help tranlating perl expressions

I am trying to translate some perl code to python and I need some advice on
making fixed sized strings. The perl code creates a sha1 signatured using a
key and a 'pad'. It creates fixed sized strings as follows:

my $klen = length($key);
my $blen = 64;
my $ipad = chr(0x36)x$blen;
my $opad = chr(0x5c)x$blen;

I don't know if I ever seen any way in python of created a fixed size
string. Can anyone show me how to implement the same statements in python?

Next, it zero-fills a string to a certain size.

if($klen <= $blen) {
$key .= "\0"x($blen-length($key)); #zero-fill to blocksize
} else {
$key = sha1($key); #if longer, pre-hash key
}

Finally it concatenates and xors these strings together like this:

return sha1($key^$opad . sha1($key^$ipad . $data));

I when python XOR's strings, is it the same as when perl xor's them?

--
David Bear
-- let me buy your intellectual property, I want to own your thoughts --
.

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