Sourcetree shows SSH fingerprint in different format

Summary

• This knowledge article explains why the SSH key may show in a different format than expected within the Sourcetree application, and provides a solution for this.

Diagnosis

• Sourcetree shows the following message when attempting to authenticate over SSH, the SSH key's fingerprint is shown in MD5 format by default:

  

Cause

• SSH fingerprints can be parsed in different ways using different algorithms. 

  • The 2 different algorithms covered in this page are MD5 and SHA256 

  • By default, most of the Linux based operating systems with SSH prefer SHA256 format whereas some clients such as Sourcetree prefer MD5 format. 

• Although the SSH key shown in the screenshot is correct, the fingerprint is in a different format and doesn't match as mentioned in this article because of the algorithm used to parse the SSH key.

• Sourcetree uses MD5 format by default and hence the fingerprint's format looks different. 

• The below command fetches the SSH key fingerprint in MD5 format. In the below commands, the file "Bitbucket_Knownhost" contains the RSA type SSH known host key of bitbucket.org.

• Whereas, the below command fetches the SSH key fingerprint in SHA256 format

Solution

• Both the formats SHA256 and MD5 are widely used and are recognised by SSH.

• The difference in formats is due to the git version used by Sourcetree compared to your PC/server. 

  • Sourcetree uses Embedded git by default and the configuration of this git version could be different from your local git version. 

  • You can configure Sourcetree to use your local git settings by following the steps contained within this article which covers the topic.