When examining an SSH public key (typically in ~/.ssh/id_rsa.pub), you'll notice it follows this format:

ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQ... user@example.com

The email address at the end is actually just a comment field that identifies the key's owner. This comment isn't cryptographically significant - it doesn't affect the key's functionality or security.

While you can't directly "edit" an existing keypair, here are three practical approaches:

Method 1: Change Comment When Copying Public Key

The simplest way is to recreate just the public key file with a new comment:

ssh-keygen -y -f ~/.ssh/id_rsa > ~/.ssh/id_rsa.pub.new
echo " new-email@example.com" >> ~/.ssh/id_rsa.pub.new
mv ~/.ssh/id_rsa.pub.new ~/.ssh/id_rsa.pub

Method 2: Fully Recreate Keypair With New Comment

For a complete refresh (keeping same private key):

cp ~/.ssh/id_rsa ~/.ssh/id_rsa.backup
ssh-keygen -c -C "new-email@example.com" -f ~/.ssh/id_rsa

Method 3: Using ssh-keygen Flags

Modern OpenSSH versions support direct comment modification:

ssh-keygen -f ~/.ssh/id_rsa -C "new-email@example.com"

• Always backup your original keys before modification
• Update authorized_keys files on servers where the key is deployed
• Modify git config if using the key with Git services
• The private key remains mathematically identical - only metadata changes

Check your new public key comment with:

ssh-keygen -l -f ~/.ssh/id_rsa.pub

Or inspect the file directly:

cat ~/.ssh/id_rsa.pub

---

When you generate an RSA keypair using ssh-keygen, it typically includes a comment field at the end of the public key. By default, this comment contains your username and hostname in the format user@hostname. Many users manually specify an email address instead using the -C flag during key generation:

ssh-keygen -t rsa -b 4096 -C "your_email@example.com"

No, the email address (or comment) in an SSH keypair is purely metadata. It's not cryptographically bound to the key material itself. This means:

• The comment can be changed without affecting the key's validity
• Changing it doesn't require generating new cryptographic material
• All existing authentications using the key will continue to work

There are two main approaches to update the email address in your SSH keypair:

Method 1: Update the Public Key Comment

You can directly edit the public key file (typically ~/.ssh/id_rsa.pub):

# Original public key
ssh-rsa AAAAB3NzaC1yc2E...SNIP... old_email@example.com

# Modified public key
ssh-rsa AAAAB3NzaC1yc2E...SNIP... new_email@example.com

Method 2: Recreate the Public Key with New Comment

If you prefer a cleaner approach, you can regenerate the public key from the private key with a new comment:

ssh-keygen -y -f ~/.ssh/id_rsa -C "new_email@example.com" > ~/.ssh/id_rsa.pub.new
mv ~/.ssh/id_rsa.pub.new ~/.ssh/id_rsa.pub

Before making changes:

• Backup your original key files
• Update any authorized_keys files on remote servers
• Notify services that use your public key (GitHub, GitLab, etc.)
• Consider whether a new keypair might be better for security rotation

While changing the email address is possible, consider generating a new keypair if:

• You suspect the private key might be compromised
• It's been several years since key generation
• You want to upgrade to a stronger algorithm (like ed25519)

# Generating a new keypair with updated email
ssh-keygen -t ed25519 -a 100 -C "new_email@example.com"