Rhash(3pm)						User Contributed Perl Documentation						Rhash(3pm)

NAME

       Rhash - Perl extension for LibRHash Hash library

SYNOPSIS

	 use Rhash;

	 my $msg = "a message text";
	 print "MD5 = " . Rhash->new(Rhash::MD5)->update($msg)->hash() . "
";

	 # more complex example - calculate two hash functions simultaniously
	 my $r = Rhash->new(Rhash::MD5 | Rhash::SHA1);
	 $r->update("a message text")->update(" another message");
	 print	"MD5  = ". $r->hash(Rhash::MD5) . "
";
	 print	"SHA1 = ". $r->hash(Rhash::SHA1) . "
";

DESCRIPTION

       Rhash module is an object-oriented interface to the LibRHash library, which allows one to simultaniously calculate several hash functions
       for a file or a text message.

SUPPORTED ALGORITHMS

       The module supports the following hashing algorithms: CRC32,  MD4, MD5,	SHA1, SHA256, SHA512, AICH, ED2K, Tiger,  DC++ TTH,  BitTorrent
       BTIH, GOST R 34.11-94, RIPEMD-160, HAS-160, EDON-R 256/512, Whirlpool and Snefru-128/256.

CONSTRUCTOR

       Creates and returns new Rhash object.

	 my $r = Rhash->new($hash_id);
	 my $p = new Rhash($hash_id); # alternative way to call the constructor

       The $hash_id parameter can be union (via bitwise OR) of any of the following bit-flags:

	 Rhash::CRC32,
	 Rhash::MD4,
	 Rhash::MD5,
	 Rhash::SHA1,
	 Rhash::TIGER,
	 Rhash::TTH,
	 Rhash::BTIH,
	 Rhash::ED2K,
	 Rhash::AICH,
	 Rhash::WHIRLPOOL,
	 Rhash::RIPEMD160,
	 Rhash::GOST,
	 Rhash::GOST_CRYPTOPRO,
	 Rhash::HAS160,
	 Rhash::SNEFRU128,
	 Rhash::SNEFRU256,
	 Rhash::SHA224,
	 Rhash::SHA256,
	 Rhash::SHA384,
	 Rhash::SHA512,
	 Rhash::EDONR256,
	 Rhash::EDONR512

       Also the Rhash::ALL bit mask is the union of all listed bit-flags.  So the object created via Rhash->new(Rhash::ALL) calculates all
       supported hash functions for the same data.

COMPUTING HASHES

       $rhash->update( $msg )
	   Calculates hashes of the $msg string.  The method can be called repeatedly with chunks of the message to be hashed.	It returns the
	   $rhash object itself allowing the following construct:

	     $rhash = Rhash->new(Rhash::MD5)->update( $chunk1 )->update( $chunk2 );

       $rhash->update_file( $file_path, $start, $size )
       $rhash->update_fd( $fd, $start, $size )
	   Calculate a hash of the file (or its part) specified by $file_path or a file descriptor $fd.  The update_fd method doesn't close the
	   $fd, leaving the file position after the hashed block.  The optional $start and $size specify the block of the file to hash.  No error
	   is reported if the $size is grater than the number of the unread bytes left in the file.

	   Returns the number of characters actually read, 0 at end of file, or undef if there was an error (in the latter case $! is also set).

	     use Rhash;
	     my $r = new Rhash(Rhash::SHA1);
	     open(my $fd, "<", "input.txt") or die "cannot open < input.txt: $!";
	     while ((my $n = $r->update_fd($fd, undef, 1024) != 0) {
		 print "$n bytes hashed. The SHA1 hash is " . $r->final()->hash() . "
";
		 $r->reset();
	     }
	     defined($n) or die "read error for input.txt: $!";
	     close($fd);

       $rhash->final()
	   Finishes calculation for all data buffered by updating methods and stops hash calculation. The function is called automatically by any
	   of the $rhash->hash*() methods if the final() call was skipped.

       $rhash->reset()
	   Resets the $rhash object to the initial state.

       $rhash->hashed_length()
	   Returns the total length of the hashed message.

       $rhash->hash_id()
	   Returns the hash mask, the $rhash object was constructed with.

FORMATING HASH VALUE

       Computed hash can be formated as a hexadecimal string (in the forward or reverse byte order), a base32/base64-encoded string or as raw
       binary data.

       $rhash->hash( $hash_id )
	   Returns the hash string in the default format, which can be hexadecimal or base32. Actually the method is equvalent of

	     (Rhash::is_base32($hash_id) ? $rhash->hash_base32($hash_id) :
	       $rhash->hash_hex($hash_id))

	   If the optional $hash_id parameter is omited or zero, then the method returns the hash for the algorithm contained in $rhash with the
	   lowest identifier.

       $rhash->hash_hex( $hash_id )
	   Returns a specified hash in the hexadecimal format.

       $rhash->hash_rhex( $hash_id )
	   Returns a hexadecimal string of the hash in reversed bytes order.  Some programs prefer to output GOST hash in this format.

       $rhash->hash_base32( $hash_id )
	   Returns a specified hash in the base32 format.

       $rhash->hash_base64( $hash_id )
	   Returns a specified hash in the base64 format.

       $rhash->magnet_link( $filename, $hash_mask )
	   Returns the magnet link containing the computed hashes, filesize, and, optionaly, $filename. The $filename (if specified) is URL-
	   encoded, by converting special characters into the %<hexadecimal-code> form.  The optional parameter $hash_mask can limit which hash
	   values to put into the link.

STATIC INFORMATION METHODS

       Rhash::count()
	   Returns the number of supported hash algorithms

       Rhash::is_base32($hash_id)
	   Returns nonzero if default output format is Base32 for the hash function specified by $hash_id.  Retruns zero if default format is
	   hexadecimal.

       Rhash::get_digest_size($hash_id)
	   Returns the size in bytes of raw binary hash of the specified hash algorithm.

       Rhash::get_hash_length($hash_id)
	   Returns the length of a hash string in default output format for the specified hash algorithm.

       Rhash::get_name($hash_id)
	   Returns the name of the specified hash algorithm.

ALTERNATIVE WAY TO COMPUTE HASH

       Rhash::msg($hash_id, $message)
	   Computes and returns a single hash (in its default format) of the $message by the selected hash algorithm.

	     use Rhash;
	     print "SHA1( 'abc' ) = " . Rhash::msg(Rhash::SHA1, "abc");

LICENSE

	Permission is hereby granted, free of charge,  to any person obtaining a copy
	of this software and associated documentation files (the "Software"), to deal
	in the Software without restriction,  including without limitation the rights
	to  use,  copy,  modify,  merge, publish, distribute, sublicense, and/or sell
	copies	of  the Software,  and	to permit  persons  to whom  the Software  is
	furnished to do so.

	The Software  is distributed in the hope that it will be useful,  but WITHOUT
	ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
	FOR A PARTICULAR PURPOSE.  Use	this  program  at  your  own  risk!

perl v5.14.2							    2012-01-09								Rhash(3pm)