There are several requirements that a password validator should meet in order to be compliant with various standards such as GDPR, ISO 27001/27002, PCI DSS, and NIST 800-53. Here are some general guidelines for creating a strong and compliant password:

1. Length: A password should be at least 8 characters long. Some standards may require longer passwords, up to 12 or 16 characters.
2. Complexity: A password should contain a mix of uppercase and lowercase letters, numbers, and special characters. Avoid using easily guessable information such as your name, address, or common words.
3. Uniqueness: Each password should be unique and not used for any other accounts.
4. Change frequency: It is recommended to change passwords at regular intervals, such as every 90 days or every year. Some standards may require more frequent changes.
5. Storage: Passwords should be stored in a secure, encrypted format. They should not be written down or shared with anyone.
6. Multi-factor authentication: It is recommended to use multi-factor authentication (MFA) in addition to a password, such as a code sent to your phone or a biometric factor like a fingerprint.

It’s important to note that these are just general guidelines and specific requirements may vary depending on the standard or regulation in question. It’s always a good idea to consult the specific requirements of the standard or regulation you are following to ensure compliance of your password validator.

Sample Python Password validator as per the requirements of GDPR, ISO 27001/27002, PCI DSS, and NIST 800-53

Here is a simple Python function that can be used to check if a password meets certain requirements for complexity and length:

import re

def check_password_strength(password):
    """
    Check the strength of a password by verifying that it meets certain requirements.
    """
    # Check password length
    if len(password) < 8:
        return False

    # Check for at least one uppercase letter
    if not re.search(r'[A-Z]', password):
        return False

    # Check for at least one lowercase letter
    if not re.search(r'[a-z]', password):
        return False

    # Check for at least one digit
    if not re.search(r'\d', password):
        return False

    # Check for at least one special character
    if not re.search(r'[!@#$%^&*()_+-=[]{};:\'",.<>/?\\|]', password):
        return False

    # If all checks pass, return True
    return True

To use this function, you can simply call it and pass in the password you want to check as an argument. For example:

password = "MyP@ssw0rd"

if check_password_strength(password):
    print("Password is strong and meets requirements")
else:
    print("Password is weak or does not meet requirements")

This function checks that the password is at least 8 characters long, contains at least one uppercase letter, one lowercase letter, one digit, and one special character. You can modify the requirements to meet the specific standards or regulations you are following.