SYDO is a tool that aims to protect data stored in SQL databases from threats like SQL injection, server hijacking, and data theft. It works by encrypting data using AES 128 keys that are stored remotely in a SYDO Hash Center. When a SQL query is made, SYDO generates an identification key stub to identify the query in a way that prevents SQL injection. Data is then encrypted and decrypted through a RESTful encrypted API between the client and the SYDO Hash Center. The tool provides features like support for multiple SQL interfaces and databases, API statistics, and management of multiple websites through the centralized Hash Center.