Publishing Your Public Keys

Why Publishing Your Public Key Matters

After creating your PGP keys, the next crucial step is to make your public key readily available to others. Remember, the whole purpose of public key cryptography is that people need your public key to:

• Send you encrypted messages that only you can read
• Verify the authenticity of messages you've digitally signed

If your contacts can't easily find your public key, they simply can't communicate securely with you. It's like having a secure mailbox but not telling anyone your address!

Preparing Your Public Key for Distribution

Before publishing your key, let's ensure it's in the right format for easy sharing.

Exporting Your Public Key

In Secure Mail Client, you can export your public key by:

1. Navigate to Key Management in the main menu
2. Select your key from the list
3. Click Export Public Key
4. Choose ASCII Armored format (this is a text-based format ideal for sharing)
5. Save the file with a .asc extension (e.g., yourname_public_key.asc)

For command-line users, you can export your public key with:

      
        
# Replace [email protected] with your actual email
gpg --armor --export [email protected] > yourname_public_key.asc

      
    

The resulting file contains your public key in a text format that begins with -----BEGIN PGP PUBLIC KEY BLOCK----- and ends with -----END PGP PUBLIC KEY BLOCK-----.

Know Your Key Information

Before publishing, make sure you know your key's identifiers:

• Key ID: A short identifier (e.g., A1B2C3D4)
• Fingerprint: A longer, more secure identifier (e.g., 1234 5678 90AB CDEF 1234 5678 90AB CDEF 1234 5678)
• Associated Email: The email address(es) connected to your key

In Secure Mail Client, this information is displayed in the Key Details view. For command-line users:

      
        
# List keys with fingerprints
gpg --fingerprint [email protected]

      
    

Methods for Publishing Your Public Key

There are several ways to make your public key available to others. Using multiple methods increases the chances that your contacts will find your key when they need it.

1. Publishing to Public Key Servers

Key servers are specialized directories that store and distribute PGP public keys. They allow anyone to search for keys by email address or key ID.

Using Secure Mail Client to Publish Your Key

Secure Mail Client provides a simple interface for key server publication:

1. Navigate to Key Management
2. Select your key
3. Click Publish to Key Server
4. Select the desired key server (or use the default)
5. Click Publish

Using Command-Line Tools

For command-line users, you can publish your key with:

      
        
# Using keys.openpgp.org (recommended)
gpg --keyserver keys.openpgp.org --send-keys YOUR_KEY_ID

# Or using keyserver.ubuntu.com
gpg --keyserver keyserver.ubuntu.com --send-keys YOUR_KEY_ID

# Replace YOUR_KEY_ID with your actual key ID

      
    

Verifying Key Publication

After publishing, verify that your key was successfully uploaded by searching for it:

      
        
# Search by email
gpg --keyserver keys.openpgp.org --search-keys [email protected]

# Or search by key ID
gpg --keyserver keys.openpgp.org --search-keys YOUR_KEY_ID

      
    

Some key servers like keys.openpgp.org will send you a verification email. You must click the verification link in this email to fully publish your key with your email address.

2. Sharing Your Public Key Directly

While key servers are convenient, direct sharing ensures your recipient gets exactly the right key.

Email Attachment

The simplest approach is to attach your public key file to an email:

1. Compose a new email to your contact
2. Attach your exported public key file (yourname_public_key.asc)
3. Include a brief explanation in the email body

Email Signature

Including your public key in your email signature makes it available with every message you send:

1. Configure your email client to include your public key as an attachment to your signature
2. Or include a link to where your key can be downloaded

3. Publishing on Your Website or Social Media

If you have a personal website, blog, or active social media profiles, these are excellent places to publish your public key.

Website Publication

On your website:

1. Create a dedicated page or section for your public key
2. Include both a downloadable file and the key text directly on the page
3. Add your key fingerprint for verification

For advanced users, consider using the standard location:

      
        
https://yourwebsite.com/.well-known/openpgpkey/hu/[hash]

      
    

This follows the OpenPGP Web Key Directory standard, which allows automatic discovery of keys.

Social Media Profiles

For social media:

• Include your key fingerprint in your bio or profile
• Add a link to where your full key can be downloaded
• For platforms with fixed profile fields, include this information in your bio

Verifying and Helping Others Find Your Key

Creating a Key Discovery Strategy

To maximize the chances of others finding your key when they need it:

1. Use multiple publication methods (key servers, website, email)
2. Always include your key fingerprint when referencing your key
3. Keep the information consistent across all platforms
4. Update all locations if you generate a new key

Testing Your Key Discovery

Before relying on your published key, test the discovery process:

1. Use a different device or ask a friend to try finding your key
2. Try searching by email address and by key ID
3. Verify that the fingerprint matches your expected key
4. Test importing the key into PGP software

Using Secure Mail Client's Key Publication Features

Secure Mail Client simplifies the key management process with built-in features:

To access these features in Secure Mail Client:

1. Navigate to Key Management in the main menu
2. Select your key
3. Click Distribution Options to see all available sharing methods

Storing the Public Key URL on YubiKey

If you're using a YubiKey for your PGP keys, you can store a URL pointing to your public key directly on the YubiKey itself. This creates a self-referencing system where anyone with your YubiKey can find your public key.

Why Store the URL on Your YubiKey?

• Automated retrieval: Some PGP software can automatically fetch your public key using this URL
• Seamless key rotation: When you update your key, just update the hosted key at the same URL
• Simplified sharing: In person verification becomes easier when the key location is built into the device
• Reduced user error: Eliminates the problem of using incorrect or outdated keys

Setting the URL Field on Your YubiKey

In Secure Mail Client, you can configure this feature through the YubiKey Management interface:

1. Go to Key Management > YubiKey Settings
2. Select Edit OpenPGP Application
3. Navigate to the URL Settings tab
4. Enter the URL where your public key can be accessed
5. Save the changes to your YubiKey

For command-line users, you can set the URL using GnuPG:

      
        
# Connect to your YubiKey
gpg --card-edit

# Inside the card editor, use the "url" command
gpg/card> admin
Admin commands are allowed

gpg/card> url
URL to retrieve public key: https://example.com/pubkey.asc

# Review the changes
gpg/card> list

# Save and exit
gpg/card> quit

      
    

How Key Verification Works with YubiKey URLs

When you store a URL on your YubiKey, you're creating a powerful verification mechanism:

When using this feature, always verify that the URL is accessible and returns the correct key before relying on it.

When to Update Your Published Keys

Your published keys should be kept up-to-date. Republish your public key when:

• You've extended the key's expiration date
• You've added or revoked subkeys
• You've added new user IDs (email addresses) to your key
• You've gained new certifications (signatures) from other users
• You've created an entirely new key and are transitioning to it

The process for updating is generally the same as the initial publication—send the updated key to key servers and update any directly shared copies. If you're using the YubiKey URL feature, make sure to update the key at the referenced URL.

Summary and Next Steps

Publishing your public key is an essential step in using PGP encryption effectively. By making your key easily discoverable through multiple channels, you ensure that others can communicate securely with you whenever needed.

• Use key servers for broad availability
• Share directly with important contacts
• Include your key or a link to it in your online profiles
• Verify that others can find and access your key
• Keep your published keys updated