What is the proper way to sanitize a password? [duplicate]

Question

How can I sanitize a string that receives a hash+random salt?

I can remove the white spaces, check the length and use mysqli_real_escape_string, but is it sufficient? The filter_var is really useful but it can't help in this case, right?

Answer 1

If you are going to put the variable in an SQL query, then you either need to call mysqli_read_escape_string or (even better!) use prepared statements.

There's no other sanitization you need to do. However, if the value will be coming from freeform user input (e.g. a text box instead of a drop down menu) then you may also want to trim whitespace and lowercase it as a courtesy to the user (to correct accidental mistakes they might make). It really depends on the application.