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authenticationauthorizationpassword-encryptionlogonserver

The proper way of implementing user login system

I want to make a user login system for the purpose of learning. I have several questions.

I did some research and found that the proper way of implementing a user login system is to store the user name/id and the encrypted/hashed version of the password in the database. When a user logs in, the password is encrypted client side (MD5, SHA-1 etc.) and sent to the server where it is compared with the one in database. If they match, the user log in successfully.

This implementation prevents DBAs or programmers seeing the cleartext of the password in the database. It can also prevent hackers intercepting the real password in transit.

Here is where I'm confused:

  1. What if the hackers know the hash/encrypted version of password (by hacking the database) or DBAs, programmers get the hashed version of the password by just simply reading the text in the database. They could then easily make a program that sends this hashed version of the password to the server allowing them to successfully log in. If they can do that, encrypting the password doesn't seem very useful. I think I misunderstanding something here.

  2. Is this (the way I described above) the most popular way to implement user login functionality? Does it follow current best practices? Do I have to do everything manually or does some database have the built-in ability to do the same thing? Is there a most common way/method of doing this for a website or a web app? If so, please provide me with details.

  3. My former company used couchDB to store user login info including passwords. They did not do too much with the encryption side of things. They said couchDB will automatically encrypt the password and store it in the documents. I am not sure if this is a safe way. If so, then it is pretty convenient for programmers because it saves lots of work.

  4. Is this way (point 3) secure enough for normal use? Do other database system such as mySQL have this kind of ability that can do the same thing? If so, does it mean that using mySQL built-in method is secure enough?

I am not looking for a very super secure way of implementing user login functionality. I am rather looking for a way that is popular, easy-to-implement, proper, secure enough for most web applications. Please give me some advice. Details provided will be really appreciated.

Solution

  • A few clarifications:

    1. Don't use MD5. It's considered broken. Use SHA but I'd recommend something a little better than SHA1. - https://en.wikipedia.org/wiki/MD5
    2. You don't mention anything about salting the password. This is essential to protect against Rainbow tables. - https://en.wikipedia.org/wiki/Rainbow_tables
    3. The idea of salting/hashing passwords isn't really to protect your own application. It's because most users have a few passwords that they use for a multitude of sites. Hashing/salting prevents anyone who gains access to your database from learning what these passwords are and using them to log into their banking application or something similar. Once someone gains direct access to the database your application's security has already been fully compromised. - http://nakedsecurity.sophos.com/2013/04/23/users-same-password-most-websites/
    4. Don't use the database's built in security to handle your logins. It's hacky and gives them way more application access than they should have. Use a table.
    5. You don't mention anything about SSL. Even a well designed authentication system is useless if the passwords are sent across the wire in plain text. There are other approaches like Challenge/Response but unfortunately the password still has to be sent in plain text to the server when the user registers or changes their password. SSL is the best way to prevent this.