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Encrypting passwords

From: PHP with MySQL Essential Training

Video: Encrypting passwords

In this movie, we'll learn about encrypting passwords. Hashing is the term for the process of taking a string of data and apply a mathematical function to it to produce a unique string of output. Which is known as a hash. Hashing is often used for encryption but that's not its only use. For example, it can be used to create unique identifiers or to quickly determine if a large amount of data has changed. But what we're interesting in using it for is password hashing. That is, applying an algorithm to a password, to generate an encrypted string. Knowing an encrypting hash won't give away the password and the original password can't be reverse engineered even with lots of computing power.

Encrypting passwords

In this movie, we'll learn about encrypting passwords. Hashing is the term for the process of taking a string of data and apply a mathematical function to it to produce a unique string of output. Which is known as a hash. Hashing is often used for encryption but that's not its only use. For example, it can be used to create unique identifiers or to quickly determine if a large amount of data has changed. But what we're interesting in using it for is password hashing. That is, applying an algorithm to a password, to generate an encrypted string. Knowing an encrypting hash won't give away the password and the original password can't be reverse engineered even with lots of computing power.

And the hash that it generates for each password will be unique, so that it can only be recreated by using the same password with the same hashing algorithm. In short, the only way to have a password match will be to know the original password and that's what we want. Now the most important rule about passwords is never ever, ever store passwords in the database as plain text, always encrypt them. If they're in plain text, then anyone who gains access to your database will have every user's password. And its not just hackers on the outside that you have to be concerned about.

Authorized users are a concern too, any site administrator or employee or person with database access, has the potential to know all user passwords. A data backup your ISP makes for you or hard drive that doesn't get wiped completely before being sold or discarded. Both have serious potential for leaking passwords. And these are not just theoretical examples, they've happened. It's not just your site security that you put at risk, if you don't encrypt your passwords. Many users use the same username and passwords on multiple sites. If a user uses the same password on your site as for their bank account, you don't want to be the one providing a hole in the bank security.

So please, do it for all of us other site developers, if not for yourself. Make sure that you always encrypt passwords before storing them. Now, we're not just going to be encrypting them, we're going to be using one-way encryption. It won't be possible for anyone to get the original password out of the encrypted string, including us. It works because the principle is the same inputs to the same hashing algorithm will always result in the same output. So we'll take the password, we'll encrypt it, and then we'll store the result in the database. Then when a user comes to our site and tries to log in, we'll take their attempted password, we'll pass it to the same hashing algorithm.

And then we'll see if the output matches what we have stored. If the output is the same, then we know that the input was correct. If the output's different, we'll know that the input wasn't. Now there are dozens of hashing algorithms out there. Before we pick one, we need to first consider how secure do we need our site to be? I mean, I can keep $100 in my house, just lock the doors, and feel pretty secure that no one's going to take it. But if I have $100 million, then I'd probably be out shopping for some pretty fancy security systems. In the same way, encryption level is specific to each developer. I'll provide a good standard set of best practices that will meet the needs of 99% of you.

The other 1% typically work for organizations, like financial institutions or government agencies. And if that's you, then your organization probably has published guidelines for what additional encryption or security you'll need. Now out of the dozens of hashing algorithms, all for different uses not all of them are suitable for password hashing. Here are a few popular and respected choices we have MD5, SHA-1, SHA-2, Whirlpool, Tiger, AES and Blowfish. Now MD5 used to be a good choice and lots of people used it, but it's not recommended anymore.

A security flaw has been discovered in it. The weakness is not simple to exploit, but it is enough to make it less than ideal, especially since we have other candidates. SHA-1 is a good choice. There is a theory about a possible weakness in it, but no exploit has actually been found. It's still just a theory. So, it does still remain secure enough for our purposes. But we also have SHA-2, which is a stronger version of SHA-1. It comes in two versions, SHA 256, and SHA 512, neither of which has any known weaknesses yet.

I've heard that the US government is moving to SHA-2 as a minimum level of encryption. Whirlpool, Tiger, and AES are all three other very popular choices that offer very strong security, any of them would work great. However, we're going to go with the last one, which is Blowfish. Blowfish offers a high-level of security, it's in the public domain, there's no patent, so it's free to use, which is part of why it became very popular. And it's included with PHP 5.3 and later, so we have it built in and ready to go. And then, the other attribute that makes it a great choice for password security is the fact that it's slow. Now you may be thinking, wait a minute, slow? Don't I want my code to run as fast as possible? I don't want my website to be slow. Well, here's a case where you'd do, slower is better. And that's because if someone is coming to your site. And they're running a computer program that's just trying every password under the sun, just to see if they can brute force their way in, and just guess passwords.

