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KMS Guide Slack

MinIO uses a key-management-system (KMS) to support SSE-S3. If a client requests SSE-S3, or auto-encryption is enabled, the MinIO server encrypts each object with an unique object key which is protected by a master key managed by the KMS.

Quick Start

MinIO supports multiple KMS implementations via our KES project. We run a KES instance at for you to experiment and quickly get started. To run MinIO with a KMS just fetch the root identity, set the following environment variables and then start your MinIO server. If you havn't installed MinIO, yet, then follow the MinIO install instructions first.

1. Fetch the root identity

As the initial step, fetch the private key and certificate of the root identity:

curl -sSL --tlsv1.2 \
     -O '' \
     -O ''

2. Set the MinIO-KES configuration

export MINIO_KMS_KES_KEY_FILE=root.key
export MINIO_KMS_KES_CERT_FILE=root.cert
export MINIO_KMS_KES_KEY_NAME=my-minio-key

3. Start the MinIO Server

export MINIO_ROOT_USER=minio
export MINIO_ROOT_PASSWORD=minio123
minio server ~/export

The KES instance at is meant to experiment and provides a way to get started quickly. Note that anyone can access or delete master keys at You should run your own KES instance in production.

Configuration Guides

A typical MinIO deployment that uses a KMS for SSE-S3 looks like this:

    │ ┌──────────┴─┬─────╮          ┌────────────┐
    └─┤ ┌──────────┴─┬───┴──────────┤ ┌──────────┴─┬─────────────────╮
      └─┤ ┌──────────┴─┬─────┬──────┴─┤ KES Server ├─────────────────┤
        └─┤   MinIO    ├─────╯        └────────────┘            ┌────┴────┐
          └────────────┘                                        │   KMS   │

In a given setup, there are n MinIO instances talking to m KES servers but only 1 central KMS. The most simple setup consists of 1 MinIO server or cluster talking to 1 KMS via 1 KES server.

The main difference between various MinIO-KMS deployments is the KMS implementation. The following table helps you select the right option for your use case:

KMS Purpose
Hashicorp Vault Local KMS. MinIO and KMS on-prem (Recommended)
AWS-KMS + SecretsManager Cloud KMS. MinIO in combination with a managed KMS installation
Gemalto KeySecure /Thales CipherTrust Local KMS. MinIO and KMS On-Premises.
Google Cloud Platform SecretManager Cloud KMS. MinIO in combination with a managed KMS installation
FS Local testing or development (Not recommended for production)

The MinIO-KES configuration is always the same - regardless of the underlying KMS implementation. Checkout the MinIO-KES configuration example.

Further references

Auto Encryption

Auto-Encryption is useful when MinIO administrator wants to ensure that all data stored on MinIO is encrypted at rest.

Using mc encrypt (recommended)

MinIO automatically encrypts all objects on buckets if KMS is successfully configured and bucket encryption configuration is enabled for each bucket as shown below:

mc encrypt set sse-s3 myminio/bucket/

Verify if MinIO has sse-s3 enabled

mc encrypt info myminio/bucket/
Auto encryption 'sse-s3' is enabled

Using environment (not-recommended)

MinIO automatically encrypts all objects on buckets if KMS is successfully configured and following ENV is enabled:


Verify auto-encryption

Note that auto-encryption only affects requests without S3 encryption headers. So, if a S3 client sends e.g. SSE-C headers, MinIO will encrypt the object with the key sent by the client and won't reach out to the configured KMS.

To verify auto-encryption, use the following mc command:

mc cp test.file myminio/bucket/
test.file:              5 B / 5 B  ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓  100.00% 337 B/s 0s
mc stat myminio/bucket/test.file
Name      : test.file
Encrypted :
  X-Amz-Server-Side-Encryption: AES256

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