8.3.2 Encrypted Connection TLS Protocols and Ciphers (original) (raw)

8.3.2 Encrypted Connection TLS Protocols and Ciphers

MySQL supports multiple TLS protocols and ciphers, and enables configuring which protocols and ciphers to permit for encrypted connections. It is also possible to determine which protocol and cipher the current session uses.

Supported TLS Protocols

The set of protocols permitted for connections to a given MySQL server instance is subject to multiple factors as follows:

MySQL Server release

Up to and including MySQL 8.0.15, MySQL supports the TLSv1, TLSv1.1, and TLSv1.2 protocols.
As of MySQL 8.0.16, MySQL also supports the TLSv1.3 protocol. To use TLSv1.3, both the MySQL server and the client application must be compiled using OpenSSL 1.1.1 or higher. The Group Replication component supports TLSv1.3 from MySQL 8.0.18 (for details, seeSection 20.6.2, “Securing Group Communication Connections with Secure Socket Layer (SSL)”).
As of MySQL 8.0.26, the TLSv1 and TLSv1.1 protocols are deprecated. These protocol versions are old, released in 1996 and 2006, respectively, and the algorithms used are weak and outdated. For background, refer to the IETF memoDeprecating TLSv1.0 and TLSv1.1.
As of MySQL 8.0.28, MySQL no longer supports the TLSv1 and TLSv1.1 protocols. From this release, clients cannot make a TLS/SSL connection with the protocol set to TLSv1 or TLSv1.1. For more details, seeRemoval of Support for the TLSv1 and TLSv1.1 Protocols.

Table 8.13 MySQL Server TLS Protocol Support

MySQL Server Release	TLS Protocols Supported
MySQL 8.0.15 and below	TLSv1, TLSv1.1, TLSv1.2
MySQL 8.0.16 and MySQL 8.0.17	TLSv1, TLSv1.1, TLSv1.2, TLSv1.3 (except Group Replication)
MySQL 8.0.18 through MySQL 8.0.25	TLSv1, TLSv1.1, TLSv1.2, TLSv1.3 (including Group Replication)
MySQL 8.0.26 and MySQL 8.0.27	TLSv1 (deprecated), TLSv1.1 (deprecated), TLSv1.2, TLSv1.3
MySQL 8.0.28 and above	TLSv1.2, TLSv1.3

SSL library

If the SSL library does not support a particular protocol, neither does MySQL, and any parts of the following discussion that specify that protocol do not apply. In particular, note that to use TLSv1.3, both the MySQL server and the client application must be compiled using OpenSSL 1.1.1 or higher. MySQL Server checks the version of OpenSSL at startup, and if it is lower than 1.1.1, TLSv1.3 is removed from the default value for the server system variables relating to TLS versions (tls_version,admin_tls_version, andgroup_replication_recovery_tls_version).

MySQL instance configuration

Permitted TLS protocols can be configured on both the server side and client side to include only a subset of the supported TLS protocols. The configuration on both sides must include at least one protocol in common or connection attempts cannot negotiate a protocol to use. For details, seeConnection TLS Protocol Negotiation.

System-wide host configuration

The host system may permit only certain TLS protocols, which means that MySQL connections cannot use nonpermitted protocols even if MySQL itself permits them:

Suppose that MySQL configuration permits TLSv1, TLSv1.1, and TLSv1.2, but your host system configuration permits only connections that use TLSv1.2 or higher. In this case, you cannot establish MySQL connections that use TLSv1 or TLSv1.1, even though MySQL is configured to permit them, because the host system does not permit them.
If MySQL configuration permits TLSv1, TLSv1.1, and TLSv1.2, but your host system configuration permits only connections that use TLSv1.3 or higher, you cannot establish MySQL connections at all, because no protocol permitted by MySQL is permitted by the host system.

Workarounds for this issue include:

Change the system-wide host configuration to permit additional TLS protocols. Consult your operating system documentation for instructions. For example, your system may have an/etc/ssl/openssl.cnf file that contains these lines to restrict TLS protocols to TLSv1.2 or higher:

[system_default_sect]  
MinProtocol = TLSv1.2

Changing the value to a lower protocol version orNone makes the system more permissive. This workaround has the disadvantage that permitting lower (less secure) protocols may have adverse security consequences.

