How to See the ed25519 SSH Key Format Before Generating One

Setting up SSH access for the first time, or double-checking that a public key file looks right, means knowing exactly what a properly formatted ed25519 SSH public key is supposed to look like — the algorithm prefix, the base64-encoded key data, and the optional comment at the end. Actually generating a real, usable SSH key pair should always happen locally on your own machine through the standard ssh-keygen command, never through a web tool, since a private key genuinely needs to never leave your device.

Understanding the format first — what a real public key file looks like, field by field — makes it much easier to verify you’ve generated and configured things correctly once you run the real command yourself.

What an ed25519 SSH public key actually looks like

An ed25519 SSH public key file follows a consistent, three-part format: the algorithm identifier (ssh-ed25519), the base64-encoded public key data itself, and an optional trailing comment (often an email or a descriptive label) that helps identify which key is which when you have several. Ed25519 is a modern elliptic-curve algorithm, generally preferred over older RSA keys for being both more secure at a shorter key length and faster for cryptographic operations.

Critically, only the public key is meant to be shared — placed in a server’s authorized_keys file or given to a service like GitHub — while the corresponding private key must stay exclusively on your own machine, never transmitted anywhere, which is exactly why the actual key generation needs to happen locally via ssh-keygen, not through any web-based tool.

Why people get stuck here

• Public and private key roles get confused, especially by newcomers. Understanding that only the public key is meant to be shared, while the private key must never leave your machine, is a foundational distinction that’s easy to get backward when first setting up SSH access.
• The exact three-part public key format isn’t always obvious from documentation alone. Seeing what a correctly formatted key actually looks like, field by field, makes it much easier to verify your own generated key matches the expected structure.
• Some people are tempted to use a web tool to generate SSH keys, which is a real security risk. Any tool that generates a private key server-side, rather than purely locally on your own machine, introduces a risk the private key could be exposed or logged somewhere it shouldn’t be.
• RSA versus ed25519 tradeoffs aren’t always well understood. Not knowing why ed25519 is generally the modern recommendation over older RSA keys can lead to defaulting to an older, less optimal algorithm out of familiarity alone.

What a good SSH key format reference looks like

Shows the exact structure without generating a real key

Displaying what a correctly formatted public key looks like — algorithm prefix, encoded data, optional comment — without ever touching an actual private key, keeps the reference genuinely safe to use.

Provides the real terminal command to run locally

Giving you the exact ssh-keygen command to actually generate a usable key pair on your own machine is the appropriate next step after understanding the format, rather than attempting generation through the web tool itself.

Is explicit that private keys should never be generated or handled outside your own machine

Being clear about this boundary reinforces the correct security practice rather than implying a web tool could safely handle real key generation.

Common mistakes to avoid

• Generating an SSH key pair through a web-based tool instead of locally via ssh-keygen, risking private key exposure.
• Confusing which key (public or private) is meant to be shared, and accidentally distributing a private key.
• Not recognizing the standard three-part public key format, making it harder to verify your own generated key is correctly structured.
• Defaulting to an older RSA key out of familiarity without understanding why ed25519 is generally the modern recommendation.

How to do it with SSH Key Generator

Online Tool Store’s SSH Key Generator shows exactly what an ed25519 SSH public key file looks like, then gives you the terminal command to generate a real key pair locally — nothing here touches an actual private key.

1. Review the exact ed25519 public key format shown.
2. Get the real ssh-keygen terminal command.
3. Run that command locally on your own machine to generate your actual key pair.
4. Share only the resulting public key — never the private key.

Because it only shows the format and the real command to run locally, without generating or handling any actual private key itself, you get a safe reference without any of the risk a web-based key generation tool would introduce.

Frequently asked questions

Why shouldn’t I generate an actual SSH key pair through a web tool?

A private key needs to stay exclusively on your own machine and never be transmitted anywhere — any tool that generates one server-side introduces a real risk that the private key could be exposed, logged, or intercepted somewhere it shouldn’t be.

Why is ed25519 generally recommended over RSA?

Ed25519 is a modern elliptic-curve algorithm that’s both more secure at a shorter key length and faster for cryptographic operations compared to older RSA keys, which is why it’s generally the current recommendation for new SSH key generation.

What’s actually safe to share — the public key or the private key?

Only the public key is meant to be shared, placed in places like a server’s authorized_keys file or a service like GitHub. The private key must never be shared or transmitted anywhere and should stay exclusively on the machine where it was generated.

Final thought

Understanding the exact ed25519 public key format makes it easier to verify your own setup once you generate a real key pair locally — and real key generation should always happen through ssh-keygen on your own machine, never through a web tool. See the format here, generate the real thing locally.

Try the free SSH Key Generator