KES on a MinIO Deployment

This tutorial shows how to setup a KES server and then configure a MinIO deployment as a KES client for object encryption.

M i n I O K E S S e r v e r K M S
For testing only:

This tutorial focuses on a simple KES server setup. We use the local filesystem as key store and omit the KMS integration.

For production use, choose any supported KMS implementation that meets your requirements.

KES Server Setup

  1. Generate KES Server Private Key & Certificate

    Generate a TLS private key and certificate for the KES server. This key is used for domain name verification for the server address.

    A KES server is secure-by-default and can only be run with TLS. In this guide, we use self-signed certificates for simplicity.

    The following command generates a new TLS private key (private.key) and a self-signed X.509 certificate (public.crt) issued for the IP and DNS name localhost:

    $ kes identity new --ip "" localhost
      Private key:  private.key
      Certificate:  public.crt
      Identity:     2e897f99a779cf5dd147e58de0fe55a494f546f4dcae8bc9e5426d2b5cd35680
    Existing Key & Certificate:
    If you already have a TLS private key & certificate, such as from a WebPKI or internal Certificate Authority, you can use them instead. Remember to adjust the tls config section.
  2. Generate MinIO Credentials

    MinIO needs credentials to access the KES server. The following command generates a hashed identity from a provided TLS private/public key pair:

    $ kes identity new --key=client.key --cert=client.crt MinIO
      Private key:  client.key
      Certificate:  client.crt
      Identity:     02ef5321ca409dbc7b10e7e8ee44d1c3b91e4bf6e2198befdebee6312745267b

    The identity 02ef5321ca409dbc7b10e7e8ee44d1c3b91e4bf6e2198befdebee6312745267b is a unique fingerprint of the public key in client.crt. Use this API key identity to validate the MinIO client to the KES server.

    You can re-compute the identity from the same certificate at any time:

    $ kes identity of client.crt
      Identity:  02ef5321ca409dbc7b10e7e8ee44d1c3b91e4bf6e2198befdebee6312745267b
  3. Configure KES Server

    This procedure provides a baseline set of steps that may require significant alteration to fit your goals. For detailed instructions on configuring the KES Server for a specific Key Management System provider, see the integration page for supported targets.

    Create the KES server configuration file: config.yml. Ensure the identity in the policy section matches your client.crt identity.

    address: # Listen on all network interfaces on port 7373
      identity: disabled  # We disable the admin identity since we don't need it in this guide 
      key: private.key    # The KES server TLS private key
      cert: public.crt    # The KES server TLS certificate
        - /v1/key/create/minio-*
        - /v1/key/generate/minio-*
        - /v1/key/decrypt/minio-*
        - 02ef5321ca409dbc7b10e7e8ee44d1c3b91e4bf6e2198befdebee6312745267b # Use the identity of your client.crt
        path: ./keys # Choose a directory for the secret keys
  4. Start KES Server

    kes server --config config.yml --auth off
    Linux Swap Protection:

    In Linux environments, KES can use the mlock syscall to prevent the OS from writing in-memory data to disk (swapping). This prevents leaking sensitive data.

    Use the following command to allow KES to use the mlock syscall without running with root privileges:

    sudo setcap cap_ipc_lock=+ep $(readlink -f $(which kes))

    Start a KES server instance with memory protection:

    kes server --config config.yml --auth off --mlock

MinIO Server Setup

The environment variables defined in steps 2-6 below can be defined as part of the MinIO Server environment variable file.

  1. Install MinIO

    You can either download a static binary or follow the MinIO Quickstart Guide.

    For more detailed instructions on setting up a MinIO Server on other topologies, such as with multiple drives or multiple nodes, see the installation documentation.

    Select the tab for your operating system for an OS-specific quickstart.


    This environment variable tells MinIO which KES server to access:

  3. Set MinIO Client Credentials

    These environment variables set the access credentials MinIO uses to access the KES server:

    export MINIO_KMS_KES_CERT_FILE=client.crt
    export MINIO_KMS_KES_KEY_FILE=client.key
  4. Set MinIO Default Key

    This environment variable sets the default key for MinIO to use if its S3 client does not specify an encryption key.

    export MINIO_KMS_KES_KEY_NAME=minio-default-key
    MinIO creates this key automatically if it does not exist.
  5. Trust the KES Server Certificate

    This step is optional if the KES server uses a certificate issued by a trusted Certificate Authority.

    When using self-signed certificates, MinIO cannot verify the the KES server certificate. This environment variable establishes the trust relationship manually.

    export MINIO_KMS_KES_CAPATH=public.crt

    In this case, public.crt is the public certificate of the KES server.

  6. Set the MinIO root credentials:

    export MINIO_ROOT_USER=minio
    export MINIO_ROOT_PASSWORD=minio123
  7. Start the MinIO Server

    The KES server must be running before you start the MinIO Server. The MinIO Server requires access to the KES server as part of the start-up process.
    minio server /data

Encrypt Bucket

Enable server-side encryption on a specific bucket using the PutBucketEncryption S3 API. This can be done with the MinIO Client.

  1. Create Key

    For a full reference, see the mc admin kms key documentation.

    mc admin kms key create <alias> minio-key-name

    Replace minio-key-name with the name to use for your key.

  2. Configure Bucket

    Add a server-side encryption configuration to your bucket with mc encrypt set.

    For example:

    mc encrypt set sse-kms minio-key-name <alias>/my-bucket

    Replace minio-key-name with the name of the key you created in the previous step.