfully, you should see a message indicating the conversion is complete, similarly stating, “Converted private key from OpenSSH to Dropbear format and saved to ‘path/to/output_key’.”

Convert a Dropbear Private Key to the OpenSSH Format

Code:

dropbearconvert dropbear openssh path/to/input_key path/to/output_key

Motivation:

Converting a Dropbear private key to the OpenSSH format can be especially important when scaling a network infrastructure that predominantly uses OpenSSH. With OpenSSH being the default SSH daemon for many Unix-like operating systems, including most Linux distributions, ensuring compatibility across environments is critical. OpenSSH keys may also be necessary for specific SSH features that are not supported by Dropbear, such as advanced key management, extensive configuration capabilities, and robust security features. Therefore, transitioning a Dropbear private key into an OpenSSH format facilitates broader usability and compatibility, particularly in environments transitioning from lightweight Dropbear implementations to more feature-rich OpenSSH systems.

Explanation:

• dropbear: This indicates the format of the input key. The command notes that the key to be converted originates from Dropbear.
• openssh: This specifies the desired output format for the converted key, which in this case is OpenSSH.
• path/to/input_key: This is the location of the existing Dropbear private key that needs to be converted into the OpenSSH format. You should replace it with the actual path to your current private key.
• path/to/output_key: The designated location for saving the newly converted OpenSSH private key. You would substitute this with the path where you want your new OpenSSH key to be placed.

Example Output:

When completed, confirming a message like “Converted private key from Dropbear to OpenSSH format and saved to ‘path/to/output_key’” indicates that the conversion was successful.

Conclusion

Navigating the conversion between OpenSSH and Dropbear key formats using dropbearconvert is a straightforward process once you understand the command’s structure. By accommodating these conversions, you allow for greater flexibility and compatibility within diverse IT infrastructures. These capabilities are crucial for system administrators who often work across different environments, ensuring that communication remains secure, efficient, and adaptable to various use case requirements.