Key Encryption Service Settings

MinIO Server includes three groups of environment variables to manage how the MinIO Server interacts with the Key Encryption Service (KES), Key Management Service (KMS), or static key files. You may only define one of the three sets. If more than one type of environment variable sets is defined, MinIO returns an error.

Note

These settings do not have configuration setting options for use with mc admin config set.

Define any one set of these environment variables in the host system prior to starting or restarting the MinIO process. Refer to your operating system’s documentation for how to define an environment variable.

Important

Each configuration setting controls fundamental MinIO behavior and functionality. MinIO strongly recommends testing configuration changes in a lower environment, such as DEV or QA, before applying to production.

Key Encryption Service

Define the following variables to use the Key Encryption Service (KES) to connect to a supported 3rd party Key Management Service provider.

`MINIO_KMS_KES_ENDPOINT`

envvar

The endpoint(s) for the MinIO Key Encryption Service (KES) process to use for supporting SSE-S3 and MinIO backend encryption operations. Separate multiple KES endpoints with a ,.

`MINIO_KMS_KES_KEY_NAME`

envvar

The name of an external key on the Key Management system (KMS) configured on the KES server and used for performing en/decryption operations. MinIO uses this key for the following:

Encrypting backend data (IAM, server configuration).
The default encryption key for Server-Side Encryption with SSE-KMS.
The encryption key for Server-Side Encryption with SSE-S3.

Important

Enabling SSE on a MinIO deployment automatically encrypts the backend data for that deployment using the default encryption key.

MinIO requires access to KES and the external KMS to decrypt the backend and start normally. The KMS must maintain and provide access to the MINIO_KMS_KES_KEY_NAME. You cannot disable KES later or “undo” the SSE configuration at a later point.

`MINIO_KMS_KES_API_KEY`

envvar

Preferred method for authenticating with the encryption service using the KES API key obtained from the kes identity new command.

This environment variable is mutually exclusive with the MINIO_KMS_KES_KEY_FILE and MINIO_KMS_KES_CERT_FILE environment variables.

`MINIO_KMS_KES_KEY_FILE`

envvar

The private key associated to the the MINIO_KMS_KES_CERT_FILE x.509 certificate to use when authenticating to the KES server. The KES server requires clients to present their certificate for performing mutual TLS (mTLS).

See the KES wiki for more complete documentation on KES access control.

You must also set the MINIO_KMS_KES_CERT_FILE. This variable is mutually exclusive with MINIO_KMS_KES_API_KEY.

`MINIO_KMS_KES_CERT_FILE`

envvar

The x.509 certificate to present to the KES server. The KES server requires clients to present their certificate for performing mutual TLS (mTLS).

The KES server computes an identity from the certificate and compares it to its configured policies. The KES server grants the minio server access to only those operations explicitly granted by the policy.

See the KES wiki for more complete documentation on KES access control.

You must also set the MINIO_KMS_KES_KEY_FILE. This variable is mutually exclusive with MINIO_KMS_KES_API_KEY.

`MINIO_KMS_KES_CAPATH`

envvar

Optional

Allows validation of the KES Server Certificate for a Self-Signed or Third-Party CA. Specify the path to the location of the CA certificate for your KES deployment.

This variable is not required if you use a public certificate authority.

`MINIO_KMS_KES_KEY_PASSWORD`

envvar

Optional

The password used to encrypt and decrypt the TLS private key, if used.

MinIO Key Management Server (KMS)

Define the following variables to use MinIO KMS to manage keys.

`MINIO_KMS_SERVER`

envvar

The endpoint(s) for the MinIO Key Management Service (KMS) process to use for supporting SSE-S3 and MinIO backend encryption operations. Separate multiple KMS endpoints with a ,.

`MINIO_KMS_ENCLAVE`

envvar

The MinIO KMS Enclave where the key and identity exist.

`MINIO_KMS_SSE_KEY`

envvar

The default key to use for SSE-S3 encryption when a call does not specify a key identity.

`MINIO_KMS_API_KEY`

envvar

The credential used to authenticate with the MinIO KMS service.

Static Key Files

Warning

These settings support early development and evaluation of Server-Side Encryption of Objects without depending on an external KMS. Do not use these settings in any extended development, QA, or production environments. See Server-Side Object Encryption with KES for guidance on deploying SSE using MinIO Key Encryption Service (KES) and an external KMS.

Provide a static KMS key or key file to use for encryption.

`MINIO_KMS_SECRET_KEY`

envvar

The base64 form of the static KMS key in the form <key-name>:<base64-32byte-key>. Implements a subset of KMS APIs.

`MINIO_KMS_SECRET_KEY_FILE`

envvar

Path to the file to read the static KMS key from.

Last modified August 2, 2026: init commit (8338d5b)