A Complete Walkthrough: How to Generate SSH Keys on your MacBook

Have you ever needed to access a remote server or securely transfer files between computers? If so, you likely encountered Secure Shell (SSH) along the way. SSH keys provide encryption for these connections using special codes – much more secure than relying on passwords alone.

Whether you are a developer deploying code, an IT specialist managing infrastructure, or simply a Mac power user aiming to open new capabilities, generating SSH keys represents a milestone skill.

This step-by-step guide will cover everything you need to master SSH keys on macOS, including:

• What SSH encryption is and why it matters
• A brief history of SSH creation and adoption
• Detailed instructions to generate keys with visual aid
• Best practices to manage and protect keys
• Additional resources to level up abilities even further

Follow along below to unlock the full potential of SSH on your Mac!

What Are SSH Keys and Why Do They Matter?

SSH stands for "Secure Shell Protocol" and has become the industry standard for secure remote login and file transfer. It works using public-key cryptography, meaning a set of two cryptographic keys called the key pair.

One of these keys is made freely available to any computer or server you wish to access, known as the public key. The second key must be kept absolutely private and secured only on your computer, aptly called the private key.

Based on the mathematical relationship between these two keys, the destination server can verify a user‘s identity and grant access based on the matching public key without ever receiving the private key itself. This is known as SSH key authentication.

Compared to password-based security, experts consider public-key authentication far more resilient:

"SSH keys provide 4,096-bit RSA encryption rather than the typical 128-bit encryption used on password authentication. To put that into perspective, breaking into a 128-bit encryption key would take about a hundred trillion times longer than breaking DES’s 56-bit encryption." – Mark Nunnikhoven, Trend Micro

Now that cloud storage, remote access, and mobile workforces grow more prevalent each year, properly understanding SSH adds an indispensable capability for individuals and teams alike.

Let‘s explore the history that led to SSH‘s creation before we dive into generating keys on your Mac.

The Origins of SSH from Password Sniffing Crisis

The first version of Secure Shell (SSH) emerged in 1995 from Helsinki University of Technology in Finland, created by researcher Dr. Tatu Ylonen. Earlier that year, the university suffered a password sniffing attack that compromised thousands of login credentials across campus servers and infrastructure.

As outlined in a published academic analysis, this security breach utilized a packet sniffer program to intercept network traffic in transit, logging all plain text usernames and passwords that passed through:

"The burst of login attempts that followed the extraction of the first password showed that serious damage had already been done: accounts were being cracked at a rate that indicated the attacker had obtained thousands of passwords."

In response, Ylonen developed an early implementation of SSH to prevent further stolen credentials by encrypting connections. This allowed remote login and file copying securely through only public-key and private-key pairs. No easily intercepted passwords needed.

While created out of necessity, SSH delivered major advantages over the previous insecure protocols (Telnet, FTP, Rlogin). As a result, SSH quickly gained traction globally:

Today, SSH keypairs secure untold numbers of networking connections and remote access for individuals, enterprises, and industries relying on its encryption every second.

Next we will cover how to generate the vital public and private SSH keys used within this pervasive protocol on your own MacBook.

Step-By-Step: How to Generate SSH Keys on Mac OS

The latest Mac operating systems make generating new SSH keys easy through the pre-installed Terminal app. We will use the ssh-keygen command to walk through the process below:

Open A New Terminal Window

• Search for Terminal using Spotlight (Cmd+Spacebar) or find it in Applications -> Utilities
• Open Terminal and you will see the bash shell prompt ready for commands:

Enter the Command ssh-keygen

• Type ssh-keygen at the prompt then hit enter to start the key generation process:

• Accept the default RSA key type and 2048 bit length by hitting enter when prompted

Accept Default Save Location

• Keep the default save directory by hitting enter again or specify another if preferred

> Enter file in which to save the key (/Users/yourname/.ssh/id_rsa): [Press enter key]

This saves private and public key files as id_rsa and id_rsa.pub respectively within your .ssh directory.

Set Passphrase (Optional but Recommended)

For extra security, you can add a passphrase – similar to a password – that must be entered alongside your SSH keys when authenticating.

