Im trying to make a SSO validation on thinktecture OpenId connect in PHP
I have written a client and get an access token. BUT i cannot find out how to validate it.
The documentation says:
3.2.2.9. Access Token Validation
To validate an Access Token issued from the Authorization Endpoint with an ID Token, the Client SHOULD do the following:
Hash the octets of the ASCII representation of the access_token with
the hash algorithm specified in JWA [JWA] for the alg Header
Parameter of the ID Token's JOSE Header. For instance, if the alg is
RS256, the hash algorithm used is SHA-256.
Take the left-most half of the hash and base64url encode it.
The value of at_hash in the ID Token MUST match the value produced
in the previous step.
I have no idea how to make step 1.
I got the ALg as RS256 and i have the at_hash from the Id token, i just cant find an exampel in PHP on how to do the validation.
Here is an example in PHP to calculate the at_hash value that should be easy to adapt to your environment:
public function setAccessTokenHash($accessTokenString)
{
// bit : 256/384/512
if(isset($this->_header['alg']) && $this->_header['alg'] != 'none'){
$bit = substr($this->_header['alg'], 2, 3);
}else{
// TODO: Error case. throw exception???
$bit = '256';
}
$len = ((int)$bit)/16;
$this->_payload['at_hash'] = Akita_OpenIDConnect_Util_Base64::urlEncode(substr(hash('sha'.$bit, $accessTokenString, true), 0, $len));
}
Related
The idea is to encrypt a string containing session data (username and token expiry) and store it in a cookie. Whenever an HTTP request comes from the client, the backend checks if it can decrypt the token in the cookie and then queries the DB to check if the username exists and is allowed to access the target resource:
// create token
$token = openssl_encrypt($username . "::" . $expiry, "rc2-40-cbc", $key, 0, "00000000");
// then store in cookie
'::' is just a delimiter.
// on http request, verify token
$decryptedToken = openssl_decrypt($token, "rc2-40-cbc", $key, 0, "00000000");
if($decryptedToken != false) // token is valid
// extract data
$tokenValues = explode("::", $token);
$username = $tokenValues[0];
$tokenExpiry = $tokenValues[1];
// then validate username and expiry
Is this safe?
Your code is absolutely insecure for multiple reasons. Please do not implement crypto without a basic understanding of what you are doing.
Using your method, the session data in the db would be cracked in less than a day with hardware that you have at home.
A few problems:
rc2-40-cbc is very, very weak
it is not an authenticated encryption
the IV is not for fun, you can't just put in zeroes because that worked
the result will not fit in a cookie if there is enough session data
the same session data would be encrypted to the same ciphertext
...
Please note that the solution is not changing the cipher and adding an IV. The solution is to use a well-known and tested library that does this for you.
The concept btw could work, but it has to be correctly implemented.
I want to use authentication token, after various searches I found JWT token and another token generation method with md5.
Off for various reasons I do not want to use the token JWT and md5 seems to me to have a bad reputation.
So I found a method but I would like your opinion:
Generating a Byte String: https://www.php.net/manual/en/function.random-bytes.php
Then I convert that into Hexadecimal.
Finally, I concatenate that with the id of my user and salting.
I send this to my application (Android or web) than during a request to my service I decode the received token, and I will see the token contained in the id hidden in the token.
So it is harder to find the token by brute force?
Note 1: that I would like to refresh the token by the future but for the moment it should be issued for an indefinite period.
Note 2: I do not want to use a library or framework just in php.
Code :
$bytes = random_bytes(32);
$part=bin2hex($bytes));
$shortpart=substr($part,0,17);
$id = #userid
$salt=#customsalt
$token=shortpart.$id.$salt;
Example :
$shortpart =f2e4d1f2a2dfedcf5
$id=1
$salt=4d2ze121
$token=f2e4d1f2a2dfedcf514d2ze121
The user or hacker doesn't know is id is hidden in the token.
After some research I think the better method is:
$token = bin2hex(openssl_random_pseudo_bytes(32));
And custom this string.
Add one column in database table for time and calculate authtoken as:
$time = time();
and store this to database.
Encryption:
$encrypt = base64_encode($time.userid);
Decryption:
Get the time from table:
$decrypt = base64_decode($encrypt);
Check this link.
I am developing an API using PHP and got the authentication part, I'm using token authentication.
This is the logical sequence I want to implement.
