Even if you have a number of different hashing functions, each used one, throughout the code, it would make sense to place all of the hashing functions into nam

Even if you have a number of different hashing functions, each used one, throughout the code, it would make sense to place all of the hashing functions into namespace next to each other. That way you can reuse if needed and checking for security problems is easier. (It can also make the code more readable because the details of the hashing are abstracted behind a method.)