PROJECT: Backup Tor Server

[shannona]

• Learn how to backup Tor server keys
• Make it easy to restore them

Lead: @nochiel

[nochiel]

Tor services/servers make use of ephemeral and persistent keys. For BlockckainCommons TorGap architecture, we are interested in keys used for identity/authentication.

Client authorization is a feature added with Tor v3. It uses public-key cryptography: a public key is stored on the server offering the hidden service, then a client connects with the corresponding private key. In order for the client to access the service, the keys must match.*

BlockckainCommons runs Tor infrastructure that require key management:

• Hidden services.
• Tor exit nodes.

There are 2 options for managing and backing up secrets/keys:

• A vault server e.g. HashiCorp's Vault
• A hosting service's secret management service e.g. Linode's Object Storage or AWS Secret Manager

In both cases, we would:

• Add secrets to the vault.
• Add access controls for each key.
• Create client access keys for each application that will programmatically use the vault.

Restoring keys when standing-up a hidden service or exit node is then a matter of securely accessing the vault using the Vault's API or cli-tool.

Key rotation and backup can also be similarly automated.