Authentication plugin caching sha2 password reported error authentication requires secure connection

• sha256_password: Implements basic SHA-256 authentication.

• caching_sha2_password: Implements SHA-256 authentication (like sha256_password), but uses caching on the server side for better performance and has additional features for wider applicability. (In MySQL 5.7, caching_sha2_password is implemented only on the client side, as described later in this section.)

Important

In MySQL 5.7, the default authentication plugin is mysql_native_password. As of MySQL 8.0, the default authentication plugin is changed to caching_sha2_password. To enable MySQL 5.7 clients to connect to 8.0 and higher servers using accounts that authenticate with caching_sha2_password, the MySQL 5.7 client library and client programs support the caching_sha2_password client-side authentication plugin. This improves MySQL 5.7 client connect-capability compatibility with respect to MySQL 8.0 and higher servers, despite the differences in default authentication plugin.

Limiting caching_sha2_password support in MySQL 5.7 to the client-side plugin in the client library has these implications compared to MySQL 8.0:

In addition, there is no support for MySQL 5.7 replication slaves to connect to MySQL 8.0 replication masters using accounts that authenticate with caching_sha2_password. That would involve a master replicating to a slave with a version number lower than the master version, whereas masters normally replicate to slaves having a version equal to or higher than the master version.

Important

To connect to a MySQL 8.0 or higher server using an account that authenticates with the caching_sha2_password plugin, you must use either a secure connection or an unencrypted connection that supports password exchange using an RSA key pair, as described later in this section. Either way, the caching_sha2_password plugin uses MySQL’s encryption capabilities. See Section 6.3, “Using Encrypted Connections”.

Note

In the name sha256_password, “sha256” refers to the 256-bit digest length the plugin uses for encryption. In the name caching_sha2_password, “sha2” refers more generally to the SHA-2 class of encryption algorithms, of which 256-bit encryption is one instance. The latter name choice leaves room for future expansion of possible digest lengths without changing the plugin name.

• On the server side, an in-memory cache enables faster reauthentication of users who have connected previously when they connect again. (This server-side behavior is implemented only in MySQL 8.0 and higher.)

• Support is provided for client connections that use the Unix socket-file and shared-memory protocols.

Table 6.10 Plugin and Library Names for SHA-2 Authentication

• Installing SHA-2 Pluggable Authentication

• Using SHA-2 Pluggable Authentication

• Cache Operation for SHA-2 Pluggable Authentication

In MySQL 5.7, the caching_sha2_password plugin exists in client form. The client-side plugin is built into the libmysqlclient client library and is available to any program linked against libmysqlclient.

In MySQL 5.7, the caching_sha2_password client-side plugin enables connecting to MySQL 8.0 or higher servers using accounts that authenticate with the caching_sha2_password server-side plugin. The discussion here assumes that an account named 'sha2user'@'localhost' exists on the MySQL 8.0 or higher server. For example, the following statement creates such an account, where password is the desired account password:

CREATE USER 'sha2user'@'localhost'
IDENTIFIED WITH caching_sha2_password BY 'password';

caching_sha2_password supports connections over secure transport. caching_sha2_password also supports encrypted password exchange using RSA over unencrypted connections if these conditions are satisfied:

RSA support has these characteristics, where all aspects that pertain to the server side require a MySQL 8.0 or higher server:

For clients that use the caching_sha2_password plugin, passwords are never exposed as cleartext when connecting to the MySQL 8.0 or higher server. How password transmission occurs depends on whether a secure connection or RSA encryption is used:

As mentioned previously, RSA password encryption is available only if MySQL 5.7 was compiled using OpenSSL. The implication for clients from MySQL 5.7 distributions compiled using yaSSL is that, to use SHA-2 passwords, clients must use an encrypted connection to access the server. See Section 6.3.1, “Configuring MySQL to Use Encrypted Connections”.

Assuming that MySQL 5.7 has been compiled using OpenSSL, use the following procedure to enable use of an RSA key pair for password exchange during the client connection process.

After the server has been configured with the RSA key files, accounts that authenticate with the caching_sha2_password plugin have the option of using those key files to connect to the server. As mentioned previously, such accounts can use either a secure connection (in which case RSA is not used) or an unencrypted connection that performs password exchange using RSA. Suppose that an unencrypted connection is used. For example:

shell> mysql --ssl-mode=DISABLED -u sha2user -p
Enter password: password

For this connection attempt by sha2user, the server determines that caching_sha2_password is the appropriate authentication plugin and invokes it (because that was the plugin specified at CREATE USER time). The plugin finds that the connection is not encrypted and thus requires the password to be transmitted using RSA encryption. However, the server does not send the public key to the client, and the client provided no public key, so it cannot encrypt the password and the connection fails:

ERROR 2061 (HY000): Authentication plugin 'caching_sha2_password'
reported error: Authentication requires secure connection.

To request the RSA public key from the server, specify the --get-server-public-key option:

shell> mysql --ssl-mode=DISABLED -u sha2user -p --get-server-public-key
Enter password: password

In this case, the server sends the RSA public key to the client, which uses it to encrypt the password and returns the result to the server. The plugin uses the RSA private key on the server side to decrypt the password and accepts or rejects the connection based on whether the password is correct.

Alternatively, if the client has a file containing a local copy of the RSA public key required by the server, it can specify the file using the --server-public-key-path option:

shell> mysql --ssl-mode=DISABLED -u sha2user -p --server-public-key-path=file_name
Enter password: password

In this case, the client uses the public key to encrypt the password and returns the result to the server. The plugin uses the RSA private key on the server side to decrypt the password and accepts or rejects the connection based on whether the password is correct.

The public key value in the file named by the --server-public-key-path option should be the same as the key value in the server-side file named by the caching_sha2_password_public_key_path system variable. If the key file contains a valid public key value but the value is incorrect, an access-denied error occurs. If the key file does not contain a valid public key, the client program cannot use it.

Client users can obtain the RSA public key two ways:

On the server side, the caching_sha2_password plugin uses an in-memory cache for faster authentication of clients who have connected previously. For MySQL 5.7, which supports only the caching_sha2_password client-side plugin, this server-side caching thus takes place on the MySQL 8.0 or higher server to which you connect using MySQL 5.7 clients. For information about cache operation, see Cache Operation for SHA-2 Pluggable Authentication , in MySQL 8.0 Reference Manual .