Network Encryption (TLS)

Table of Contents

Enabling TLS
Third-Party Certificate Authorities

MinIO supports Transport Layer Security (TLS) 1.2+ encryption of incoming and outgoing traffic.

SSL is Deprecated

TLS is the successor to Secure Socket Layer (SSL) encryption. SSL is fully deprecated as of June 30th, 2018.

Enabling TLS

The MinIO server searches the following directory for TLS keys and certificates:

${HOME}/.minio/certs

Where ${HOME} is the home directory of the user running the MinIO Server process.

For deployments started with a custom TLS directory minio server --certs-dir, use that directory instead of the defaults.

Place the TLS certificates for the default domain (e.g. minio.example.net) in the /certs directory, with the private key as private.key and public certificate as public.crt.

For example:

${HOME}/.minio/certs
  private.key
  public.crt

You can use the MinIO certgen to mint self-signed certificates for enabling TLS for evaluating MinIO with TLS enabled. For example, the following command generates a self-signed certificate with a set of IP and DNS SANs associated to the MinIO Server hosts:

certgen -host "localhost,minio-*.example.net"

You can place the generated public.crt and private.key into the /.minio/certs directory to enable TLS for the MinIO deployment. Applications can use the public.crt as a trusted Certificate Authority to allow connections to the MinIO deployment without disabling certificate validation.

Multiple Domain-Based TLS Certificates

The MinIO server supports multiple TLS certificates, where the server uses Server Name Indication (SNI) to identify which certificate to use when responding to a client request. When a client connects using a specific hostname, MinIO uses SNI to select the appropriate TLS certificate for that hostname.

For example, consider a MinIO deployment reachable through the following hostnames:

https://minio.example.net (default TLS certificates)
https://s3.example.net
https://minio.internal-example.net

Create a subfolder in /certs for each additional domain for which MinIO should present TLS certificates. While MinIO has no requirements for folder names, consider creating subfolders whose name matches the domain to improve human readability. Place the TLS private and public key for that domain in the subfolder.

For example:

${HOME}/.minio/certs
  private.key
  public.crt
  s3-example.net/
    private.key
    public.crt
  internal-example.net/
    private.key
    public.crt

While you can have a single TLS certificate that covers all hostnames with multiple Subject Alternative Names (SAN), this would reveal the internal-example.net and s3-example.net hostnames to any client which inspects the server certificate. Using a TLS certificate per hostname better protects each individual hostname from discovery.

If the client-specified hostname or IP address does not match any of the configured TLS certificates, the connection typically fails with a certificate validation error.

Supported TLS Cipher Suites

MinIO recommends generating ECDSA (e.g. NIST P-256 curve) or EdDSA (e.g. Curve25519) TLS private keys/certificates due to their lower computation requirements compared to RSA.

MinIO supports the following TLS 1.2 and 1.3 cipher suites as supported by Go. The lists mark recommended algorithms with a icon:

TLS 1.3

TLS_CHACHA20_POLY1305_SHA256
TLS_AES_128_GCM_SHA256
TLS_AES_256_GCM_SHA384

TLS 1.2

TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305
TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256
TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384
TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305
TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384

Third-Party Certificate Authorities

The MinIO Server validates the TLS certificate presented by each connecting client against the host system’s trusted root certificate store.

You can place additional trusted Certificate Authority files in the following directory:

${HOME}/.minio/certs/CAs

Where ${HOME} is the home directory of the user running the MinIO Server process.

For deployments started with a custom TLS directory minio server --certs-dir, the server searches in the /CAs path at that specified directory.

Place the certificate file for each CA into the /CAs subdirectory. Ensure all hosts in the MinIO deployment have a consistent set of trusted CAs in that directory. If the MinIO Server cannot match an incoming client’s TLS certificate issuer against any of the available CAs, the server rejects the connection as invalid.