How to get System.Text of C# in PHP?

Question

Below is the code of both C# and PHP, I need some help regarding it. I am trying to generate the authenticationKey which is in C# but want the convert in PHP. All is done but I don't know how to implement [System.Text] in PHP as there is hash_hmac() in PHP but what might be the $string in the same function.

C# Version

var hmac = new System.Security.Cryptography.HMACSHA256();
var buffer = userName + accessKey + timeStamp + originUrl;
var hash = hmac.ComputeHash(System.Text.Encoding.UTF8.GetBytes(buffer));
var authenticationKey = Convert.ToBase64String(hash);

PHP version

$hmac = hash_hmac('sha256', $string, $buffer);
$encoded = base64_encode($hmac);

Can anyone help me with that. It will be very helpful. Thanks.

Does this answer your question? [PHP and C# HMAC SHA256](https://stackoverflow.com/questions/33419006/php-and-c-sharp-hmac-sha256) — smolchanovsky, Feb 01 '20 at 07:37

Pruthvi Gandhi · Accepted Answer · 2020-03-02T05:12:38.573

I was also searching for this and atlast it was just a mistake of 1 small varibale, in the hash_hmac function pass the last value as true, this is will return raw output and when you convert it to base64 it will give the same output as the c# code.

$buffer = $userName.$accessKey.$timeStamp.$originUrl;
$hmac = hash_hmac('sha256', $buffer, $tokenSecret, true);
$authenticationKey = base64_encode($hmac);

Just in your c# function use the key, as shown in the code below

var hmac = new System.Security.Cryptography.HMACSHA256();
hmac.Key = System.Text.Encoding.UTF8.GetBytes(tokenSecret);

In my code I have tokenSecret variable in bas64 form.

score 0 · Answer 2 · answered Feb 01 '20 at 07:35

0

You may get the hex value, using unpack method:

$value = unpack('H*', buffer);
echo $value[1];

answered Feb 01 '20 at 07:35

Foued MOUSSI

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score 0 · Answer 3 · answered Feb 01 '20 at 07:43

In your c# code, you used a randomly generated key. Check the documentation: https://learn.microsoft.com/en-us/dotnet/api/system.security.cryptography.hmacsha256?view=netframework-4.8#constructors

HMACSHA256()

Initializes a new instance of the HMACSHA256 class with a randomly generated key.

HMACSHA256(Byte[])

Initializes a new instance of the HMACSHA256 class with the specified key data

Now the php documentation in comparison: https://www.php.net/manual/en/function.hash-hmac.php

hash_hmac ( string $algo , string $data , string $key [, bool $raw_output = FALSE ] ) : string

You see, what you call buffer in php, is actually the key and what you call buffer in c# is the data you hash.

So the$string should contain the data to be hashed.

As per the conversion, you don't need to get bytes in php: What is the PHP equivalent of this C# encoding code?

If you are saying $string should contain data to be hashed then what will come in $buffer. Actually I am integrating Payliance Payment Integration in my PHP Project and the above code is part of it. Any help regarding this documentation would also help. — Full Stop, Feb 03 '20 at 05:14
buffer = key Shared secret key used for generating the HMAC variant of the message digest. — Athanasios Kataras, Feb 03 '20 at 06:42

How to get System.Text of C# in PHP?

3 Answers3