SSH, or Secure Shell, is a protocol used to securely log onto remote systems. It is the most common way to access remote Linux and Unix-like servers. SSH uses public-key cryptography to authenticate the remote computer and allow the remote computer to authenticate the user, if necessary.
In this article, we will discuss how to retrieve the public key from an SSH private key.
To retrieve the public key from an SSH private key, you can use the
ssh-keygen tool or a text editor. With
ssh-keygen, you can simply run the command
ssh-keygen -y -f ~/.ssh/id_rsa > ~/.ssh/id_rsa.pub to extract the public key. Alternatively, you can open the private key file in a text editor, copy the content starting with
ssh-rsa, and paste it into a new file named
Overview of SSH Keys
SSH keys are a pair of cryptographic keys that can be used to authenticate to an SSH server as an alternative to password-based logins. A private key, which is secret, is used to decrypt data and a public key, which is shared, is used to encrypt data.
Retrieving Your Public Key
In some cases, you might have the private key but have lost the public key. You can easily retrieve the public key if you have the private key. Here’s how:
Method 1: Using ssh-keygen
ssh-keygen tool is a part of the OpenSSH package and is used to create new key pairs. You can also use it to extract the public key from the private key.
Here is the command you can use:
ssh-keygen -y -f ~/.ssh/id_rsa > ~/.ssh/id_rsa.pub
Let’s break down this command:
ssh-keygenis the command for creating new authentication key pairs.
-yoption is used to read a private SSH key file and print an associated public key.
-foption specifies the filename of the key file.
~/.ssh/id_rsais the default filename of the private key. You can replace this with your actual private key file path.
> ~/.ssh/id_rsa.pubis used to redirect the output to the
id_rsa.pubfile. This will be your public key.
Method 2: Using a Text Editor
You can also use a text editor to retrieve the public key from the private key. Here’s how:
- Open the private key file (
id_rsa) in a text editor.
- Copy the content of the file, which starts with
ssh-rsaand ends with your username or a comment.
- Create a new file called
~/.ssh/directory (if it doesn’t exist).
- Paste the copied content into the
- Save the file.
Additional Steps for Windows Users
If you are using Windows and need to SSH into remote machines, you can follow these additional steps:
- Download and install the
puttygentool from here.
puttygenand load your private key file (
- Copy the public key from the “Public key for pasting into OpenSSH authorized_keys file” section.
- Create or open the
authorized_keysfile on the remote server.
- Paste the copied public key into the
- Save the file.
Remember to set the correct permissions for the
~/.ssh/ directory and the
authorized_keys file on the remote server. You can use the
chmod command for this.
In this article, we have discussed how to retrieve the public key from an SSH private key. We have discussed two methods using
ssh-keygen and a text editor. We have also discussed additional steps for Windows users.
Remember, your private key is like your password. You should keep it secure and never share it with anyone. If you believe your private key has been compromised, you should generate a new pair of SSH keys.
If you have any further questions or need more information, you can refer to the OpenSSH manual or the PuTTYgen manual.
No, you need the private key file in order to retrieve the public key. If you have lost the private key file, you will need to generate a new pair of SSH keys.
Yes, you can use any text editor to retrieve the public key from the private key. Just make sure to follow the steps mentioned in the article, such as copying the content starting with
ssh-rsa and ending with your username or a comment, and saving the file with the
.pub extension in the
Yes, it is possible to retrieve the public key from the private key on a Windows machine. You can use the
puttygen tool as mentioned in the article. Follow the steps provided to load your private key file, copy the public key, and paste it into the
authorized_keys file on the remote server.
The additional steps for Windows users are mentioned in the article. You need to download and install the
puttygen tool, load your private key file, copy the public key from the "Public key for pasting into OpenSSH authorized_keys file" section, and paste it into the
authorized_keys file on the remote server. Remember to set the correct permissions for the
~/.ssh/ directory and the
No, you should never share your private key with anyone. Your private key is like your password and should be kept secure. Sharing your private key can compromise the security of your SSH authentication.