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Password regex Python
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Password regex Python

Password

Password regular expression can be used to verify that a password provided is strong enough to provide better protection against bot brute force attacks. This method, however, does not guarantee that a password will have enough entropy to be completely safe.

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Strong password regex

The regular expression below cheks that a password:

  • Has minimum 8 characters in length. Adjust it by modifying {8,}
  • At least one uppercase English letter. You can remove this condition by removing (?=.*?[A-Z])
  • At least one lowercase English letter.  You can remove this condition by removing (?=.*?[a-z])
  • At least one digit. You can remove this condition by removing (?=.*?[0-9])
  • At least one special character,  You can remove this condition by removing (?=.*?[#?!@$%^&*-])
"^(?=.*?[A-Z])(?=.*?[a-z])(?=.*?[0-9])(?=.*?[#?!@$%^&*-]).{8,}$"

Test it!
/^(?=.*?[A-Z])(?=.*?[a-z])(?=.*?[0-9])(?=.*?[#?!@$%^&*-]).{8,}$/

True

False

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Example code in Python:

import re

# Validate strong password
password_pattern = "^(?=.*?[A-Z])(?=.*?[a-z])(?=.*?[0-9])(?=.*?[#?!@$%^&*-]).{8,}$"
re.match(password_pattern, 'secret') # Returns None
re.match(password_pattern, '-Secr3t.') # Returns Match object

Test it!

True

False

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Test it!

True

False

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Notes on password regex validation

While this regex validation is better than nothing, in situations when additional security is needed you should also check the password entered for a set of commonly used passwords like:

  • .Qwerty1
  • !Q1w2e3r4
  • etc

One good list can be found here.