How to Import Ed25519 Keys for Use in PuTTY on Windows (Plus Native Windows OpenSSH)

Original Archive (November 2019) + 2026 AI Modernization: Preserves the original PuTTYgen .ppk key conversion walkthrough and adds modern native Windows OpenSSH and hardware-backed ed25519-sk workflows.

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Original Guide (November 2019): Importing Ed25519 Keys into PuTTY

Go to your SSH key directory and print the contents of the private key file (id_ed25519 in my case):

Create a new text file and paste the contents of your private key file inside and save:

Open PuTTY Key Generator (PuTTYgen):

1. Click File → Load private key
2. Select All Files (*.*) from file extensions
3. Open the text file containing your key

The key is imported now:

Now, you can save your private key in PuTTY’s .ppk format. Click on Save private key:

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2026 Modernization & Best Practices

1. Use Native OpenSSH in Windows 10/11 & Windows Terminal (No .ppk Conversion Needed!)

Modern Windows 10, Windows 11, and Windows Server 2019–2025 ship with a native OpenSSH Client pre-installed. You can use standard id_ed25519 keys directly from Windows Terminal or PowerShell without converting them to .ppk:

# 1. Place your key in your Windows user profile .ssh folder:
# C:\Users\<YourUsername>\.ssh\id_ed25519

# 2. Enable the native Windows OpenSSH Authentication Agent service
Get-Service ssh-agent | Set-Service -StartupType Automatic
Start-Service ssh-agent

# 3. Add your Ed25519 key to the Windows SSH Agent
ssh-add "$env:USERPROFILE\.ssh\id_ed25519"

# 4. Connect directly from PowerShell / Windows Terminal!
ssh andre@192.168.1.50

2. Security Note if You Still Use PuTTY

• Delete Temporary Key Copies: If you copy a private key across machines to import into PuTTYgen, ensure you securely delete the intermediate .txt file afterward so an unencrypted copy isn’t left on disk or indexed by cloud sync tools.
• Use PPK v3: Always use PuTTY 0.75+ (latest in 2026 is 0.81+), which uses the PPK v3 file format with Argon2 key derivation to protect passphrases against brute-force attacks.