Convert PuTTY Key to OpenSSH Key

Install PuTTYgen

If you don’t have putty-tools on Linux, install it at first.

# Install in Linux
sudo apt install putty-tools

If you use puttygen on Windows, install the PuTTYgen in the official page.

Generate Key Pair

# -t: key type
# -b: number of bits
# -C: key comment
# -o: output file
puttygen -t rsa -b 2084  -C "user@example.com" -o keyfile.ppk

PuTTY to SSH Key

If you use puttygen on Linux, run the following command to convert PuTTY key to OpenSSH keys (private/public).

# SSH private key
puttygen keyfile.ppk -O private-openssh -o id_rsa

# SSH public key
puttygen keyfile.ppk -O public-openssh -o id_rsa.pub

If you use puttygen on Windows, follow these steps:

1. Open PuTTYgen.
2. Click on Conversions → Import key at the top menu. Then upload the PuTTY key file (.ppk).
3. After uploading, click on Conversions → Export OpenSSH key.
4. The OpenSSH private key will be downloaded.