Blog post

Supabase Vault


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Today we're announcing Supabase Vault, a Postgres extension for managing secrets and encryption inside your database. Vault is a thin usability-layer on top of pgsodium.

Vault is not available on the Supabase platform yet. We're finalizing usability and security testing. This release is intended to gather user-feedback from our community and customers.

Soon, we'll release a blog post that describes more about the technology behind Vault - libsodium and pgsodium. For now, we will go through a quick example of storing a secret, like a service access token, into the Vault.


Until now, the industry-standard for PostgreSQL encryption is a built-in extension called pgcrypto. Like most cloud providers, Supabase offers pgcrypto for developers to use in their applications. pgcrypto has been around for a long time, and while it supports some basic encryption and decryption abilities, it lacks features like public key signing, key derivation APIs, streaming encryption, and other modern features required by security-first applications.

Problems with raw keys

Databases often store sensitive information, and they need tools that guarantee this data is stored and backed-up in an encrypted form. A fundamental issue with pgcrypto is that it lacks the ability to derive keys from outside of SQL. Instead you must have the raw encryption key for the algorithm you wish to use:

create extension pgcrypto;

create table users (
  id serial primary key,
  email varchar not null unique

insert into users
  (pgp_sym_encrypt('', 's3kr3t_k3y')),
  (pgp_sym_encrypt('', 's3kr3t_key'));

pgcrypto works with raw keys. In order to encrypt the data with pgcrypto you must pass the key directly to the encryption function. Leaking those raw keys is all too easy - logs, files, clients, tables, replication streams - you name it. Wouldn't it be great if you could encrypt data, but instead of specifying the raw key you reference it indirectly, like with a key ID?

Supabase Vault

Supabase Vault allows you to store secrets without leaking any sensitive information.

The Vault is a good place to put things like API keys, access tokens, and other secrets from external services that you need to access within your database. The core of the Supabase Vault is a table with some metadata and an encrypted text column where you can put your secrets and any metadata related to them.

We take the pain out of key management by pre-generating a unique, per-database key that is used by default - a “root” key - which is stored outside of the SQL language, accessibly only internally in the Postgres server by the libsodium library. This root key is managed by the pgsodium Postgres extension when the server boots using Server Key Management.

pgsodium provides an Encryption and Key Derivation API based on the libsodium library and can get it's root key from a variety of sources depending on how you configure it. Supabase generates and preserves your project's root key behind the scenes, so you don't have to worry about it. If you install pgsodium locally the default is to generate a random root key from the /dev/urandom device which is then saved in a file in your Postgres data directory.

Installing the vault extension is the same as any other Postgres extension:

create extension vault with schema vault;

Once enabled, you can insert secrets into the vault.secrets table:

insert into vault.secrets
  (secret, associated)
  ('s3kr3t_k3y', 'This is the secret API service key.');

Now when you look in the vault.secrets table, the secret is encrypted:

select * from vault.secrets;
-[ RECORD 1 ]--------------------------------------------------------
id         | f6a2fe0a-3471-4eea-a581-75c4d2be396b
secret     | /eT9bb96POTJ7L2gYrluTZ3r3pG5IMwPSQo6pQP0xdZTarpRrpWPXTWQ
key_id     | caabfc28-2ab3-48f5-8978-1b3d4b659911
associated | This is the secret API service key.
nonce      | \x77c7381c523630ba72f1f137626a9f9a
created_at | 2022-08-18 19:33:15.312651+00

Notice how the row has a key_id column. This is the ID of the internally derived key that is used to encrypt the secret, not the key itself. The actual raw key is not available to you in SQL, it is managed entirely outside of the SQL language in the Postgres server.

At Supabase, we manage this key for your project automatically and generate a unique default Key ID for you in the secrets table. For self-hosting, pgsodium supports a variety of ways to place the root key into Postgres.

To see the decrypted data, there is a special view created called vault.decrypted_secrets:

select * from vault.decrypted_secrets;
-[ RECORD 1 ]----+---------------------------------------------------------
id               | f6a2fe0a-3471-4eea-a581-75c4d2be396b
secret           | /eT9bb96POTJ7L2gYrluTZ3r3pG5IMwPSQo6pQP0xdZTarpRrpWPXTWQ
decrypted_secret | s3kr3t_k3y
key_id           | caabfc28-2ab3-48f5-8978-1b3d4b659911
associated       | This is the secret API service key.
nonce            | \x77c7381c523630ba72f1f137626a9f9a
created_at       | 2022-08-18 19:33:15.312651+00

Now you can see a new decrypted_secret column that contains the decrypted secret we originally inserted into the table. This vault.decrypted_secrets view automatically decrypts rows in the vault.secrets table “on-the-fly” as you query them, but the secret is stored on disk in encrypted form. If you take a backup, or pause your project, that data remains encrypted. We will keep your hidden root key safe in our backend systems for when you need to restore or un-pause your projects.

If you wish to use your own Key ID for different secrets, instead of the default Key ID we've generated, you can create one using the pgsodium.create_key() function:

select * from pgsodium.create_key('This is a comment for the new key');
-[ RECORD 1 ]-------------------------------------
id          | f9f176eb-7069-4743-9403-582c04354ffc
status      | valid
created     | 2022-08-18 22:31:50.331792
expires     |
key_type    | aead-det
key_id      | 2
key_context | \x7067736f6469756d
comment     | This is the comment for the new key
user_data   |

Now you can encrypt table secrets with this new key by inserting its ID explicitly:

insert into vault.secrets
  (secret, associated, key_id)
values (
  'This is some different associated data.',
returning *;
-[ RECORD 1 ]------------------------------------------------------------
id         | 9c58a0f3-aa40-4789-b683-6db48b241f9e
secret     | YWxuTnWdF55MuRrZ7xneBvaz2uH59U1dJV/7CCZjSn5B5jELOoy/csq8x/s=
key_id     | f9f176eb-7069-4743-9403-582c04354ffc
associated | This is some different associated data.
nonce      | \xd39808b07c9ae52c8f02c33a7f87595c
created_at | 2022-08-18 22:34:07.219941+00

The type of encryption used by the Vault is called Authenticated Encryption with Associated Data. The data you insert into the associated column, which is up to you, is combined with the encrypted text when libsodium creates the authentication signature for the secret. This means that when you read the secret, you know that the associated data is also authentic. The associated data could be an account ID or some information that ties your system to the secret. And as always, you can refer to rows in the secrets table by their primary key UUID.

If you only want to store secrets that you know are encrypted on disk and in backups, then all you need to know is shown above. Just insert secrets into the table, optionally creating new keys, and select them from the view when you want to use them.

Going Beyond the Vault

The Vault is good for a reasonable amount of secure data, like API keys, access tokens, or environment variables. But if you have a lot more sensitive information, like personally Identifiable Information (PII), you may want to break them out into side-tables using pgsodium's Transparent Column Encryption which we will describe soon in a follow-up blog post. Stay tuned!

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