title: Win10 OpenSssh: ssh-add gives err "invalid format" for key file
body: <p>On windows 10, the ssh-add commant is giving the following error:
  <code>Could not add identity &quot;C:\users\&lt;username&gt;\.ssh\id_rsa_win&quot;: invalid format</code></p>
  <p>I generated the key like this: <code>ssh-keygen -t rsa -N 'my pass phrase' -C 'generated by windows openssh' -f C:\Users\&lt;username&gt;\.ssh\id_rsa_win</code></p>
  <pre><code>Get-Command ssh-keygen
  
  CommandType     Name                                               Version    Source
  -----------     ----                                               -------    ------
  Application     ssh-add.exe                                        7.7.2.1    C:\Windows\System32\OpenSSH\ssh-add.exe
  </code></pre>
  <pre><code>Get-Command ssh-add
  
  CommandType     Name                                               Version    Source
  -----------     ----                                               -------    ------
  Application     ssh-add.exe                                        7.7.2.1    C:\Windows\System32\OpenSSH\ssh-add.exe
  </code></pre>