User Requests Access with Username / Password
Application validates credentials
Application provides a signed token to the client
Client stores that token and sends it along with every request
Server verifies token and responds with data
Example of use
user informs email and password, {"email":"emiry#hotmail.com", "senha":"123"}
I then send a token eiy#omlo3
whenever it accesses the API then it passes me that token
how will I know if this token is valid or not? will I have a function to validate the valid token? What is the logic to do this? to know if the token is valid
You could use the JWT (JSON Web Token) standard to learn more about this process. JSON web tokens are broken up into three parts all separated by a period:
header.payload.signature
The header is created by making claims about the token, for example its type and algorithm used:
$header = json_encode(['type' => 'JWT', 'algorithm' => 'HS256']);
More information on the difference between the signing algorithms
The payload contains important information that is used by the application, for example an identifier for a user. It can also contain other information like the expiration, issuer, etc:
$payload = json_encode([
'user_id' => 56,
// set expiration to 2 hours from now etc
]);
These can then by encoded with the base64_encode() and hash_hmac() functions.
The signature is a special part. It is a concatenation of the header and payload, with an appended "secret". The secret is a string that is only known by you and your application. Adding this to your token "signs" it, and makes it so that you're the only one that can properly validate it. This might be a good site to generate a "secret".
You would store the secret in a secure place outside of your publicly accessible folder, and retrieve it when needed (dotenv libraries are great for this). Those are all appended together and encoded to create your token and give to the client.
When you receive the token to validate, you can explode it into three parts since each is separated by a period, and then validate each piece to your liking. For example if you received a token you could do the following:
// validate token in header.payload.signature format
$token = explode('.', $token);
$header = $token[0]; // header should be first
$payload = $token[1]; // payload should be second
$signature = $token[2]; // signature should be third
Remember the signature is a hash of the header, payload, and secret. So you could decode this, and compare it to $token[0] and $token[1] to ensure that the token was not tampered with, and finally make sure that the secret matches as well.
Reference: How to Create a JSON Web Token Using PHP
I'm creating a sort of 'social network'. Now I'm creating the authentication part. Today I learned about JSON Web Tokens.
1) I read that JWT's are safe to use, because the are signed with a secret key. But then I found some tools online like https://jwt.io. I tried to build some JWT tokens with PHP using firebase/php-jwt. The tools like jwt.io can extract the data I put in the JWT (like user ID). How can this be safe? Can't someone just create a new JWT using the old one but with a different user ID?
An example: I created the following token:
eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJpc3MiOiJNeUFQIiwiaWF0IjoxNTE2NTYzMTM0LCJleHAiOjE1MTY1NjQzNDAsImF1ZCI6Ind3dy5leGFtcGxlLmNvbSIsInN1YiI6ImFkbWluQGV4YW1wbGUuY29tIiwibmFtZSI6IkpvaG4gRG9lIiwiYWRtaW4iOiJmYWxzZSJ9.dCtYVpFXhoQmzOdX_dW1yFHEcZ9aZ1I9MC33lJGapvY
If you paste this token in jwt.io, you'll see the payload is "name: John Doe" and "admin: false". Isn't this unsafe? Or is it safe because you NEED the secret key to recreate a JWT.
Off the record: You cannot store senstive information in a JWT I guess...
2) How to "login" a user using PHP and JWT's? I created a quick demo, I'm not sure the code "works" but I guess you'll see what I mean.
if (isset($_POST['submit'])) {
$user = $_POST['user'];
$pass = $_POST['pass'];
if($user = 'my_username' && $password == 'my_password') {
// user is logged in
// create a JWT here
} else {
// wrong credentials!
}
}
Now, the question/problem is: how to store this token? In a cookie? In a session? Using HTML5's localStorage? What is the safest way to do this?
And secondly: how to authenticate the user? I would do it like this:
// my secret key
$secret = 'MY_SECRET_KEY';
// decode the token
$token = JWT::decode($token, $secret, array('HS256'));
// what to do here?
Can you match this token with some data in a database or something?
1) The JWT token is not encrypted, so the data inside it can be easily read. However, it contains a signature that can be validated only with the secret key you have set when creating the token. You can check the signature to see that the token has not been tampered with.
2) The token can be stored anywhere, since it's so small. Just remember that the token can be easily read, but not altered. Don't store any sensitive data in the tokens.
