Transparent Data Encryption (TDE) v1
Important
TDE is available only for operands that support it: EPAS and PG Extended, versions 15 and newer.
Transparent Data Encryption, or TDE, is a technology used by several database vendors to encrypt data at rest, i.e. database files on disk. TDE does not however encrypt data in use.
TDE is included in EDB Postgres Advanced Server and EDB Postgres Extended Server from version 15, and is supported by the EDB Postgres for Kubernetes operator.
Important
Before you proceed, please take some time to familiarize with the TDE feature in the EPAS documentation.
With TDE activated, both WAL files and files for tables will be encrypted. Data encryption/decryption is entirely transparent to the user, as it is managed by the database without requiring any application changes or updated client drivers.
Note
In the code samples shown below, the epas
sub-section of postgresql
in
the YAML manifests is used to activate TDE. The epas
section can be used
to enable TDE for PG Extended images as well as for EPAS images.
EDB Postgres for Kubernetes provides 3 ways to use TDE:
- using a secret containing the passphrase
- using a secret containing a custom passphrase command
- using a pair of secrets containing custom wrap/unwrap commands
Passphrase secret
The basic approach is to store the passphrase in a Kubernetes secret. Such a passphrase will be used to encrypt the EPAS binary key.
EPAS documentation
Please refer to the EPAS documentation for details on the EPAS encryption key.
Activating TDE on the operator is simple. In the epas
section of the manifest,
use the tde
stanza to enable TDE, and set the Kubernetes secret that
will hold the TDE encryption key.
For example:
You can find an example in cluster-example-tde.yaml
.
Note
This file also contains the definition of the secret to hold the encryption key. Look at the following section for an example on how to create a secret for this purpose.
The key stored in the secret will be used as the pass-phrase to invoke
openssl
to wrap/unwrap the EPAS encryption key.
How to create the secret containing the passphrase
First choose the passphrase. While it is recommended to use a randomly
generated passphrase, in this example we will use PostgresRocks
as
passphrase, and rely on kubectl
to generate for us the secret definition:
This should return something like this:
Remember to run kubectl apply
or remove the -o yaml
option to the create
command above to actually create the secret in the cluster.
Custom passphrase command
Instead of the secretKeyRef
in the cluster manifest snippet above, it is
possible to specify a passphraseCommand
stored in a secret. The passphrase
command can be run to generate a passphrase to be used with openssl
.
The passphrase command should write to standard output.
For example, we could simply use echo my-passphrase
.
The passphrase generated by the command will be used the same way the
secretKeyRef was used, i.e. as a passphrase argument for openssl
.
Custom wrap/unwrap commands
It is also possible to specify the wrap and unwrap commands, rather than rely
on the default invocation of openssl
.
This can be done by creating secrets containing the custom commands, and
declaring those secrets in the tde
stanza.
The snippet below shows a cluster with TDE enabled using custom commands.
The custom commands need to obey the following conventions:
The custom wrap command should accept input from standard input, which EPAS will use to feed it the binary key. It should write to a file via an explicit argument (not shell redirections). Moreover, the file argument should be given the string "%p", which is a placeholder EPAS will use to pass the file path of the new, wrapped encryption key file.
The custom unwrap command should write to standard output. It should have an explicit file path argument for input (not shell redirections). Again, the file argument should be given the string "%p", which is the placeholder EPAS will fill in with the wrapped encryption key file path.
For example:
- wrap command:
openssl enc -aes-128-cbc -pass pass:temp-pass -e -out %p
- unwrap command:
openssl enc -aes-128-cbc -pass pass:temp-pass -d -in %p
Example using HashiCorp Vault
The following example shows how to use HashiCorp Vault to store the encryption
key and use it to activate TDE. The vault
CLI is used to interact with Vault
and is included by default in the EDB Postgres Advanced Server (EPAS) image.
First, wherever you have vault running you must enable the Transit secrets engine and create a key:
Then, create a secret containing the custom wrap/unwrap commands. The wrap and unwrap commands will 'wrap' a binary that is in the EPAS image. The binary will interact with the vault API to encrypt/decrypt the EPAS encryption.
The binary needs 4 flags: --host
, --secret
, --key
and --vault-endpoint
. The
--host
flag is in the format of http://vault-host:vault-port
and needs to be
provided to reach the Vault. The server--secret
flag is the name of the Kubernetes
secret that contains the vault token and the --key
flag is the key in that secret
pointing the vault token. The --vault-endpoint
flag is the name of the key that
was created inside vault; in the example above it is pg-tde
.
If running the Vault operator in Kubernetes the root token can be obtained from the following two commands:
You can now create a Cluster that is referencing the secrets: