Space padded binary string in Python

I need to convert this PHP function into Python but I don't even know, what is space padded binary string.

pack('A*', $string);

Python has struct.pack what should be probably used but I end here. Can somebody help and explain me the behaviour?

Thanks!

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UPDATE:

This is the whole code I need to implement in Python. Until now I never heard about pack() so I am trying to understand what it exactly does so I can do it in Python:

function getSIGN($PID, $ID, $DESC, $PRICE, $URL, $EMAIL, $PWD) {
    $bHash = pack('A*', $PID . $I开发者_运维百科D . $DESC . $PRICE . $URL . $EMAIL);
    $bPWD = pack('A*', $PWD);
    $SIGN = strtoupper(hash_hmac('sha256', $bHash, $bPWD, false));
    return $SIGN;
}

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I think that is a noop.

$string = 'asdf';
print pack('A10', $string) . "|<-\n";

would give you

asdf      |<-

Since the * means "take as many as possible," there is never any reason to pad.

IMHO you can just throw away the whole line.

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Re. your Update:

The pack function still serves no purpose, except for maybe implicitely converting all non-string arguments to strings.

Here is how you would do it in Python. I took the liberty to change the order of the parameters, so I can use parameter packing (which is not at all like string packing ;).

import hmac, hashlib

def get_sign(key, *data):
     msg = ''.join(str(item) for item in data)
     h = hmac.new(key, msg, hashlib.sha256)
     return h.hexdigest().upper()

PHP:

$ print getSIGN(1234, 456, "foo", '123.45', 'http://example.com', 'foo@example.com', 'blah');  
7FA608240FA2DC04F15DB2CDB58C83F4ED6C28C5C5B4063C5A7605F9D69F170B

Python:

In [12]: get_sign('blah', 1234, 456, "foo", '123.45',
                  'http://example.com',  'foo@example.com')
Out[12]: '7FA608240FA2DC04F15DB2CDB58C83F4ED6C28C5C5B4063C5A7605F9D69F170B'