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Overview

Caching SHA password refers to a secure authentication mechanism that combines SHA-based password hashing with temporary credential caching to optimize performance. This is most commonly implemented in MySQL 8.0+ through the caching_sha2_password plugin.

By hashing passwords with SHA-256 and caching the result in memory for the duration of a session, this method reduces the need for repeated full authentication handshakes, improving efficiency in high-frequency connection environments.

How It Works

• SHA-256 Hashing: Passwords are hashed using the SHA-256 algorithm before being stored or verified.
• Session-Based Caching: Once authenticated, credentials are cached temporarily to avoid reprocessing.
• Optimized Reconnects: Clients reconnecting within the session window benefit from faster authentication.

Checking Plugin Usage

To check which plugin is used for a MySQL user:

SELECT user, plugin FROM mysql.user;

Switching Authentication Plugin

If you need to switch to a legacy plugin for compatibility:

ALTER USER 'youruser'@'localhost' IDENTIFIED WITH mysql_native_password BY 'yourpassword';

Or set the default plugin in my.cnf:

[mysqld]
default_authentication_plugin=mysql_native_password

systemctl restart mysql

Use Cases

• Web applications with frequent database connections
• Microservices with short-lived sessions
• Environments requiring modern cryptographic standards

Security Considerations

• Pros:
  • Stronger password hashing via SHA-256
  • Improved performance for repeated logins
  • Reduced server-side CPU usage
• Cons:
  • May not be supported by older MySQL clients
  • Requires proper configuration to avoid fallback issues
  • Temporary caching may expose credentials if memory is compromised

Linux Context

In Linux systems, SHA-based password hashing is used in /etc/shadow and configured via login.defs or authconfig:

authconfig --test | grep hashing

grep ENCRYPT_METHOD /etc/login.defs

Conclusion

Caching SHA password mechanisms like caching_sha2_password offer a modern, secure, and performance-optimized approach to authentication. By combining robust hashing with session-based caching, they strike a balance between security and efficiency — especially in dynamic, high-traffic environments. For further assistance, please contact your system administrator or reach out to support@ipserverone.com.