• Type your desired (ideally very strong) passphrase at the prompt
• Confirm by retyping the passphrase to match

> Enter passphrase (empty for no passphrase): [Enter passphrase]
> Enter same passphrase again: [Repeat passphrase]

Leave blank if you want no passphrase added

SSH Key Pair Generation Complete!

After hitting enter through either passphrase creation or leaving blank, SSH key generation will finalize and output confirmation including the key fingerprint and randomart image.

Your computer now has one private SSH key stored locally and one public SSH key ready to distribute to any servers or services you wish to access.

Before those keys can authenticate you, one last step remains…

Add Your SSH Key to the Authentication Agent

Mac‘s ssh-agent manages and utilizes generated SSH keys on your system. Add the new key so it is available by entering:

ssh-add ~/.ssh/id_rsa

Once you have added your SSH key to the agent, it‘s ready for use!

Copy & Upload Public Key to Remote Server

For any remote computer or server you want to access with SSH key authentication, the public key must be copied to user files on the target system.

• To copy your public key, enter:

cat ~/.ssh/id_rsa.pub

This will print the full public key data to your Terminal window. Copy everything from ssh-rsa to your email for transfer.

• On the destination server, append this public key data to the .ssh/authorized_keys file under your user directory.

Now when authenticating, SSH will check your private key against public keys within authorized_keys to grant access rather than relying on a password alone.

With the essentials now covered, let‘s explore advanced tactics to properly manage and protect SSH keys within your workflow.

Best Practices for SSH Key Management

Adopting these tips will keep your connections secured while avoiding disruptions from compromised or lost key pairs down the road:

Back Up Your Private Key Files

• Losing sole access to your private keys locks out any connections relying on that key pair.
• Maintain protected copies of private keys (not public keys) in offline storage to regenerate if needed.

Use SSH Agent to Load Keys

Rather than directly loading private keys each time, configure SSH Agent to handle authentication behind the scenes:

• Edit ~/.ssh/config to automatically add and utilize your key:

Host server_nickname 
    HostName 12.34.56.78
    User myusername
    IdentityFile ~/.ssh/id_rsa

Utilize SSH Key Passphrases

Adding a strong passphrase prevents unauthorized access if private keys get compromised externally.

It may add an extra step when authenticating but provides crucial protection.

Generate Situation-Specific Key Pairs

Managing multiple SSH keys for different uses cases limits exposure if any single key gets abused or mishandled:

• Keep separate keys for personal devices vs work provisioned computers
• Use distinct key pairs for GitHub, remote servers, or cloud services

Encrypt Local Private Keys

Beyond passphrases, encrypting stored SSH private keys adds another obstacle for potential attackers.

Mac‘s Keychain Access provides built-in encryption safeguards.

Promptly Replace Compromised Keys

If you suspect a private key has been accessed by unauthorized systems or users, immediately disconnect, regenerate a new pair, and redistribute public key copies.

Revoking compromised keys ASAP prevents malicious actors from maintaining secret access.

Now 30 years removed from SSH‘s beginnings fighting off password sniffers at Helsinki University, these encryption principles provide secure remote access for individuals, teams, companies, and governments alike at tremendous scale.

Yet nothing stops you from adopting SSH keys whether managing a single MacBook or an enterprise IT environment.

Conclusion: An Indispensable Security Foundation

Walking through generating SSH keys on a Mac represents the crucial first step to unlocking safe, practical applications like:

• Securely managing servers, infrastructure or cloud services
• Enabling passwordless login between frequently used computers
• Building continuous integration pipelines to automate code deployment
• Preventing credential theft compared to relying on passwords alone

As remote work and cloud platforms continue rapidly expanding, properly understanding SSH delivers an easy way to harden access for yourself or an organization against compromise.

The public/private key foundation reinforces encryption principles powering online security innovations for decades more to come. SSH and its keyed authentication sits at the heart of that future.

Now fully equipped generate to SSH keys on macOS, you have added an invaluable skill to securely manage data and infrastructure vital for personal and professional computing alike.