Home / server / Questions / 52285
Accepted
Amandasaurus
Asked: 2009-08-11 06:36:15 +0800 CST

Create a public SSH key from the private key?

  • 772

Let's suppose I have a SSH key, but I've deleted the public key part. I have the private key part. Is there some way I can regenerate the public key part?

ssh encryption public-key private-key

2 Answers

  1. Best Answer

    Use the -y option to ssh-keygen:

    ssh-keygen -f ~/.ssh/id_rsa -y > ~/.ssh/id_rsa.pub

    From the 'man ssh-keygen'

     -y      This option will read a private OpenSSH format file and print an
         OpenSSH public key to stdout.

    Specify the private key with the -f option, yours might be dsa instead of rsa. The name of your private key probably contains which you used. The newly generated public key should be the same as the one you generated before.

    • 327

  2. Solution is specifically for users using Windows

    Tool Used:

    • Puttygen (PuTTY Key Generator)
    • WinSCP

    Steps to perform:

    1. Open PuTTY Key Generator.
    2. Load your private key (*.ppk file).
    3. Copy your public key data from the "Public key for pasting into OpenSSH authorized_keys file" section of the PuTTY Key Generator and paste the key data to the "authorized_keys" file (using notepad) if you want to use it.

    Snapshot showing portions of Puttygen to focus:

    Snapshot showing portions of Puttygen to focus

    • 7