<a id="manage-data-in-transit-with-tls"></a>

# Manage Data in Transit with TLS on Confluent Cloud

Confluent Cloud uses the Transport Layer Security (TLS) protocol to provide secure
communication channels between clients and servers, protecting sensitive data
during transmission across networks.

All connections with data in transit to and from Confluent Cloud are encrypted using
TLS. Confluent Cloud services prefer TLS 1.3, with a fallback to TLS 1.2.

TLS 1.3 is supported on all Kafka cluster types:

* Basic, Standard, Freight, and Enterprise
  clusters: Support TLS 1.3 and TLS 1.2. Protocol versions cannot be
  configured and both remain enabled.
* Dedicated clusters:
  : TLS 1.3 is enabled by default on all newly created clusters. For
    Dedicated clusters created before April 30, 2026, TLS 1.3 must
    be enabled. You can manually enable TLS 1.3 by following the steps in
    [Enable TLS 1.3 on Dedicated clusters](#enable-tls-1-3).
    If needed, you can disable TLS 1.2 after enabling TLS 1.3.

All Confluent Cloud cluster types support a shared set of cipher suites. Only
Dedicated clusters can restrict which suites the cluster negotiates.
To learn more, see [Restrict cipher suites](../../clusters/broker-config.md#restrict-ciphers).

For more information about TLS, see:

* [Guidelines for the Selection, Configuration, and Use of Transport Layer Security (TLS) Implementations (NIST Special Publication 800-52 Revision 2)](https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-52r2.pdf)
* [The Transport Layer Security (TLS) Protocol Version 1.3 (RFC 8446)](https://www.rfc-editor.org/rfc/rfc8446)

<a id="supported-cipher-suites"></a>

## Supported cipher suites

Basic, Standard, Enterprise, Dedicated, and Freight clusters support TLS 1.2 and 1.3. To use TLS 1.3 cipher suites
for Dedicated clusters, enable TLS 1.3 on a Dedicated cluster.
See [Enable TLS 1.3 on Dedicated clusters](#enable-tls-1-3).

Confluent Cloud supports the following cipher suites for TLS-encrypted connections.

|   TLS version | Cipher suite                                  | Status      |
|---------------|-----------------------------------------------|-------------|
|           1.3 | `TLS_AES_128_GCM_SHA256`                      | Recommended |
|           1.3 | `TLS_AES_256_GCM_SHA384`                      | Recommended |
|           1.3 | `TLS_CHACHA20_POLY1305_SHA256`                | Recommended |
|           1.2 | `TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256`       | Recommended |
|           1.2 | `TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384`       | Recommended |
|           1.2 | `TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256` | Recommended |
|           1.2 | `TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA`          | Legacy      |
|           1.2 | `TLS_RSA_WITH_AES_128_GCM_SHA256`             | Legacy      |

Cipher suites marked Legacy are only supported for backwards compatibility.
Do not adopt these ciphers for any new deployments.
They also cannot be used with the cipher suite restriction feature.
See [Restrict cipher suites](../../clusters/broker-config.md#restrict-ciphers).

<a id="enable-tls-1-3"></a>

## Enable TLS 1.3 on Dedicated clusters

For Dedicated clusters without TLS 1.3 enabled, you can enable TLS 1.3.
If you have existing clients connected to your Dedicated cluster,
follow these steps to ensure those connections successfully migrate to
TLS 1.3.

1. Update the Kafka broker configuration for your Dedicated cluster to
   use both TLS 1.3 and TLS 1.2 (`ssl.enabled.protocols=TLSv1.3,TLSv1.2`).
   After you update the broker configuration, clients that are configured to
   use TLS 1.3 automatically use TLS 1.3. For details, see
   [Manage TLS protocols](../../clusters/broker-config.md#manage-tls-protocols).
2. Verify the Kafka cluster is using TLS 1.3 by running the
   `confluent kafka cluster configuration describe` command. For details, see
   [Verify TLS protocols](#verify-tls-protocols).
3. Ensure all Kafka clients connecting to the Kafka cluster are configured
   to use TLS 1.3.
   * Java Clients: Set `ssl.enabled.protocols=TLSv1.3,TLSv1.2`. For Java Clients
     version 2.6.0 or later, this is the default behavior.
     * Java Clients older than v. 3.0.2/3.1.1 might experience performance
       degradation when using TLS 1.3. For details, see [Brokers disconnect intermittently
       with TLS1.3 (KAFKA-13418)](https://issues.apache.org/jira/browse/KAFKA-13418).
   * Other clients: Check the documentation for your client library to determine
     how to configure it to use TLS 1.3.
4. Verify all applications are healthy and processing data using TLS 1.3.
5. After confirming that all client applications are able to successfully use
   TLS 1.3 without any issues, you can optionally update the configuration to use
   only TLS 1.3 (`ssl.enabled.protocols=TLSv1.3`). This disables TLS 1.2 on the
   brokers.

   #### IMPORTANT
   Follow a slow roll out as there are older client libraries that don’t
   behave well with TLS 1.3. By initially using both TLS 1.2 and TLS 1.3, you
   can confirm that it works well with TLS 1.3 on the client-side before
   disabling TLS 1.2.
6. Verify again that all applications are healthy and processing data now that
   TLS 1.2 is disabled on the brokers. For details, see
   [Verify TLS protocols](#verify-tls-protocols).

<a id="verify-tls-protocols"></a>

## Verify TLS protocols

You can quickly verify that your Dedicated cluster is using TLS 1.3
using the Confluent CLI.

Use `confluent kafka cluster configuration describe` to check the
`ssl.enabled.protocols` property:

```bash
confluent kafka cluster configuration describe ssl.enabled.protocols \
  --cluster <cluster-id>
```

For example, to verify that your Dedicated cluster `lkc-abc123` is
using TLS 1.3, use the following command:

```bash
confluent kafka cluster configuration describe ssl.enabled.protocols \
  --cluster lkc-abc123
```

The output should be similar to the following:

```text
+-----------+-----------------------+
| Name      | ssl.enabled.protocols |
| Value     | TLSv1.3               |
| Read-Only | true                  |
+-----------+-----------------------+
```

If the `ssl.enabled.protocols` property is set to `TLSv1.3`, then your
Dedicated cluster only uses TLS 1.3. To include TLS 1.2, you can update the
property to `TLSv1.3,TLSv1.2`.

For details on using the `confluent kafka cluster configuration describe`
command, see [confluent kafka cluster configuration describe](https://docs.confluent.io/confluent-cli/current/command-reference/kafka/cluster/configuration/confluent_kafka_cluster_configuration_describe.html).

## Troubleshooting

- The following error indicates that no dynamic
  configuration is set for the flag and the cluster uses TLS 1.2 by default.
  ```none
  Error: configuration "ssl.enabled.protocols" not found
  ```
- Confluent Cloud audit logs capture TLS suite and cipher in the
  [kafka.Authentication event method](../../monitoring/audit-logging/event-methods/authorization-authentication-events.md#kafka-authentication-examples).