You want that process to be as slow as possible for them. You don't want them to be able to try thousands of passwords per minute. You wanted to slow it down so they can only try thousands of passwords per hour. Where as they might have been able before to break into your site in 48 hours time, now it can slow them down to point where it takes them 10 or 12 years for them to do it. But it's not so slow that it's going to impact users. To our users there'll just be a brief pause while it compares and then it will come back with the results. And that pause is okay, it's perfectly acceptable. But to a hacker whose trying to run thousands and thousands of attempts per hour, it'll throw a real wrench in their plans.

So, slow in this case is a good thing. Now that we know which algorithm we're going to be using, let's talk a little about algorithms in PHP. It's a little bit of a history lesson. In PHP3 we had md5, and for a long time, that's what a lot of people used. It was a great algorithm for a long time, until people started finding problems with it. SHA-1 then became very popular. That came out in 4.3, and a lot of people used that for a while. Notice that the functions are named after the algorithm. But there's so many algorithms out there, there's dozens. And we don't really want to have a function for each and every once. So instead, in PHP 5.1.2, we got a new function called hash. And you tell hash what algorithm you want to use and then the password. So, we don't have to have a function for every single one under the sun. Now hash is very fast and it supports many algorithms. You want a full list of those algorithms, there's another function called hash_algos that'll return a list of them to you. But notice that I said it's very fast.

It's suitable when we want to make a hash of something for other purposes besides passwords. When we want to do it with passwords, we're going to use crypt. Crypt is introduced in PHP 5.3 and it's slow. It only supports six algorithms, one of which is Blowfish. And even the algorithms like MD5 that it uses aren't identical to what hash uses. What I mean is, hash does an MD5 process on something once, whereas crypt might do the MD5 on it seven times. That's part of what makes it slower.

But the end result that comes back at the end, is not going to be the same. It may not generate the same hash if you use hash or if you use crypt. They have different purposes. They're using a same hash, but in different ways. Now, notice that whereas in hash, we pass in the algorithm we want to use, in crypt, we don't provide that. There's not a space for that. Instead there's this thing called salt. We'll talk about that in the next movie. We'll talk about what salt is, and in that salt, we're going to also tell it what algorithm crypt should be using.

