Encrypting log messages

This tutorial walks you through how to encrypt log messages that are generated by your container workload in your IBM Hyper Protect Virtual Server instance.


Every IBM Hyper Protect Virtual Server instance is created with a valid contract. One section of the contract stores your logging configuration. The logs produced by your deployed workload are sent via TLS to your designated logging service and are later displayed on the logging dashboard.

If your workload produces sensitive information, you can take similar steps as in this tutorial to make selected log messages display as ciphertext on the logging dashboard. To retrieve the deciphered messages, you can download the logs from your Log Analysis instance and decrypt them locally.

In this tutorial, we use Log Analysis as the logging service. The process also applies to a syslog server.


This tutorial deploys a Docker container as a Hyper Protect Virtual Server. Inside the /example-files folder, you can find the following materials:

  1. A docker-compose.yaml file under the /compose directory, which deploys and manages the container application to be used in this tutorial. The image that we use is the official Ubuntu image from DockerHub.
  2. Within the Docker Compose file, there is a command: instruction to tell Docker to run a Shell script that prints a line of plain text, and a line of encrypted message to the standard output. This example.sh file exists in the /compose/bin directory.
  3. A public key logging.pub is required for encrypting the log message. This file must exist in the /compose folder. This tutorial will show an example of generating a key pair encrypted via AES with a passphrase using openssl.
  4. The volumes: instruction tells Docker to mount the compose volume with the public key and the simple logging application to /var/logging inside the container. The Ubuntu image will start as a container later and run example.sh as its main application.

The contract is a YAML file to specify the Hyper Protect Virtual Server instance that you want to create. In this tutorial, a dedicated public and private key pair is used to encrypt and decrypt the selected log messages.

  • The private key is kept by you to decrypt the downloaded logs later.
  • The public key must be embedded into the contract, which is a special approach for our case. The public key logging.pub is stored under the /example-files folder along with the docker-compose.yml file. As mentioned in the preparation of the workload section of the contract, the archive subsection contains the base64 encoded TGZ file archive of docker-compose.yml. The logging.pub file in our example will undergo the same encoding and compression since it's stored in the same folder. As a result, the created instance will acquire the public key for subsequent log encryption.

This tutorial also provides sample files such as env.yaml, workload.yaml, and user-data.yaml. They are only meant as references for correct schema.

Before you begin

  1. Install OpenSSL for encryption. This tutorial uses version 3.0 or later.
  2. Set up your logging instance by following the documentation.
  3. Read the system requirements. The following example is tested on an IBM z16 logical partition (LPAR) with secure execution enabled as the Kernel-based Virtual Machine (KVM) host.

Prepare your contract

This tutorial will get you started with a simple Hyper Protect Virtual Server contract that only has an env section and a workload section.

As recommended in the documentation, we will encrypt both sections. When the instance boots, the bootloader decrypts the contract if it's encrypted. Download the certificate to be used to encrypt the contract by following the instructions in Downloading the IBM Hyper Protect Container Runtime image. Follow the steps there to extract the *.gz file. Look for the certificate under the config/certs directory. By the time this tutorial is designed, the certificate is ibm-hyper-protect-container-runtime-23.3.0-encrypt.crt. You might see a different version number. The file hpcr.crt is already available inside /example-files. This will serve the purpose of encrypting the contract. Follow the steps to obtain the simple contract:

  1. Get the hostname and the ingestion key of your Log Analysis instance. See Logging for IBM Hyper Protect Virtual Servers.

  2. Create and encrypt the env section. Refer to the env.yaml file in the example-files folder for the correct schema. Replace the content with your logging hostname and ingestion key. Run the encrypt-basic.sh script to obtain the encrypted env section of the contract.

    cat env.yaml | ./encrypt-basic.sh hpcr.crt
  3. Create the workload section. Refer to the workload.yaml sample file in the example-files folder for the correct schema. In this example, the docker compose file in the example-files folder will be used for the compose subsection.

    In addition, provide the public key for encrypting the log messages. Run the following commands to generate a key pair. We will proceed with the public key. Note that logEncrypt is the passphrase to generate keys, you may use your own.

    openssl genrsa -aes128 -passout pass:logEncrypt -out logging 4096
    openssl rsa -in logging -passin pass:logEncrypt -pubout -out logging.pub
  4. A sample output can be found in the compose folder under example-files. Keep in mind that the logging.pub file containing the public key must be stored in the compose folder along with docker-compose.yml.

    Compress and encrypt the folder, as the compose subsection requires this for the archive value. Use the following command to obtain the base64 encoded archive as a file named compose.b64. Use the raw content of compose.b64 for the value of archive under the compose subsection.

    tar czvf - -C <COMPOSE_FOLDER> . | base64 -w0 > compose.b64
  5. Run the encrypt-basic.sh script to obtain the encrypted workload section of the contract.

    cat workload.yaml | ./encrypt-basic.sh hpcr.crt
  6. Complete the user-data.yaml with the output of Step 2 and 5. Refer to the sample user-data.yaml for the correct schema. Note the hyper-protect-basic token approach to implement hybrid encryption, as it's used throughout Hyper Protect Virtual Servers.

Create your Hyper Protect Virtual Server instance

With the contract (user data) available, we go ahead to create an instance. Follow instructions in Setting up and configuring IBM Hyper Protect Virtual Servers to create an IBM Hyper Protect Virtual Server on a KVM host. Use the contract you created in this tutorial for step 3.c in the Procedure section.

Decrypt log messages

When the virtual server instance is up and running, go to the Log Analysis instance that you provisioned. Open the dashboard and find the ciphertext, which is your encrypted log message.

Use the decrypt-basic.sh along with the private key you generated to decipher the encrypted log message.

echo hyper-protect-basic.rdf...EqM | decrypt-basic.sh logging