I'm using ActivePerl and pulled in Convert::Base32 using their PPM graphical tool. The entire issue derives from being able to decode/encode the URN:SHA1 strings used in Limewire.

Taking a SHA1 and encoding it to Base32 works just fine. However, I can't seem to take a Base32 encoding of a SHA1 and decode it. Any help would be greatly appreciated.

The encode part is based off of "Magnet URI Redirect Service" (1). Adding a comparable unpack to the decode function does not work either. Thanks again.

(1) http://magnet.pixelcort.com/ 
#!/usr/bin/env perl

use strict;
use warnings;
use Switch;
use Convert::Base32;

# Prompt user on which action they wish to take
print "[D]ecode or [E]ncode URN (default = D): ";
chomp (my $urn_format = <>);

# Execute appropriate function
switch (uc($urn_format)) {
    case "" { &urnDecode }
    case "D" { &urnDecode }
    case "E" { &urnEncode }
    else {print "Invalid option. Enter \"D\" to decode or \"E\" to enc
+ode."}
}

# Convert URN:SHA1 (base32) values to standard SHA1 (base16)
sub urnDecode {
    print "\nEnter URN to decode: ";
    chomp (my $urn_decode = <>);
    
    print "SHA1: " . decode_base32($urn_decode) . "\n";
}

# Convert SHA1 (base16) values to URN:SHA1 (base32)
sub urnEncode {
    print "\nEnter SHA1 to encode: ";
    chomp (my $urn_encode = <>);
    
    print "urn:sha1:" . uc(encode_base32(pack('H40', $urn_encode))) . 
+"\n";
}

exit 0;

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In reply to Decoding Base32 by Cynric

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