SHA256 Hash in a connection

[kushakhan]

I need to connect to a REST API that uses SHA256 in its authentication. The pattern is this:

• generate a hash

• import secret key

• generate a SHA256 hash of the secter key and the salt

• Base-64 encode the hash

• url-encode the Base-64 encoded hash

• transmit the result in a header

I know how to do some of this. I can do it all in PHP, but that's not super useful right now. What i want ot know is:

1. How can I generate a SHA256 hash?

   1. in php, it would be: $salted_hash = hash_hmac('sha256', $salt, $secretKey, true);

2. How do I urlencode a string?

   1. in php it's simply $string = urlencode('string');

If it helps (or it there is an extension or shortcut to use) this is to connect to a Kayako Classic REST API.