A Guide to Password Hashing

What is Password Hashing

Passwords are something that pretty much everyone has! And, under the Data Protection Act of 1998(UK), all passwords must be kept safe and secure. If a hacker gains access to passwords, then you are responsible for not keeping them secure.

So, what's the solution?

Password hashing is converting passwords to a string of characters that can't be turned back into the password. Think of it like this:.

      
password = 'hello world' # password is set
hashword = hash(password) # password gets hashed
password != unhash(password) # password can't be unhashed with our knowledge of maths

Example

I've written a Python script to hash a string:

      
from werkzeug.security import generate_password_hash # pip install werkzeug

password = 'hello world'
hashword = generate_password_hash(password, 'sha256')

print(hashword)

Output: ha256$Wz1CerC5MmrinjlW$56f1b796758634f1c17640dcfbc1905938a20caa3434c0ec8ca09fd8cdc9669d

So, what does this do?

Well, werkzeug is a python package developed by palletsprojects, the creators of the Flask framework. werkzeug means tools in German.

Anway, werkzeug has a security file with a function called generate_password_hash. This hashes the password that you pass to it. You also need to pass a hashing method to it. I used sha256 which is one of the most popular hashing methods.

Once hashed, the password becomes a long string of letters and numbers. The ha256 at the beginning of the hashed password defines the hashing method that was used.

Repl: @DillonB07/pseudo-randomNumbersDemo

Benefits

The benefits of hashing a password are that:

You can't find the original password with our knowledge of maths.
The original password isn't stored in the database, so data is useless to hackers
More security for open source websites!

How to hash

As I mentioned earlier, werkzeug is a great python module for hashing!

      
from werkzeug.security import generate_password_hash, check_password_hash

generate_password_hash hashes the password that you give it.
check_password_hash can be used to check if the inputted password is the same as the hashed password. More on this later.

You might think that you could hash the inputted password and compare it to the password in the database, but you can't because it gets hashed differently. This is demonstrated here:

      
password = 'hello world'
hashword = generate_password_hash(password, 'sha256')
print(f'1: {hashword}')

password1 = 'hello world'
hashword1 = generate_password_hash(password1, 'sha256')
print(f'2: {hashword1}')

Output:
1: sha256$hoRRG7sXinkSjcBY$5ede7c11b9658239e9319f97ea2da55ef5044e87b5311bce3c230ce155f31a35
2: sha256$iDw7mL3jt6Jyf7D5$1a8e1f5cacf6e3bb33dd59548c05e515fff4d59354a63463025858a3f95286aa

Now, let's check if these passwords are the same:

      
from werkzeug.security import generate_password_hash, check_password_hash

password = 'hello world'
hashword = generate_password_hash(password, 'sha256')
print(f'1: {hashword}')

password1 = 'hello world'
hashword1 = generate_password_hash(password1, 'sha256')
print(f'2: {hashword1}')

checked = check_password_hash(hashword, password1)
print(checked)

Output:
1: sha256$0pMTuRIPZAgIY9rj$7c0f65d63608f483d4e0c8713b0ec7a725b8db102cd01a22a5dcd5dd5e278a5b
2: sha256$HkBW2kGoKAobLNbH$6b4e6e091ea619e3e3a62a998da91f651dc753e7794291987e648d8c22b90c87
True

To use check_password_hash, you need to pass the hashed password, and the raw password to check it with. If the passwords are the same, check_password_hash will return True. If it isn't, you'll get False.

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