We have an application which encrypts the information in a column (this information is highly confidential), we are thinking to have a digital authentication for this part. Can Visual Guard support this kind of tools (to decrypt the information when it is the good user, then to manage digital authentication)?

We may need more specifications about your need to give you an accurate answer.
In the meantime, below is some information:
Visual Guard can work together with 3rd party encryption and/or authentication solutions.

For instance:
You application can call another authentication system (SmartCard, Biometrics, Token...) and then call Visual Guard with the ID of the user once authenticated. In this case, Visual Guard is independent from the authentication system. Visual Guard can then retrieve and enforce the user permissions as usual. This 3rd party authentication may happen anytime you need it: when loging in to the application, when running a sensitive operation... Your application decides when to use the 3rd party authentication and when to call Visual Guard to perform the tasks it is in charge of.
Same for encryption solutions: you may use such a system to encrypt/decrypt source code or data. You application will call Visual Guard whenever it is appropriate to call it - for instance after a data is decrypted.
You may also use Visual Guard permissions to decide when to execute the encryption or authentication solution. For instance, some user may have the required privilege to access encrypted data, in which case you activate the decryption mechanism.