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Password Validation with PHP and Regular Expressions.

Regular-Expressions are equally complicated and elegant at the exact same time. They may be made to look like someone was only hammering randomly on their keyboard. They’re also a remarkably effective and elegant solution to describing the structure of the text and fitting those structures.

They’re very handy for defining what a string should look like and as such are very great to be used in password validation. It’s essential that the password needs to be validated With safe & strength for security. So Make it difficult for password crackers. Use long passwords with letters, CAPS, numbers, and symbols. Let’s check a password validation with PHP and regular expressions. That is a straightforward and long example for beginners.

$pwd = $_POST['password '];
if( strlen($password ) < 8 ) {
$error .= "Password too short!
";
}
if( strlen($password ) > 20 ) {
$error .= "Password too long!
";
}
if( strlen($password ) < 8 ) {
$error .= "Password too short!
";
}
if( !preg_match("#[0-9]+#", $password ) ) {
$error .= "Password must include at least one number!
";
}
if( !preg_match("#[a-z]+#", $password ) ) {
$error .= "Password must include at least one letter!
";
}
if( !preg_match("#[A-Z]+#", $password ) ) {
$error .= "Password must include at least one CAPS!
";
}
if( !preg_match("#W+#", $password ) ) {
$error .= "Password must include at least one symbol!
";
}
if($error){
echo "Password validation failure(your choise is weak): $error";
} else {
echo "Your password is strong.";
}

Short example with Regex

This is the short version of that password -check with regex(lookahead / lookbehind / lookaround) using PHP’s PCRE engine.

$password = $_POST['password '];
if (preg_match("#.*^(?=.{8,20})(?=.*[a-z])(?=.*[A-Z])(?=.*[0-9])(?=.*W).*$#", $password )){
echo "Your password is strong.";
} else {
echo "Your password is not safe.";
}

You may use "d" instead of "[a-z]" and "W" instead of non-word characters, symbols. You can make a manual list of most used symbols like [#.-_,$%&!].

Remember most consumers don’t enjoy passwords with symbols, you can exclude emblem checks for. Just check letters, duration, caps, and numbers.

$password= $_POST['password'];
if (preg_match("#.*^(?=.{8,20})(?=.*[a-z])(?=.*[A-Z])(?=.*[0-9]).*$#", $password)){
echo "Your password is good.";
} else {
echo "Your password is bad.";
}

How to generate one-time passwords (OTPs) in PHP