If you cannot or prefer not to change the host system TLS configuration, change MySQL applications to use higher (more secure) TLS protocols that are permitted by the host system. This may not be possible for older versions of MySQL that support only lower protocol versions. For example, TLSv1 is the only supported protocol prior to MySQL 5.6.46, so attempts to connect to a pre-5.6.46 server fail even if the client is from a newer MySQL version that supports higher protocol versions. In such cases, an upgrade to a version of MySQL that supports additional TLS versions may be required.

Removal of Support for the TLSv1 and TLSv1.1 Protocols

Support for the TLSv1 and TLSv1.1 connection protocols is removed as of MySQL 8.0.28. The protocols were deprecated from MySQL 8.0.26. For background information, refer toRFC 8996 (Deprecating TLS 1.0 and TLS 1.1). It is recommended that connections be made using the more-secure TLSv1.2 and TLSv1.3 protocols. TLSv1.3 requires that both the MySQL server and the client application are compiled with OpenSSL 1.1.1.

Support for TLSv1 and TLSv1.1 is removed because those protocol versions are old, released in 1996 and 2006, respectively. The algorithms used are weak and outdated. Unless you are using very old versions of MySQL Server or connectors, you are unlikely to have connections using TLSv1.0 or TLSv1.1. MySQL connectors and clients select the highest TLS version available by default.

In the releases where the TLSv1 and TLSv1.1 connection protocols are unsupported (from MySQL 8.0.28 onwards), clients, including MySQL Shell, that support a--tls-version option for specifying TLS protocols for connections to the MySQL server cannot make a TLS/SSL connection with the protocol set to TLSv1 or TLSv1.1. If a client attempts to connect using these protocols, for TCP connections, the connection fails, and an error is returned to the client. For socket connections, if--ssl-mode is set toREQUIRED, the connection fails, otherwise the connection is made but with TLS/SSL disabled.

On the server side, the following settings are changed from MySQL 8.0.28:

The default values of the server’stls_version andadmin_tls_version system variables no longer include TLSv1 and TLSv1.1.
The default value of the Group Replication system variablegroup_replication_recovery_tls_version no longer includes TLSv1 and TLSv1.1.
For asynchronous replication, replicas cannot set the protocol for connections to the source server to TLSv1 or TLSv1.1 (the SOURCE_TLS_VERSION option of the CHANGE REPLICATION SOURCE TO statement).

In the releases where the TLSv1 and TLSv1.1 connection protocols are deprecated (MySQL 8.0.26 and MySQL 8.0.27), the server writes a warning to the error log if they are included in the values of the tls_version oradmin_tls_version system variable, and if a client successfully connects using them. A warning is also returned if you set the deprecated protocols at runtime and implement them using the ALTER INSTANCE RELOAD TLS statement. Clients, including replicas that specify TLS protocols for connections to the source server and Group Replication group members that specify TLS protocols for distributed recovery connections, do not issue warnings if they are configured to permit a deprecated TLS protocol.

For more information, seeDoes MySQL 8.0 support TLS 1.0 and 1.1?

Connection TLS Protocol Configuration

On the server side, the value of thetls_version system variable determines which TLS protocols a MySQL server permits for encrypted connections. Thetls_version value applies to connections from clients, regular source/replica replication connections where this server instance is the source, Group Replication group communication connections, and Group Replication distributed recovery connections where this server instance is the donor. The administrative connection interface is configured similarly, but uses theadmin_tls_version system variable (seeSection 7.1.12.2, “Administrative Connection Management”). This discussion applies toadmin_tls_version as well.

The tls_version value is a list of one or more comma-separated TLS protocol versions, which is not case-sensitive. By default, this variable lists all protocols that are supported by the SSL library used to compile MySQL and by the MySQL Server release. The default settings are therefore as shown in Table 8.14, “MySQL Server TLS Protocol Default Settings”.

Table 8.14 MySQL Server TLS Protocol Default Settings

MySQL Server Release	tls_version Default Setting
MySQL 8.0.15 and below	TLSv1,TLSv1.1,TLSv1.2
MySQL 8.0.16 and MySQL 8.0.17	TLSv1,TLSv1.1,TLSv1.2,TLSv1.3 (with OpenSSL 1.1.1) TLSv1,TLSv1.1,TLSv1.2 (otherwise) Group Replication does not support TLSv1.3
MySQL 8.0.18 through MySQL 8.0.25	TLSv1,TLSv1.1,TLSv1.2,TLSv1.3 (with OpenSSL 1.1.1) TLSv1,TLSv1.1,TLSv1.2 (otherwise) Group Replication supports TLSv1.3
MySQL 8.0.26 and MySQL 8.0.27	TLSv1,TLSv1.1,TLSv1.2,TLSv1.3 (with OpenSSL 1.1.1) TLSv1,TLSv1.1,TLSv1.2 (otherwise) TLSv1 and TLSv1.1 are deprecated
MySQL 8.0.28 and above	TLSv1.2,TLSv1.3

