Login Problems with PHP

Question

I can't fix it yet and I don't know what's the problem is. I'm using it on xampp. I changed in my register.php the hash to sha256. Now if I'm trying to login with that's password and username which I registered, it says the username and password is wrong.

That's my login.php

 if(empty($username_err) && empty($password_err)){
    // Prepare a select statement
    $sql = "SELECT id, username, password FROM users WHERE username = ?";
    
    if($stmt = mysqli_prepare($link, $sql)){
        // Bind variables to the prepared statement as parameters
        mysqli_stmt_bind_param($stmt, "s", $param_username);
        
        // Set parameters
        $param_username = $username;
        
        // Attempt to execute the prepared statement
        if(mysqli_stmt_execute($stmt)){
            // Store result
            mysqli_stmt_store_result($stmt);
            
            // Check if username exists, if yes then verify password
            if(mysqli_stmt_num_rows($stmt) == 1){                    
                // Bind result variables
                mysqli_stmt_bind_result($stmt, $id, $username, $hashed_password);
                if(mysqli_stmt_fetch($stmt)){
                    if(password_verify($password, $hashed_password)){
                        // Password is correct, so start a new session
                        session_start();
                        
                        // Store data in session variables
                        $_SESSION["loggedin"] = true;
                        $_SESSION["id"] = $id;
                        $_SESSION["username"] = $username;                            
                        
                        // Redirect user to welcome page
                        header("location: welcome.php");
                    } else{
                        // Password is not valid, display a generic error message
                        $login_err = "Invalid username or password.";
                    }
                }
            } else{
                // Username doesn't exist, display a generic error message
                $login_err = "Invalid username or password.";
            }
        } else{
            echo "Oops! Something went wrong. Please try again later.";
        }

        // Close statement
        mysqli_stmt_close($stmt);
    }
}

// Close connection
mysqli_close($link);

That's my register.php what I only changed.

if(empty($username_err) && empty($password_err) && empty($confirm_password_err)){
    
    // Prepare an insert statement
    $sql = "INSERT INTO users (username, password) VALUES (?, ?)";
     
    if($stmt = mysqli_prepare($link, $sql)){
        // Bind variables to the prepared statement as parameters
        mysqli_stmt_bind_param($stmt, "ss", $param_username, $param_password);
        
        // Set parameters
        $param_username = $username;
        $param_password = hash("sha256" , $_POST['password']); // Creates a password hash //<------------------THAT IS CHANGED
        
        // Attempt to execute the prepared statement
        if(mysqli_stmt_execute($stmt)){
            // Redirect to login page
            header("location: login.php");
        } else{
            echo "Oops! Something went wrong. Please try again later.";
        }

        // Close statement
        mysqli_stmt_close($stmt);
    }
}

// Close connection
mysqli_close($link);
}

`password_verify` is not for `hash("sha256"`, use [password_hash](https://www.php.net/manual/en/function.password-hash.php) instead — Lawrence Cherone, Oct 28 '21 at 22:00
no, but you shouldn't really be storing passwords in that format (especially without salting). Use [hash_equals](https://www.php.net/manual/en/function.hash-equals.php) to compare hashes — Lawrence Cherone, Oct 28 '21 at 22:05

score 0 · Accepted Answer · answered Oct 28 '21 at 22:19

That´s because your plain password will never match a SHA256 encrypted text You may try to convert your plain password again to sha256 and compare it, but it´s a bad practice and like Lawrence said, you shouldn't really be storing passwords in that format

password_verify works with password_hash where you provide your plain password and the hash algo see documentation here

Login Problems with PHP

1 Answers1