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