import re
RegexLength=re.compile(r'^\S{8,}$')
RegexDigit=re.compile(r'\d')
RegexLower=re.compile(r'[a-z]')
RegexUpper=re.compile(r'[A-Z]')
def IsStrongPW(password):
if RegexLength.search(password) == None or RegexDigit.search(password) == None or RegexUpper.search(password) == None or RegexLower.search(password) == None:
return False
else:
return True
while True:
userpw=input("please input your passord to check: \n")
if userpw == "exit":
break
else:
print(IsStrongPW(userpw))
You should also consider changing some of your rules to:
With the above improvements, and for more flexibility and readability, I would modify the regex to.
^(?=(.*[a-z]){3,})(?=(.*[A-Z]){2,})(?=(.*[0-9]){2,})(?=(.*[!@#$%^&*()\-__+.]){1,}).{8,}$
Basic Explanation
(?=(.*RULE){MIN_OCCURANCES,})
Each rule block is shown by (?=(){}). The rule and number of occurrences can then be easily specified and tested separately, before getting combined
Detailed Explanation
^ start anchor
(?=(.*[a-z]){3,}) lowercase letters. {3,} indicates that you want 3 of this group
(?=(.*[A-Z]){2,}) uppercase letters. {2,} indicates that you want 2 of this group
(?=(.*[0-9]){2,}) numbers. {2,} indicates that you want 2 of this group
(?=(.*[!@#$%^&*()\-__+.]){1,}) all the special characters in the [] fields. The ones used by regex are escaped by using the \ or the character itself. {1,} is redundant, but good practice, in case you change that to more than 1 in the future. Also keeps all the groups consistent
{8,} indicates that you want 8 or more
$ end anchor
And lastly, for testing purposes here is a robulink with the above regex
codaddict's solution works fine, but this one is a bit more efficient: (Python syntax)
password = re.compile(r"""(?#!py password Rev:20160831_2100)
# Validate password: 2 upper, 1 special, 2 digit, 1 lower, 8 chars.
^ # Anchor to start of string.
(?=(?:[^A-Z]*[A-Z]){2}) # At least two uppercase.
(?=[^!@#$&*]*[!@#$&*]) # At least one "special".
(?=(?:[^0-9]*[0-9]){2}) # At least two digit.
.{8,} # Password length is 8 or more.
$ # Anchor to end of string.
""", re.VERBOSE)
The negated character classes consume everything up to the desired character in a single step, requiring zero backtracking. (The dot star solution works just fine, but does require some backtracking.) Of course with short target strings such as passwords, this efficiency improvement will be negligible.
You can use zero-length positive look-aheads to specify each of your constraints separately:
(?=.{8,})(?=.*\p{Lu}.*\p{Lu})(?=.*[!@#$&*])(?=.*[0-9])(?=.*\p{Ll}.*\p{Ll})
If your regex engine doesn't support the \p notation and pure ASCII is enough, then you can replace \p{Lu} with [A-Z] and \p{Ll} with [a-z].
I would suggest adding
(?!.*pass|.*word|.*1234|.*qwer|.*asdf) exclude common passwords
For PHP, this works fine!
if(preg_match("/^(?=(?:[^A-Z]*[A-Z]){2})(?=(?:[^0-9]*[0-9]){2}).{8,}$/",
'CaSu4Li8')){
return true;
}else{
return fasle;
}
in this case the result is true
Thsks for @ridgerunner
Answers given above are perfect but I suggest to use multiple smaller regex rather than a big one.
Splitting the long regex have some advantages:
Generally this approach keep code easily maintainable.
