Generate A Public Key From Private Ssh Key

Puttygen generate ssh key windows. Working with PuTTY's Public Key Format. Open PuTTYgen. Next to Load an existing private key file, click the Load button. Navigate to the private key in your file system and select it. PuTTYgen is an key generator tool for creating SSH keys for PuTTY. It is analogous to the ssh-keygen tool used in some other SSH implementations. The basic function is to create public and private key pairs. PuTTY stores keys in its own format in.ppk files. However, the tool can also convert keys to and from other formats.

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Usually a public SSH key is generated at the same time as a private key. Unlike a private SSH key, it is acceptable to lose a public key as it can be generated again from a private key at any time. In this small note i am showing how to create a public SSH key from a private one using ssh. Turns out the old version of ssh on this server doesn't generate the public key from the private key, it reads the idrsa.pub file to send the public key. Since this public key doesn't match what's in authorizedkeys, I was denied. The solution was to delete the public key. Alternatively, you can generate the public key with ssh-keygen. I'm trying to store (append) the public key to a file (/.ssh/authorizedkeys) for a private key (private-key.pem) that actually is stored in s3, all using bash script. Retrieving public key using a. To generate an SSH private/public key pair using the ssh-keygen command and then copy the public key to your clipboard for use, complete the following steps: On your local computer, open a command-prompt window. Ensure you do not already have a public key saved to your computer. Generate online private and public key for ssh, putty, github, bitbucket Save both of keys on your computer (text file, dropbox, evernote etc)!!! The generated keys are RANDOM and CAN'T be restored.

SSH allows for both password based authentication, as well as public key authentication. Public key authentication is generally regarded as being more secure, as it isn’t as prone to brute force login attempts (if you disable password based authentication). The private key can also have a passphrase associated with it, which makes public key authentication even more secure if needed.
Sometimes cloud servers will let you put a public key in as a authorized authentication key when the cloud server is created, preventing the need for password based authentication to be enabled by default.
Generate a new SSH public and private key pair:

“Identifying comment” can be any string that will assist in determining which key this is. “username@hostname” of the machine where you are connecting from would be a good example.
eg:

This will generate two files, “keypair” and “keypair.pub”. “keypair” being the private key that you need to keep secure, and “keypair.pub” being the public key, that can be put on servers that you want to be able to log into with the private key.
Change the filename to suit your needs. This example uses “keypair” for the examples.
The contents of the public key file “keypair.pub” can be inserted into the ~/.ssh/authorized_keys file on the machine that you want to be able to connect into remotely. This must be done for the specific user.
Insert public key into authorized keys
View the contents of the public key file:

eg:

Take note of the output, and copy it into the clipboard if possible, or use some other method to get this file/data onto the remote machine, as it will be used in the next step.
On the remote server you want to be able to log into:

If you have chosen to copy the public key file to the remote host instead, you can issue the following command instead:

Logging into remote ssh server using the private key file
To connect to the remote host using SSH you can use the following command:

This will use the private key called “keypair” created earlier, and assuming the remote server has the public key added to the “user” users authorized_keys file, you should be able to log into the remote system.

Several tools exist to generate SSH public/private key pairs. The following sections show how to generate an SSH key pair on UNIX, UNIX-like and Windows platforms.

To extract public key from the private key file into separate public key file you use your openssl rsa -in private.pem -pubout -out public.pem command. When you produce a public key this way, it is extracted from the private key file, not calculated. See my answer below for more details. – golem Jun 4 '17 at 17:27 show 12 more comments. Aug 29, 2016  If you want to use public key encryption, you’ll need public and private keys in some format. OpenSSL and many other tools can generate such key pairs as well as java. However, if it comes to interoperability between these tools, you’ll need to be a bit careful. Openssl rsa public and private key generation using java.

Generating an SSH Key Pair on UNIX and UNIX-Like Platforms Using the ssh-keygen Utility

UNIX and UNIX-like platforms (including Solaris and Linux) include the ssh-keygen utility to generate SSH key pairs.

1. Navigate to your home directory:
2. Run the ssh-keygen utility, providing as filename your choice of file name for the private key:

   The ssh-keygen utility prompts you for a passphrase for the private key.

3. Enter a passphrase for the private key, or press Enter to create a private key without a passphrase:

   Note:

   While a passphrase is not required, you should specify one as a security measure to protect the private key from unauthorized use. When you specify a passphrase, a user must enter the passphrase every time the private key is used.

   The ssh-keygen utility prompts you to enter the passphrase again.

4. Enter the passphrase again, or press Enter again to continue creating a private key without a passphrase:
5. The ssh-keygen utility displays a message indicating that the private key has been saved as filename and the public key has been saved as filename.pub. It also displays information about the key fingerprint and randomart image.

Generating an SSH Key Pair on Windows Using the PuTTYgen Program

The PuTTYgen program is part of PuTTY, an open source networking client for the Windows platform.

Generate Public Key From Private Ssh-keygen

Generate A Public Key From Private Ssh Key Generator

Generate A Public Key From Private Ssh Key Mac

1. Download and install PuTTY or PuTTYgen.

   To download PuTTY or PuTTYgen, go to http://www.putty.org/ and click the You can download PuTTY here link.

2. Run the PuTTYgen program.
3. Set the Type of key to generate option to SSH-2 RSA.
4. In the Number of bits in a generated key box, enter 2048.
5. Click Generate to generate a public/private key pair.

   As the key is being generated, move the mouse around the blank area as directed.

6. (Optional) Enter a passphrase for the private key in the Key passphrase box and reenter it in the Confirm passphrase box.

   Note:

   While a passphrase is not required, you should specify one as a security measure to protect the private key from unauthorized use. When you specify a passphrase, a user must enter the passphrase every time the private key is used.

7. Click Save private key to save the private key to a file. To adhere to file-naming conventions, you should give the private key file an extension of .ppk (PuTTY private key).

   Note:

   The .ppk file extension indicates that the private key is in PuTTY's proprietary format. You must use a key of this format when using PuTTY as your SSH client. It cannot be used with other SSH client tools. Refer to the PuTTY documentation to convert a private key in this format to a different format.
8. Select all of the characters in the Public key for pasting into OpenSSH authorized_keys file box.

   Make sure you select all the characters, not just the ones you can see in the narrow window. If a scroll bar is next to the characters, you aren't seeing all the characters.

9. Right-click somewhere in the selected text and select Copy from the menu.
10. Open a text editor and paste the characters, just as you copied them. Start at the first character in the text editor, and do not insert any line breaks.
11. Save the text file in the same folder where you saved the private key, using the .pub extension to indicate that the file contains a public key.
12. If you or others are going to use an SSH client that requires the OpenSSH format for private keys (such as the ssh utility on Linux), export the private key:
    1. On the Conversions menu, choose Export OpenSSH key.
    2. Save the private key in OpenSSH format in the same folder where you saved the private key in .ppk format, using an extension such as .openssh to indicate the file's content.