Show transcript

This video is part of

Image for PHP with MySQL Essential Training
PHP with MySQL Essential Training

131 video lessons · 32795 viewers

Kevin Skoglund
Author

 
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  1. 4m 8s
    1. Welcome
      1m 0s
    2. Using the exercise files
      3m 8s
  2. 15m 6s
    1. What is PHP?
      3m 52s
    2. The history of PHP
      2m 51s
    3. Why choose PHP?
      4m 10s
    4. Installation overview
      4m 13s
  3. 54m 53s
    1. Overview
      2m 33s
    2. Working with Apache Web Server
      6m 56s
    3. Changing the document root
      7m 24s
    4. Enabling PHP
      6m 16s
    5. Upgrading PHP
      3m 30s
    6. Configuring PHP
      10m 3s
    7. Installing MySQL
      5m 46s
    8. Configuring MySQL
      7m 24s
    9. Text editor
      5m 1s
  4. 31m 25s
    1. Overview
      3m 27s
    2. Installing WampServer
      5m 46s
    3. Finding the document root
      2m 24s
    4. Configuring PHP
      8m 12s
    5. Configuring MySQL
      5m 45s
    6. Text editor
      5m 51s
  5. 19m 12s
    1. Embedding PHP code on a page
      6m 43s
    2. Outputting dynamic text
      5m 55s
    3. The operational trail
      2m 27s
    4. Inserting code comments
      4m 7s
  6. 1h 18m
    1. Variables
      7m 50s
    2. Strings
      4m 38s
    3. String functions
      8m 54s
    4. Numbers part one: Integers
      6m 27s
    5. Numbers part two: Floating points
      5m 25s
    6. Arrays
      10m 0s
    7. Associative arrays
      6m 37s
    8. Array functions
      6m 33s
    9. Booleans
      3m 50s
    10. NULL and empty
      5m 15s
    11. Type juggling and casting
      8m 27s
    12. Constants
      4m 43s
  7. 27m 37s
    1. If statements
      6m 0s
    2. Else and elseif statements
      4m 16s
    3. Logical operators
      7m 30s
    4. Switch statements
      9m 51s
  8. 42m 15s
    1. While loops
      8m 41s
    2. For loops
      5m 59s
    3. Foreach loops
      8m 16s
    4. Continue
      8m 28s
    5. Break
      4m 8s
    6. Understanding array pointers
      6m 43s
  9. 37m 25s
    1. Defining functions
      8m 25s
    2. Function arguments
      5m 32s
    3. Returning values from a function
      7m 33s
    4. Multiple return values
      4m 53s
    5. Scope and global variables
      6m 2s
    6. Setting default argument values
      5m 0s
  10. 20m 18s
    1. Common problems
      3m 47s
    2. Warnings and errors
      8m 36s
    3. Debugging and troubleshooting
      7m 55s
  11. 57m 57s
    1. Links and URLs
      5m 33s
    2. Using GET values
      5m 35s
    3. Encoding GET values
      8m 41s
    4. Encoding for HTML
      9m 26s
    5. Including and requiring files
      7m 40s
    6. Modifying headers
      6m 45s
    7. Page redirection
      6m 43s
    8. Output buffering
      7m 34s
  12. 1h 3m
    1. Building forms
      7m 28s
    2. Detecting form submissions
      5m 59s
    3. Single-page form processing
      7m 57s
    4. Validating form values
      10m 40s
    5. Problems with validation logic
      9m 54s
    6. Displaying validation errors
      7m 23s
    7. Custom validation functions
      6m 28s
    8. Single-page form with validations
      7m 25s
  13. 28m 5s
    1. Working with cookies
      2m 49s
    2. Setting cookie values
      5m 55s
    3. Reading cookie values
      6m 1s
    4. Unsetting cookie values
      4m 51s
    5. Working with sessions
      8m 29s
  14. 48m 39s
    1. MySQL introduction
      6m 43s
    2. Creating a database
      7m 41s
    3. Creating a database table
      7m 42s
    4. CRUD in MySQL
      5m 48s
    5. Populating a MySQL database
      7m 32s
    6. Relational database tables
      6m 40s
    7. Populating the relational table
      6m 33s
  15. 56m 4s
    1. Database APIs in PHP
      4m 51s
    2. Connecting to MySQL with PHP
      7m 45s
    3. Retrieving data from MySQL
      8m 47s
    4. Working with retrieved data
      6m 12s
    5. Creating records with PHP
      6m 58s
    6. Updating and deleting records with PHP
      9m 6s
    7. SQL injection
      3m 5s
    8. Escaping strings for MySQL
      6m 45s
    9. Introducing prepared statements
      2m 35s
  16. 35m 58s
    1. Blueprinting the application
      7m 19s
    2. Building the CMS database
      5m 14s
    3. Establishing your work area
      4m 38s
    4. Creating and styling the first page
      4m 22s
    5. Making page assets reusable
      6m 36s
    6. Connecting the application to the database
      7m 49s
  17. 32m 49s
    1. Adding pages to the navigation subjects
      5m 58s
    2. Refactoring the navigation
      6m 7s
    3. Selecting pages from the navigation
      6m 2s
    4. Highlighting the current page
      5m 26s
    5. Moving the navigation to a function
      9m 16s
  18. 1h 45m
    1. Finding a subject in the database
      9m 48s
    2. Refactoring the page selection
      10m 52s
    3. Creating a new subject form
      6m 55s
    4. Processing form values and adding subjects
      11m 20s
    5. Passing data in the session
      9m 16s
    6. Validating form values
      9m 40s
    7. Creating an edit subject form
      8m 30s
    8. Using single-page submission
      7m 44s
    9. Deleting a subject
      9m 44s
    10. Cleaning up
      10m 37s
    11. Assignment: Pages CRUD
      4m 30s
    12. Assignment results: Pages CRUD
      6m 10s
  19. 39m 26s
    1. The public appearance
      8m 52s
    2. Using a context for conditional code
      11m 37s
    3. Adding a default subject behavior
      6m 9s
    4. The public content area
      5m 51s
    5. Protecting page visibility
      6m 57s
  20. 1h 3m
    1. User authentication overview
      4m 3s
    2. Admin CRUD
      8m 41s
    3. Encrypting passwords
      7m 26s
    4. Salting passwords
      5m 42s
    5. Adding password encryption to CMS
      11m 54s
    6. New PHP password functions
      3m 13s
    7. Creating a login system
      11m 28s
    8. Checking for authorization
      5m 48s
    9. Creating a logout page
      5m 40s
  21. 2m 4s
    1. Next steps
      2m 4s

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