To determine the value oftls_version at runtime, use this statement:

mysql> SHOW GLOBAL VARIABLES LIKE 'tls_version';
+---------------+-----------------------+
| Variable_name | Value                 |
+---------------+-----------------------+
| tls_version   | TLSv1.2,TLSv1.3       |
+---------------+-----------------------+

To change the value oftls_version, set it at server startup. For example, to permit connections that use the TLSv1.2 or TLSv1.3 protocol, but prohibit connections that use the less-secure TLSv1 and TLSv1.1 protocols, use these lines in the server my.cnf file:

[mysqld]
tls_version=TLSv1.2,TLSv1.3

To be even more restrictive and permit only TLSv1.3 connections, set tls_version like this:

[mysqld]
tls_version=TLSv1.3

As of MySQL 8.0.16, tls_version can be changed at runtime. SeeServer-Side Runtime Configuration and Monitoring for Encrypted Connections.

On the client side, the--tls-version option specifies which TLS protocols a client program permits for connections to the server. The format of the option value is the same as for the tls_version system variable described previously (a list of one or more comma-separated protocol versions).

For source/replica replication connections where this server instance is the replica, theSOURCE_TLS_VERSION |MASTER_TLS_VERSION option for theCHANGE REPLICATION SOURCE TO statement (from MySQL 8.0.23) or CHANGE MASTER TO statement (before MySQL 8.0.23) specifies which TLS protocols the replica permits for connections to the source. The format of the option value is the same as for thetls_version system variable described previously. SeeSection 19.3.1, “Setting Up Replication to Use Encrypted Connections”.

The protocols that can be specified forSOURCE_TLS_VERSION |MASTER_TLS_VERSION depend on the SSL library. This option is independent of and not affected by the servertls_version value. For example, a server that acts as a replica can be configured withtls_version set to TLSv1.3 to permit only incoming connections that use TLSv1.3, but also configured with SOURCE_TLS_VERSION |MASTER_TLS_VERSION set to TLSv1.2 to permit only TLSv1.2 for outgoing replica connections to the source.

For Group Replication distributed recovery connections where this server instance is the joining member that initiates distributed recovery (that is, the client), thegroup_replication_recovery_tls_version system variable specifies which protocols are permitted by the client. Again, this option is independent of and not affected by the server tls_version value, which applies when this server instance is the donor. A Group Replication server generally participates in distributed recovery both as a donor and as a joining member over the course of its group membership, so both these system variables should be set. SeeSection 20.6.2, “Securing Group Communication Connections with Secure Socket Layer (SSL)”.

TLS protocol configuration affects which protocol a given connection uses, as described inConnection TLS Protocol Negotiation.

Permitted protocols should be chosen such as not to leave“holes” in the list. For example, these server configuration values do not have holes:

tls_version=TLSv1,TLSv1.1,TLSv1.2,TLSv1.3
tls_version=TLSv1.1,TLSv1.2,TLSv1.3
tls_version=TLSv1.2,TLSv1.3
tls_version=TLSv1.3

These values do have holes and should not be used:

tls_version=TLSv1,TLSv1.2       (TLSv1.1 is missing)
tls_version=TLSv1.1,TLSv1.3     (TLSv1.2 is missing)

The prohibition on holes also applies in other configuration contexts, such as for clients or replicas.

Unless you intend to disable encrypted connections, the list of permitted protocols should not be empty. If you set a TLS version parameter to the empty string, encrypted connections cannot be established:

tls_version: The server does not permit encrypted incoming connections.
--tls-version: The client does not permit encrypted outgoing connections to the server.
SOURCE_TLS_VERSION |MASTER_TLS_VERSION: The replica does not permit encrypted outgoing connections to the source.
group_replication_recovery_tls_version: The joining member does not permit encrypted connections to the distributed recovery connection.

Connection Cipher Configuration

A default set of ciphers applies to encrypted connections, which can be overridden by explicitly configuring the permitted ciphers. During connection establishment, both sides of a connection must permit some cipher in common or the connection fails. Of the permitted ciphers common to both sides, the SSL library chooses the one supported by the provided certificate that has the highest priority.