When checking the token, the important things to check are the signature and the exp time to see that the token is still valid. A well-constructed token doesn't need full database validation, but rather just check that the user's privileges haven't been changed since issuing the token, and if they have, recreate the token with the updated data or force the user to log in again.
I want to use methods and resources from the code of a website which is developed in PHPFox.
Basically, I'll receive request from iPhone/Android, I'll get the request and pass to the respective function from the PHPFox code, take the response from that function and return it back to the device.
For this purpose I've developed REST APIs using Slim framework.
But the major blocker I'm facing currently is in accessing the resources(i.e. functions and data) of PHPFox website.
I'm not understanding how should I authenticate the user using 'Token Based Authentication' in order to access the website's resources.
If someone could guide me in proper direction with some useful working example it would be really helpful for me.
N.B. : The proposed implementation of 'Token Based Authentication' should be very secure and fast in speed. The security should not be compromised in any way.
Following is the code I tried on my own but I don't know whether it's right or wrong. Is my approach correct or wrong. Please someone analyse it and let me know your feedback on it.
To create a token i use this function which takes as parameters, the user's data
define('SECRET_KEY', "fakesecretkey");
function createToken($data)
{
/* Create a part of token using secretKey and other stuff */
$tokenGeneric = SECRET_KEY.$_SERVER["SERVER_NAME"]; // It can be 'stronger' of course
/* Encoding token */
$token = hash('sha256', $tokenGeneric.$data);
return array('token' => $token, 'userData' => $data);
}
So a user can authentified himself and receive an array which contains a token (genericPart + his data, encoded), and hisData not encoded :
function auth($login, $password)
{
// we check user. For instance, it's ok, and we get his ID and his role.
$userID = 1;
$userRole = "admin";
// Concatenating data with TIME
$data = time()."_".$userID."-".$userRole;
$token = createToken($data);
echo json_encode($token);
}
Then the user can send me his token + his un-encoded data in order to check :
define('VALIDITY_TIME', 3600);
function checkToken($receivedToken, $receivedData)
{
/* Recreate the generic part of token using secretKey and other stuff */
$tokenGeneric = SECRET_KEY.$_SERVER["SERVER_NAME"];
// We create a token which should match
$token = hash('sha256', $tokenGeneric.$receivedData);
// We check if token is ok !
if ($receivedToken != $token)
{
echo 'wrong Token !';
return false;
}
list($tokenDate, $userData) = explode("_", $receivedData);
// here we compare tokenDate with current time using VALIDITY_TIME to check if the token is expired
// if token expired we return false
// otherwise it's ok and we return a new token
return createToken(time()."#".$userData);
}
$check = checkToken($_GET['token'], $_GET['data']);
if ($check !== false)
echo json_encode(array("secureData" => "Oo")); // And we add the new token for the next request
Am I right?
Thanks.
1st you should understand what's token based authentication. It could be explained as below.
The general concept behind a token-based authentication system is
simple. Allow users to enter their username and password in order to
obtain a token which allows them to fetch a specific resource -
without using their username and password. Once their token has been
obtained, the user can offer the token - which offers access to a
specific resource for a time period - to the remote site.
Read more
Now let's see what are the steps of implementing it in your REST web service.
It will use the following flow of control:
The user provides a username and password in the login form and clicks Log In.
After a request is made, validate the user on the backend by querying in the database. If the request is valid, create a token by
using the user information fetched from the database, and then return
that information in the response header so that we can store the token
browser in local storage.
Provide token information in every request header for accessing restricted endpoints in the application.
If the token fetched from the request header information is valid, let the user access the specified end point, and respond with JSON or
XML.
See the image below for the flow of control
You might be wondering what's a JWT
JWT stands for JSON Web Token and is a token format used in
authorization headers. This token helps you to design communication
between two systems in a secure way. Let's rephrase JWT as the "bearer
token" for the purposes of this tutorial. A bearer token consists of
three parts: header, payload, and signature.
The header is the part of the token that keeps the token type and encryption method, encoded in base64.
The payload includes the information. You can put any kind of data like user info, product info and so on, all of which is also stored in
base64 encoding.
The signature consists of combinations of the header, payload, and secret key. The secret key must be kept securely on the server-side.
You can see the JWT schema and an example token below;
You do not need to implement the bearer token generator as you can use php-jwt.
Hope the above explains your confusion. if you come across any issues implementing token based authentication let me know. I can help you.