Reports

I am using Python to demonstrate the REGEX example using Python's re regex module to validate the password. :

Included in my solution, inserted in the regex pattern are the the old_password, username, and the word "password" for different letter case variations.

The solution matches with the requirements for the password:

contains at least eight characters,
including at least one number and
includes both lower and uppercase letters and
include at least one special characters, #, ?, !.
cannot be your old password
cannot contain your username, "password", or "websitename"

PYTHON CODE:

import re

old_password = "Matilda#43555"

// # Collect username and password (defaults "matilda55577" and "HelloSunshine!456" respectively):
username = input("Username: ") or "matilda55577"
new_password = input("Password: ") or "HelloSunshine!456"

// # Insert username and password in the regex pattern: 
pattern = f"^(?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[#?!#@^*~+])(?!.*[pP][aA][sS][sS][wW][oO][rR][dD])(?!.*\.\w)(?!.*{username})(?!{old_password}$)" + ".{8,}$"
print(pattern)

pattern_re = re.compile(pattern)

for item in test_password_list: 
    print(item, end=": ")
    if pattern_re.match(item) == None:
        print("(---NOT VALID)")
    else:
        print("(---VALID)")

NOTES REGEX PATTERN:

pattern = f"^(?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[#?!#@^*~+])(?!.*[pP][aA][sS][sS][wW][oO][rR][dD])(?!.*\.\w)(?!.*{username})(?!{old_password}$)" + ".{8,}$"

ELEMENTS:

f("...{username}{password}") In Python, we can use the f-string and {variable_name_here} to enter the username and old_password values in the pattern.
^...$ Pattern must match from beginning ^ to end $.
(?=...) Positive lookahead is successful if can match to the right. Will not consume characters.
(?!...) Negative lookahead is successful if can NOT match to the right. Will not consume characters.
. Dot (.) special character. Matches all characters (except newline character \n unless single line flag is on)
.* Matches 0 or more characters, as many as possible to make a match (greedy).
\d Matches a number from zero to 9.
[...] Character class. Matches any one character listed inside the character class.
[a-z] Range of letters FROM a - z TO. Matches one lower case letter.
[A-Z] Range of letters FROM A - Z TO. Matches one upper case letter.
[#?!#@^*~+] Matches any one character listed in the character class, in this case matches one of "#?!#@^*~+".

PATTERN STATEMENTS:

Between the beginning ^ and the end of $ string:
From the beginning of the string:
(?=.*\d) Lookahead and make sure there is at least one number.
(?=.*[a-z]) Lookahead and make sure there is at least one lower case letter.
(?=.*[A-Z]) Lookahead and make sure there is at least one upper case letter.
(?=.*[#?!#@^*~+]) Lookahead and make sure there is at least one of these characters # ? ! # @ ^ * ~ +.
(?!.*[pP][aA][sS][sS][wW][oO][rR][dD]) Negative lookahead to and make sure that the word "password" is not present in any combination of upper and lower case letters.
(?!.*\.\w) Negative lookahead to make sure that there are no literal dots/periods (.) followed by a letter (rules out possible email or url)
(?!.*{username}) Fill in username. Negative lookahead to make sure that the username is not any part of the string.
(?!{old_password}$) Fill in old_password. Negative lookahead to make sure that the new_password does NOT match the old_password exactly. Note $ says it has reached the end of string.
.{8,} If all preceding lookaheads match, proceed to capture 8 or more characters. If less than 8 characters. No match, i.e. invalid new password.
$ End of string. If you get here, you have a valid password.

REGEX DEMO: https://regex101.com/r/XlyJNL/2

LIST OF TEST PASSWORDS:


test_password_list = [
new_password, 
old_password, 
username,
"Mother#234!",
"aaahelma!345",
"aaahElma!345",
"oldWorld#2222",
"77#elloYello!!!",
"Matilda#43555555",
"111matilda55577OK"
"1123444A!!!!!!!!",
"1123444A!!!!!Park!!",
"aaapasSword123#!KC",
"pASsWORd123#"
"4Matilda#43555234GGG",
"matilda55577!EFR444",
"maTmatilda55577!EFR444",
"hello.www.com.Park1!.com.youtube.com",
"https://stackoverflow.com/question/1234A!",
"ITs!stackoverflow123.com",
"ToSh4!",
"To2!",
"2!sH1",
"[email protected]",
"Matilda#43555",
"Matilda#435555"
]

RESULT:

Username:
Password:

^(?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?=.*[#?!#@^*~+])(?!.*[pP][aA][sS][sS][wW][oO][rR][dD])(?!.*\.\w)(?!.*matilda55577)(?!Matilda#43555$).{8,}$

HelloSunshine!456: (---VALID)
Matilda#43555: (---NOT VALID)
matilda55577: (---NOT VALID)
Mother#234!: (---VALID)
aaahelma!345: (---NOT VALID)
aaahElma!345: (---VALID)
oldWorld#2222: (---VALID)
77#elloYello!!!: (---VALID)
Matilda#43555555: (---VALID)
111matilda55577OK1123444A!!!!!!!!: (---NOT VALID)
1123444A!!!!!Park!!: (---VALID)
aaapasSword123#!KC: (---NOT VALID)
pASsWORd123#4Matilda#43555234GGG: (---NOT VALID)
matilda55577!EFR444: (---NOT VALID)
maTmatilda55577!EFR444: (---NOT VALID)
hello.www.com.Park1!.com.youtube.com: (---NOT VALID)
https://stackoverflow.com/question/1234A!: (---NOT VALID)
ITs!stackoverflow123.com: (---NOT VALID)
ToSh4!: (---NOT VALID)
To2!: (---NOT VALID)
2!sH1: (---NOT VALID)
[email protected]: (---NOT VALID)
Matilda#43555: (---NOT VALID)
Matilda#435555: (---VALID)

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