To specify a cipher or ciphers applicable for encrypted connections that use TLS protocols up through TLSv1.2:

Set the ssl_cipher system variable on the server side, and use the--ssl-cipher option for client programs.
For regular source/replica replication connections, where this server instance is the source, set thessl_cipher system variable. Where this server instance is the replica, use theSOURCE_SSL_CIPHER |MASTER_SSL_CIPHER option for theCHANGE REPLICATION SOURCE TO statement (from MySQL 8.0.23) or CHANGE MASTER TO statement (before MySQL 8.0.23). SeeSection 19.3.1, “Setting Up Replication to Use Encrypted Connections”.
For a Group Replication group member, for Group Replication group communication connections and also for Group Replication distributed recovery connections where this server instance is the donor, set thessl_cipher system variable. For Group Replication distributed recovery connections where this server instance is the joining member, use thegroup_replication_recovery_ssl_cipher system variable. SeeSection 20.6.2, “Securing Group Communication Connections with Secure Socket Layer (SSL)”.

For encrypted connections that use TLSv1.3, OpenSSL 1.1.1 and higher supports the following ciphersuites, the first three of which are enabled by default:

TLS_AES_128_GCM_SHA256
TLS_AES_256_GCM_SHA384
TLS_CHACHA20_POLY1305_SHA256
TLS_AES_128_CCM_SHA256

Note

Prior to MySQL 8.0.35,TLS_AES_128_CCM_8_SHA256 was supported for use with server system variables--tls-ciphersuites or--admin-tls-ciphersuites.TLS_AES_128_CCM_8_SHA256 generates a deprecation warning if configured for MySQL 8.0.35 and higher.

To configure the permitted TLSv1.3 ciphersuites explicitly, set the following parameters. In each case, the configuration value is a list of zero or more colon-separated ciphersuite names.

On the server side, use thetls_ciphersuites system variable. If this variable is not set, its default value isNULL, which means that the server permits the default set of ciphersuites. If the variable is set to the empty string, no ciphersuites are enabled and encrypted connections cannot be established.
On the client side, use the--tls-ciphersuites option. If this option is not set, the client permits the default set of ciphersuites. If the option is set to the empty string, no ciphersuites are enabled and encrypted connections cannot be established.
For regular source/replica replication connections, where this server instance is the source, use thetls_ciphersuites system variable. Where this server instance is the replica, use theSOURCE_TLS_CIPHERSUITES |MASTER_TLS_CIPHERSUITES option for theCHANGE REPLICATION SOURCE TO statement (from MySQL 8.0.23) or CHANGE MASTER TO statement (before MySQL 8.0.23). SeeSection 19.3.1, “Setting Up Replication to Use Encrypted Connections”.
For a Group Replication group member, for Group Replication group communication connections and also for Group Replication distributed recovery connections where this server instance is the donor, use thetls_ciphersuites system variable. For Group Replication distributed recovery connections where this server instance is the joining member, use thegroup_replication_recovery_tls_ciphersuites system variable. SeeSection 20.6.2, “Securing Group Communication Connections with Secure Socket Layer (SSL)”.

Note

Ciphersuite support is available as of MySQL 8.0.16, but requires that both the MySQL server and the client application be compiled using OpenSSL 1.1.1 or higher.

In MySQL 8.0.16 through 8.0.18, thegroup_replication_recovery_tls_ciphersuites system variable and theSOURCE_TLS_CIPHERSUITES |MASTER_TLS_CIPHERSUITES option for theCHANGE REPLICATION SOURCE TO statement (from MySQL 8.0.23) or CHANGE MASTER TO statement (before MySQL 8.0.23) are not available. In these releases, if TLSv1.3 is used for source/replica replication connections, or in Group Replication for distributed recovery (supported from MySQL 8.0.18), the replication source or Group Replication donor servers must permit the use of at least one TLSv1.3 ciphersuite that is enabled by default. From MySQL 8.0.19, you can use the options to configure client support for any selection of ciphersuites, including only non-default ciphersuites if you want.

A given cipher may work only with particular TLS protocols, which affects the TLS protocol negotiation process. SeeConnection TLS Protocol Negotiation.

