HashiCorp Certified: Consul Associate Certification

Use Gossip Encryption

Manage the Lifecycle of Encryption Keys

In this lesson we’ll demonstrate how to use Consul’s gossip encryption keyring to list, distribute, activate, and retire encryption keys—enabling you to enforce regular rotations (e.g., every six months or annually) without downtime. Many security policies mandate periodic key rotations to maintain compliance and minimize risk. Consul’s built-in consul keyring and consul keygen commands provide a straightforward day-two workflow for these tasks.

The image provides instructions on managing encryption keys using "consul keyring" and "consul keygen," highlighting key management tasks and recommendations.

Why Rotate Gossip Encryption Keys?

  • Ensures forward secrecy and mitigates the impact of key compromise
  • Aligns with security best practices and compliance requirements (e.g., PCI-DSS, HIPAA)
  • Operates transparently, maintaining cluster availability during rotation

Note

Consul’s gossip encryption uses a 32-byte Base64 key. You can generate this key with any tool, but consul keygen guarantees compatibility.

1. Generate a New Key

Leverage the built-in key generator to produce a 32-byte Base64 string:

consul keygen

Example output:

VCjCNv+521LNTBcQcdu8rl9pjTHEuw+dhzf2bvici3w=

2. Consul Keyring Commands

Use consul keyring to manage keys across your Consul agents. The four primary subcommands are:

CommandDescription
consul keyring listList all installed gossip encryption keys
consul keyring install <key>Distribute a new key to every Consul agent
consul keyring use <key>Set a specific key as the primary encryption key
consul keyring remove <key>Retire a no-longer-used key from the cluster

Warning

Avoid running with multiple active keys longer than necessary. Each Consul agent will attempt decryption with every key on inbound messages, increasing CPU overhead.

3. Example Rotation Workflow

Follow these steps to rotate keys seamlessly:

# 1. List existing keys
consul keyring list
# ==> Gathering installed encryption keys...
# dc1 (LAN):
# 2. Install the newly generated key
consul keyring install VCjCNv+521LNTBcQcdu8rl9pjTHEuw+dhzf2bvici3w=
# 3. Activate the new key
consul keyring use VCjCNv+521LNTBcQcdu8rl9pjTHEuw+dhzf2bvici3w=
# 4. Remove the old key (optional once no longer used)
consul keyring remove hDqYxqQepkYyRADn4Zn+u+D9vLgE8WM+LpFAPLGhtco=
# ==> Removing gossip encryption key...

If you attempt to remove a key that’s still active, Consul will refuse and require you to switch primary keys first.

4. Rotation Workflow Cheat Sheet

StepCommand
Generate keyconsul keygen
Distribute keyconsul keyring install <new_key>
Activate keyconsul keyring use <new_key>
Retire keyconsul keyring remove <old_key>

This process incurs zero downtime for Consul servers and clients. Automate these commands via scripts or integrate into your CI/CD pipeline to enforce more frequent rotations (daily, weekly, or monthly).


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