Vault

Managing secrets in Postgres.

Vault is a Postgres extension and accompanying Supabase UI that makes it safe and easy to store encrypted secrets and other data in your database. This opens up a lot of possibilities to use Postgres in ways that go beyond what is available in a stock distribution.

Under the hood, the Vault is a table of Secrets and Encryption Keys that are stored using Authenticated Encryption on disk. They are then available in decrypted form through a Postgres view so that the secrets can be used by applications from SQL. Because the secrets are stored on disk encrypted and authenticated, any backups or replication streams also preserve this encryption in a way that can't be decrypted or forged.

Supabase provides a dashboard UI for the Vault that makes storing secrets easy. Click a button, type in your secret, and save. Optionally create your own keys you can use to encrypt your secret. Your secret will then be stored on disk encrypted using the specified key.

There are two main parts to the Vault UI, Secrets and Encryption Keys:

Secrets#

You can use the Vault to store secrets - everything from Environment Variables to API Keys. You can then use these secrets anywhere in your database: Postgres Functions, Triggers, and Webhooks. From a SQL perspective, accessing secrets is as easy as querying a table (or in this case, a view). The underlying secrets tables will be stored in encrypted form.

Encryption keys#

These are keys used to encrypt data inside your database. You can create different Encryption Keys for different purposes, for example: one for encrypting user-data, and another for application-data. Each key is encrypted itself using a root encryption key that lives outside of the database. See Encryption key location for more details.

Using the Vault#

You can manage secrets and encryption keys from the UI or using SQL.

Adding secrets#

There is also a handy function for creating secrets called vault.create_secret():

The function returns the UUID of the new secret.

Secrets can also have an optional unique name and an optional description. These are also arguments to vault.create_secret():

Alternatively, you can create a secret by inserting data into the vault.secret table:

Viewing secrets#

If you look in the vault.secrets table, you will see that your data is stored encrypted. To decrypt the data, there is an automatically created view vault.decrypted_secrets. This view will decrypt secret data on the fly:

Notice how this view has a decrypted_secret column that contains the decrypted secrets. Views are not stored on disk, they are only run at query time, so the secret remains encrypted on disk, and in any backup dumps or replication streams.

You should ensure that you protect access to this view with the appropriate SQL privilege settings at all times, as anyone that has access to the view has access to decrypted secrets.

Updating secrets#

A secret can be updated with the vault.update_secret() function, this function makes updating secrets easy, just provide the secret UUID as the first argument, and then an updated secret, updated optional unique name, or updated description:

Deep dive#

As we mentioned, the Vault uses pgsodium's Transparent Column Encryption (TCE) to store secrets in an authenticated encrypted form. There are some details around that you may be curious about, what does authenticated mean, and where are encryption keys store? This section explains those details.

Authenticated encryption with associated data#

The first important feature of TCE is that it uses an Authenticated Encryption with Associated Data encryption algorithm (based on libsodium).

Encryption key location#

Authenticated Encryption means that in addition to the data being encrypted, it is also signed so that it cannot be forged. You can guarantee that the data was encrypted by someone you trust, which you wouldn't get with encryption alone. The decryption function verifies that the signature is valid before decrypting the value.

Associated Data means that you can include any other columns from the same row as part of the signature computation. This doesn't encrypt those other columns - rather it ensures that your encrypted value is only associated with columns from that row. If an attacker were to copy an encrypted value from another row to the current one, the signature would be rejected (assuming you used a unique column in the associated data).

Another important feature of pgsodium is that the encryption keys are never stored in the database alongside the encrypted data. Instead, only a Key ID is stored, which is a reference to the key that is only accessible outside of SQL. Even if an attacker can capture a dump of your entire database, they will see only encrypted data and key IDs, never the raw key itself.

This is an important safety precaution - there is little value in storing the encryption key in the database itself as this would be like locking your front door but leaving the key in the lock! Storing the key outside the database fixes this issue.

Where are the keys stored? Supabase creates and manages the root keys (from which all key IDs are derived) in our secured backend systems. We keep this root key safe and separate from your data. You remain in control of your keys - a separate API endpoint is available that you can use to access the key if you want to decrypt your data outside of Supabase.

Internal details#

To encrypt data, you need a key id. You can use the default key id created automatically for every project, or create your own key ids Using the pgsodium.create_key() function. Key ids are used to internally derive the encryption key used to encrypt secrets in the vault. Vault users typically do not have access to the key itself, only the key id.

Both vault.create_secret() and vault.update_secret() take an optional fourth new_key_id argument. This argument can be used to store a different key id for the secret instead of the default value.

Result:

Which roles should have access to the vault.secrets table should be carefully considered. There are two ways to grant access, the first is that the postgres user can explicitly grant access to the vault table itself.

Resources#

• Read more about Supabase Vault in the blog post
• Supabase Vault on GitHub
• Column Encryption