To determine which ciphers a given server supports, check the session value of theSsl_cipher_list status variable:

SHOW SESSION STATUS LIKE 'Ssl_cipher_list';

The Ssl_cipher_list status variable lists the possible SSL ciphers (empty for non-SSL connections). If MySQL supports TLSv1.3, the value includes the possible TLSv1.3 ciphersuites.

Note

ECDSA ciphers only work in combination with an SSL certificate that uses ECDSA for the digital signature, and they do not work with certificates that use RSA. MySQL Server’s automatic generation process for SSL certificates does not generate ECDSA signed certificates, it generates only RSA signed certificates. Do not select ECDSA ciphers unless you have an ECDSA certificate available to you.

For encrypted connections that use TLS.v1.3, MySQL uses the SSL library default ciphersuite list.

For encrypted connections that use TLS protocols up through TLSv1.2, MySQL passes the following default cipher list to the SSL library.

ECDHE-ECDSA-AES128-GCM-SHA256
ECDHE-ECDSA-AES256-GCM-SHA384
ECDHE-RSA-AES128-GCM-SHA256
ECDHE-RSA-AES256-GCM-SHA384
ECDHE-ECDSA-CHACHA20-POLY1305
ECDHE-RSA-CHACHA20-POLY1305
ECDHE-ECDSA-AES256-CCM
ECDHE-ECDSA-AES128-CCM
DHE-RSA-AES128-GCM-SHA256
DHE-RSA-AES256-GCM-SHA384
DHE-RSA-AES256-CCM
DHE-RSA-AES128-CCM
DHE-RSA-CHACHA20-POLY1305

These cipher restrictions are in place:

As of MySQL 8.0.35, the following ciphers are deprecated and produce a warning when used with the server system variables--ssl-cipher and--admin-ssl-cipher:

ECDHE-ECDSA-AES128-SHA256  
ECDHE-RSA-AES128-SHA256  
ECDHE-ECDSA-AES256-SHA384  
ECDHE-RSA-AES256-SHA384  
DHE-DSS-AES128-GCM-SHA256  
DHE-RSA-AES128-SHA256  
DHE-DSS-AES128-SHA256  
DHE-DSS-AES256-GCM-SHA384  
DHE-RSA-AES256-SHA256  
DHE-DSS-AES256-SHA256  
ECDHE-RSA-AES128-SHA  
ECDHE-ECDSA-AES128-SHA  
ECDHE-RSA-AES256-SHA  
ECDHE-ECDSA-AES256-SHA  
DHE-DSS-AES128-SHA  
DHE-RSA-AES128-SHA  
TLS_DHE_DSS_WITH_AES_256_CBC_SHA  
DHE-RSA-AES256-SHA  
AES128-GCM-SHA256  
DH-DSS-AES128-GCM-SHA256  
ECDH-ECDSA-AES128-GCM-SHA256  
AES256-GCM-SHA384  
DH-DSS-AES256-GCM-SHA384  
ECDH-ECDSA-AES256-GCM-SHA384  
AES128-SHA256  
DH-DSS-AES128-SHA256  
ECDH-ECDSA-AES128-SHA256  
AES256-SHA256  
DH-DSS-AES256-SHA256  
ECDH-ECDSA-AES256-SHA384  
AES128-SHA  
DH-DSS-AES128-SHA  
ECDH-ECDSA-AES128-SHA  
AES256-SHA  
DH-DSS-AES256-SHA  
ECDH-ECDSA-AES256-SHA  
DH-RSA-AES128-GCM-SHA256  
ECDH-RSA-AES128-GCM-SHA256  
DH-RSA-AES256-GCM-SHA384  
ECDH-RSA-AES256-GCM-SHA384  
DH-RSA-AES128-SHA256  
ECDH-RSA-AES128-SHA256  
DH-RSA-AES256-SHA256  
ECDH-RSA-AES256-SHA384  
ECDHE-RSA-AES128-SHA  
ECDHE-ECDSA-AES128-SHA  
ECDHE-RSA-AES256-SHA  
ECDHE-ECDSA-AES256-SHA  
DHE-DSS-AES128-SHA  
DHE-RSA-AES128-SHA  
TLS_DHE_DSS_WITH_AES_256_CBC_SHA  
DHE-RSA-AES256-SHA  
AES128-SHA  
DH-DSS-AES128-SHA  
ECDH-ECDSA-AES128-SHA  
AES256-SHA  
DH-DSS-AES256-SHA  
ECDH-ECDSA-AES256-SHA  
DH-RSA-AES128-SHA  
ECDH-RSA-AES128-SHA  
DH-RSA-AES256-SHA  
ECDH-RSA-AES256-SHA  
DES-CBC3-SHA

