This guide describes how to set up SSH key-based authentication to a Raspberry Pi using Windows PowerShell.

1. Generate an SSH Key Pair

Open Windows PowerShell and run:

ssh-keygen -t ed25519 -C "your_email@example.com"

Press Enter to accept the default path (C:\Users\YourName.ssh\id_ed25519).

Optionally enter a passphrase for extra security.

Display the public key to copy it:

type $env:USERPROFILE\.ssh\id_ed25519.pub

Copy the entire output line. It should start with ssh-ed25519.

2. Login to Linux Host normally

Create the .ssh Directory on the Pi

mkdir -p ~/.ssh
chmod 700 ~/.ssh

3. Create or edit authorized_keys File

Open the file

nano ~/.ssh/authorized_keys

In the editor, paste the entire public key

4. Set correct permissions

chmod 600 ~/.ssh/authorized_keys

Confirm configuration:

sudo nano /etc/ssh/sshd_config

Ensure the following lines are set:

PubkeyAuthentication yes
AuthorizedKeysFile .ssh/authorized_keys
PasswordAuthentication yes

sudo systemctl restart ssh

5. Test SSH Key Authentication

ssh username@<ip_address>

It should connect without a password prompt

6. (Optional) Disable Password Authentication

After confirming key-based login works, you can improve security by disabling password login:

sudo nano /etc/ssh/sshd_config

set:

PasswordAuthentication no

Restart SSH

sudo systemctl restart ssh

Notes

If key authentication fails, test with verbose output:

ssh -vvv username@<ip_address>

Ensure correct permissions on the Pi:

~/.ssh directory: 700
~/.ssh/authorized_keys: 600

Do not delete your private key (id_ed25519) on your Windows machine.