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