This question already has answers here:
How do I convert password hashing from MD5 to SHA?
(7 answers)
Closed 11 days ago.
I would like if it's possible to change the hashing method for an already hashed password. For example:
$password_input = '123456789';
$hashed_password = md5($password_input);
// The output would be 25f9e794323b453885f5181f1b624d0b
The result was made with the following online tool:
https://helloacm.com/md5/
The next step would be insert the hashed password into the database. When I do this the given hashed password will be in the users table. If I select that password, can I change the md5 hash by a sha-256? For example:
$md5_password = '25f9e794323b453885f5181f1b624d0b';
$sha256_password = hash('sha256', $md5_password);
If this would be possible, would it break the login function? I mean if I use password_verify method, will it return true?
You will not get password back from md5, you can't unhash one way hash algorithms.
What we do - incorporate re-hashing in login flow.
User logins to your system with old hash password
You detect, that this user needs re-hash
While still having sent plain text password you hash it with new algorithm and save to database
Next time user logins with newly hashed password without problems
Related
This question already has answers here:
How does password salt help against a rainbow table attack?
(10 answers)
How can bcrypt have built-in salts?
(5 answers)
Password hashing, salt and storage of hashed values
(4 answers)
Closed 3 months ago.
I am wondering about how password_verify() verifies the hash, I have reviewed the documentation and many answers in StackOverflow, but I didn't get the idea
because, as I understood, this function will compare the hash with entered password after hashing it again, and use the same salt and cost and algorithm,
but the question here: if anyone can separate the salt from the hashed password, then anybody also can try to use rehash and try to match, and the salt will be useless here. Am I right, or what?
The salt have to be generated randomly each time the fonction is used (and it's what this function does, and not accept custom salt anymore).
For example:
<?php
$password = "nothing";
echo password_hash($password, PASSWORD_DEFAULT);
echo PHP_EOL;
echo password_hash($password, PASSWORD_DEFAULT);
Give the response :
$2y$10$mdJRjsoc1vR11SKa2JDyS.qSlxja/a0SUPuXC1NKsRLkzmayKwjku
$2y$10$H2th6dRY/i.xZzXSGxDZ1uaiwZx6s0.FM0NXcBcBQ0E2aNEHCJ57m
It's the same password with differents results.
The hashed password is stored in a database or a file. In this case, an admin system (or someone who's hacked the database) can't say if the same password is used by differents users. Another point, rainbow tables can't be used with hashed password with salt. Only brut force can be done.
Using the same salt for all is not more secure than using simple hash algorytm.
This question already has answers here:
How to use PHP's password_hash to hash and verify passwords
(5 answers)
Closed 2 years ago.
I hashed a password through
$hashedpassword = password_hash($Password, PASSWORD_DEFAULT);
This stores the password as a hashed value into a database.
But when I try to login in through
$Password=$_POST['Password'];
$hashedpassword = password_hash($Password, PASSWORD_DEFAULT);
if(password_verify($Password, $hashedpassword))
It will always tell me that the password is correct, regardless on whether it is or not.
Is there a way around this, so I can hash the password but login with the entered (non-hashed) password.
At some point in the past, when the account was created or when the password was last changed, you should have stored the hashed password.
You need to get the stored password hash from the database and use that with password_verify.
Currently, you are hashing the newly submitted password and verifying the submitted password against that, so of course, it always matches.
This question already has answers here:
Is it possible to decrypt MD5 hashes?
(24 answers)
Closed 8 years ago.
I want to get real password which is converted by wordpress into md5 format.
For example,
my md5 password is - 62cc2d8b4bf2d8728120d052163a77df
Real password - demo123.
I want to get real password from md5 version.
I tried this but didn't give me what I want -http://md5encryption.com/
You cannot unhash a password. That is the whole reason you hash a password in the first place.
It is possible to 'brute' force a password, or use a rainbow table to lookup the password - but that is why you (hopefully) used a salt on the password to ensure the hash is unique.
This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
what is best possible way of salting and storing salt?
Improve password hashing with a random salt
Assuming that using a correct algorithm for password hashing and generating different salts for each password...
Is it a security risk to store salts separately from password hashes? For ex. in a database table, storing password hashes in one column, and password salts in a separate column?
I saw strategies where the salt is embedded into the password hash itself, by using a specific algorithm. Later on the salt can be extracted from the password hash. Is this more secure?
From everything I have ever read and done, there is nothing wrong with storing the password hash and password salt in separate columns, and that is the most common way to do it.
The basic method for authentication should go something like this:
Retrieve user_id and password_salt using user supplied username or email
Concat user supplied password input with retrieved salt
Use hashing algorithm on combined string
Check created hash against the hash in the database
Please try to search StackOverflow before asking a question. Many questions are already answered. For example:
PHP & MySQL compare password
how do I create a mySQL user with hash(‘sha256’, $salt . $password)?
Secure hash and salt for PHP passwords
User Login with a single query and per-user password salt
Non-random salt for password hashes
Hi
I want that nobody can see my password even in database..
So i used hash function like this
$passowrd_hash=hash('shal',$_POST['password']);
Now easily I can store this password_hash value into database. It will be something like in encrypted form.
Now user know its original password he don't know this encrypted password.
Now if he try to login through this original password..He is not able to login.
So is there any method so that it can be decrypted and user can make log in. So he can achieve both security of password as well as login again.
How to do this?
you need to hash the user input password and compare hashes.
Before comparing the posted password by the user with the one in the database, encrypt the posted password the same way as the stored password.
All you need to do is encrypt the password you type in and compare the two; the hash in the database and the one you just encrypted. If they match then the password entered is the right one. I am assuming you are using an algorithm like SHA1.
As already answered, you need to hash the password every time they re-enter it and compare the hash to what is in your database.
You ALSO should look into using salt in your hashing algorithm. There is a good deal of discussion in this question:
Secure hash and salt for PHP passwords
You dont need to decrypt it. You cannot convert back a hash to a plain text, its a one way function. So, basically you hash the input password and compare the two hash:
E.g (pseudo code):-
if hash(password entered by user) == password stored in databse Then
//logged in successfully
else
//login failed
end if
I highly recommend using md5() http://php.net/manual/en/function.md5.php.
When the user signs up, you store:
$password = md5($_POST['password']);
And when the user logs in you check:
if($_POST['password_entered'] == $passwordFromDB) :
// Log user in
else :
// Show error to user
endif;