What are the potential drawbacks of using the sleep function in PHP for adding a delay in password input validation?

Using the sleep function in PHP for adding a delay in password input validation can potentially introduce a security vulnerability known as a timing attack. This type of attack involves an attacker exploiting the delay to determine the validity of the password based on the response time. To mitigate this risk, it is recommended to use a constant-time comparison function, such as hash_equals, to compare the password hash with the user input. 

// Validate password securely using hash_equals to prevent timing attacks
function validatePassword($password, $hashedPassword) {
    // Use hash_equals to compare the password securely
    if (hash_equals($hashedPassword, crypt($password, $hashedPassword))) {
        return true;
    } else {
        return false;
    }
}

Keywords

sleep function PHP delay password input validation drawbacks

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