Digest::MultiHash(3pm)					User Contributed Perl Documentation				    Digest::MultiHash(3pm)

NAME

       Digest::MultiHash - XOR based, variable width multiplexing of hashes (a generalized Digest::SV1).

SYNOPSIS

	       use Digest::MultiHash;

	       my $d = Digest::Multihash->new(
		       width => 16, # bytes
		       hashs => ["SHA-512", "Whirlpool"], # see below for arbitrary arguments
	       );

	       $d->add($data);

	       print $d->hexdigest;

DESCRIPTION

       This class inherits from Digest::base, and provides generalized digest multiplexing.

       It will multiplex all calls to "add" to all of it's sub digest objects.	Likewise, when the final digest is extracted the digests will be
       extracted and then XOR'd over eachother according to "width".

       "width" will default to the width of the first hash if unspecified.

       "hashes" defaults to "SHA-1" for compatibility reasons.

       This module is useful for generating keys from passphrases, by supplying the desired width and simply making sure there is enough data from
       the combined hashes.

METHODS

       See Digest for the complete API. This module inherits from Digest::base.

       new This methods accepts a hash reference or an even sized list of parameters named according to the methods.

       add
       digest
	   Compute the hash by calling "digest" on all of the subhashes, splitting the result up into "width" sized chunk, and then XORing these
	   together.

	   If the result is not aligned on "width" the result will not be truncated. The shorter string will still be XOR'd with the hash, even if
	   this only affects part of the result.

	   If there are not at least "width" bytes of data in the output of the combined hashes an error is thrown.

       clone
	   Clones the hash.

       hashes
	   Get the array of hashes to use. Array values in this will be dereferenced before the call to "new" in Digest to allow passing of
	   arbitrary arguments.  Blessed objects (of any class) will be used verbatim.

	   The list of hashes cannot be changed after construction.

       width
	   Get/set the byte-width to use.

SEE ALSO

       Digest, Digest::SV1, Digest::SHA1

perl v5.14.2							    2009-10-19						    Digest::MultiHash(3pm)