The following ciphers are permanently restricted:

!DHE-DSS-DES-CBC3-SHA  
!DHE-RSA-DES-CBC3-SHA  
!ECDH-RSA-DES-CBC3-SHA  
!ECDH-ECDSA-DES-CBC3-SHA  
!ECDHE-RSA-DES-CBC3-SHA  
!ECDHE-ECDSA-DES-CBC3-SHA

The following categories of ciphers are permanently restricted:

!aNULL  
!eNULL  
!EXPORT  
!LOW  
!MD5  
!DES  
!RC2  
!RC4  
!PSK  
!SSLv3

If the server is started with thessl_cert system variable set to a certificate that uses any of the preceding restricted ciphers or cipher categories, the server starts with support for encrypted connections disabled.

Connection TLS Protocol Negotiation

Connection attempts in MySQL negotiate use of the highest TLS protocol version available on both sides for which a protocol-compatible encryption cipher is available on both sides. The negotiation process depends on factors such as the SSL library used to compile the server and client, the TLS protocol and encryption cipher configuration, and which key size is used:

For a connection attempt to succeed, the server and client TLS protocol configuration must permit some protocol in common.
Similarly, the server and client encryption cipher configuration must permit some cipher in common. A given cipher may work only with particular TLS protocols, so a protocol available to the negotiation process is not chosen unless there is also a compatible cipher.
If TLSv1.3 is available, it is used if possible. (This means that server and client configuration both must permit TLSv1.3, and both must also permit some TLSv1.3-compatible encryption cipher.) Otherwise, MySQL continues through the list of available protocols, using TLSv1.2 if possible, and so forth. Negotiation proceeds from more secure protocols to less secure. Negotiation order is independent of the order in which protocols are configured. For example, negotiation order is the same regardless of whethertls_version has a value ofTLSv1,TLSv1.1,TLSv1.2,TLSv1.3 orTLSv1.3,TLSv1.2,TLSv1.1,TLSv1.
TLSv1.2 does not work with all ciphers that have a key size of 512 bits or less. To use this protocol with such a key, set the ssl_cipher system variable on the server side or use the--ssl-cipher client option to specify the cipher name explicitly:

AES128-SHA  
AES128-SHA256  
AES256-SHA  
AES256-SHA256  
CAMELLIA128-SHA  
CAMELLIA256-SHA  
DES-CBC3-SHA  
DHE-RSA-AES256-SHA  
RC4-MD5  
RC4-SHA  
SEED-SHA

For better security, use a certificate with an RSA key size of at least 2048 bits.

If the server and client do not have a permitted protocol in common, and a protocol-compatible cipher in common, the server terminates the connection request. Examples:

If the server is configured withtls_version=TLSv1.1,TLSv1.2:
- Connection attempts fail for clients invoked with--tls-version=TLSv1, and for older clients that support only TLSv1.
- Similarly, connection attempts fail for replicas configured with MASTER_TLS_VERSION = 'TLSv1', and for older replicas that support only TLSv1.
If the server is configured withtls_version=TLSv1 or is an older server that supports only TLSv1:
- Connection attempts fail for clients invoked with--tls-version=TLSv1.1,TLSv1.2.
- Similarly, connection attempts fail for replicas configured with MASTER_TLS_VERSION = 'TLSv1.1,TLSv1.2'.

MySQL permits specifying a list of protocols to support. This list is passed directly down to the underlying SSL library and is ultimately up to that library what protocols it actually enables from the supplied list. Please refer to the MySQL source code and the OpenSSLSSL_CTX_new() documentation for information about how the SSL library handles this.

Monitoring Current Client Session TLS Protocol and Cipher

To determine which encryption TLS protocol and cipher the current client session uses, check the session values of theSsl_version andSsl_cipher status variables:

mysql> SELECT * FROM performance_schema.session_status
       WHERE VARIABLE_NAME IN ('Ssl_version','Ssl_cipher');
+---------------+---------------------------+
| VARIABLE_NAME | VARIABLE_VALUE            |
+---------------+---------------------------+
| Ssl_cipher    | DHE-RSA-AES128-GCM-SHA256 |
| Ssl_version   | TLSv1.2                   |
+---------------+---------------------------+

If the connection is not encrypted, both variables have an empty value.