Having said that, I share a piece of code that I write in Swift as example:
struct RegExp {
/**
Check password complexity
- parameter password: password to test
- parameter length: password min length
- parameter patternsToEscape: patterns that password must not contains
- parameter caseSensitivty: specify if password must conforms case sensitivity or not
- parameter numericDigits: specify if password must conforms contains numeric digits or not
- returns: boolean that describes if password is valid or not
*/
static func checkPasswordComplexity(password password: String, length: Int, patternsToEscape: [String], caseSensitivty: Bool, numericDigits: Bool) -> Bool {
if (password.length < length) {
return false
}
if caseSensitivty {
let hasUpperCase = RegExp.matchesForRegexInText("[A-Z]", text: password).count > 0
if !hasUpperCase {
return false
}
let hasLowerCase = RegExp.matchesForRegexInText("[a-z]", text: password).count > 0
if !hasLowerCase {
return false
}
}
if numericDigits {
let hasNumbers = RegExp.matchesForRegexInText("\\d", text: password).count > 0
if !hasNumbers {
return false
}
}
if patternsToEscape.count > 0 {
let passwordLowerCase = password.lowercaseString
for pattern in patternsToEscape {
let hasMatchesWithPattern = RegExp.matchesForRegexInText(pattern, text: passwordLowerCase).count > 0
if hasMatchesWithPattern {
return false
}
}
}
return true
}
static func matchesForRegexInText(regex: String, text: String) -> [String] {
do {
let regex = try NSRegularExpression(pattern: regex, options: [])
let nsString = text as NSString
let results = regex.matchesInString(text,
options: [], range: NSMakeRange(0, nsString.length))
return results.map { nsString.substringWithRange($0.range)}
} catch let error as NSError {
print("invalid regex: \(error.localizedDescription)")
return []
}
}
}
Another solution:
import re
passwordRegex = re.compile(r'''(
^(?=.*[A-Z].*[A-Z]) # at least two capital letters
(?=.*[!@#$&*]) # at least one of these special c-er
(?=.*[0-9].*[0-9]) # at least two numeric digits
(?=.*[a-z].*[a-z].*[a-z]) # at least three lower case letters
.{8,} # at least 8 total digits
$
)''', re.VERBOSE)
def userInputPasswordCheck():
print('Enter a potential password:')
while True:
m = input()
mo = passwordRegex.search(m)
if (not mo):
print('''
Your password should have at least one special charachter,
two digits, two uppercase and three lowercase charachter. Length: 8+ ch-ers.
Enter another password:''')
else:
print('Password is strong')
return
userInputPasswordCheck()
Password must meet at least 3 out of the following 4 complexity rules,
[at least 1 uppercase character (A-Z) at least 1 lowercase character (a-z) at least 1 digit (0-9) at least 1 special character — do not forget to treat space as special characters too]
at least 10 characters
at most 128 characters
not more than 2 identical characters in a row (e.g., 111 not allowed)
'^(?!.(.)\1{2}) ((?=.[a-z])(?=.[A-Z])(?=.[0-9])|(?=.[a-z])(?=.[A-Z])(?=.[^a-zA-Z0-9])|(?=.[A-Z])(?=.[0-9])(?=.[^a-zA-Z0-9])|(?=.[a-z])(?=.[0-9])(?=.*[^a-zA-Z0-9])).{10,127}$'
(?!.*(.)\1{2})
(?=.[a-z])(?=.[A-Z])(?=.*[0-9])
(?=.[a-z])(?=.[A-Z])(?=.*[^a-zA-Z0-9])
(?=.[A-Z])(?=.[0-9])(?=.*[^a-zA-Z0-9])
(?=.[a-z])(?=.[0-9])(?=.*[^a-zA-Z0-9])
.{10.127}
All of above regex unfortunately didn't worked for me. A strong password's basic rules are
So, Best Regex would be
^(?=.*[a-z])(?=.*[A-Z])(?=.*[0-9])(?=.*[!@#\$%\^&\*]).{8,}$
The above regex have minimum length of 8. You can change it from {8,} to {any_number,}
Modification in rules?
let' say you want minimum x characters small letters, y characters capital letters, z characters numbers, Total minimum length w. Then try below regex
^(?=.*[a-z]{x,})(?=.*[A-Z]{y,})(?=.*[0-9]{z,})(?=.*[!@#\$%\^&\*]).{w,}$
Note: Change x, y, z, w in regex
Edit: Updated regex answer
Edit2: Added modification
Source: Stackoverflow.com