digest::file(3pm) [suse man page]

Digest::file(3pm)					 Perl Programmers Reference Guide					 Digest::file(3pm)

NAME

       Digest::file - Calculate digests of files

SYNOPSIS

	 # Poor mans "md5sum" command
	 use Digest::file qw(digest_file_hex);
	 for (@ARGV) {
	     print digest_file_hex($_, "MD5"), "  $_
";
	 }

DESCRIPTION

       This module provide 3 convenience functions to calculate the digest of files.  The following functions are provided:

       digest_file( $file, $algorithm, [$arg,...] )
	   This function will calculate and return the binary digest of the bytes of the given file.  The function will croak if it fails to open
	   or read the file.

	   The $algorithm is a string like "MD2", "MD5", "SHA-1", "SHA-512".  Additional arguments are passed to the constructor for the
	   implementation of the given algorithm.

       digest_file_hex( $file, $algorithm, [$arg,...] )
	   Same as digest_file(), but return the digest in hex form.

       digest_file_base64( $file, $algorithm, [$arg,...] )
	   Same as digest_file(), but return the digest as a base64 encoded string.

SEE ALSO

       Digest

perl v5.12.1							    2010-04-26							 Digest::file(3pm)

Digest(3pm)						 Perl Programmers Reference Guide					       Digest(3pm)

NAME

       Digest:: - Modules that calculate message digests

SYNOPSIS

	 $md2 = Digest->MD2;
	 $md5 = Digest->MD5;

	 $sha1 = Digest->SHA1;
	 $sha1 = Digest->new("SHA-1");

	 $hmac = Digest->HMAC_MD5($key);

DESCRIPTION

       The "Digest::" modules calculate digests, also called "fingerprints" or "hashes", of some data, called a message.  The digest is (usually)
       some small/fixed size string.  The actual size of the digest depend of the algorithm used.  The message is simply a sequence of arbitrary
       bytes.

       An important property of the digest algorithms is that the digest is likely to change if the message change in some way.  Another property
       is that digest functions are one-way functions, i.e. it should be hard to find a message that correspond to some given digest.  Algorithms
       differ in how "likely" and how "hard", as well as how efficient they are to compute.

       All "Digest::" modules provide the same programming interface.  A functional interface for simple use, as well as an object oriented inter-
       face that can handle messages of arbitrary length and which can read files directly.

       The digest can be delivered in three formats:

       binary  This is the most compact form, but it is not well suited for printing or embedding in places that can't handle arbitrary data.

       hex     A twice as long string of (lowercase) hexadecimal digits.

       base64  A string of portable printable characters.  This is the base64 encoded representation of the digest with any trailing padding
	       removed.  The string will be about 30% longer than the binary version.  MIME::Base64 tells you more about this encoding.

       The functional interface is simply importable functions with the same name as the algorithm.  The functions take the message as argument
       and return the digest.  Example:

	 use Digest::MD5 qw(md5);
	 $digest = md5($message);

       There are also versions of the functions with "_hex" or "_base64" appended to the name, which returns the digest in the indicated form.

OO INTERFACE

       The following methods are available for all "Digest::" modules:

       $ctx = Digest->XXX($arg,...)
       $ctx = Digest->new(XXX => $arg,...)
       $ctx = Digest::XXX->new($arg,...)
	   The constructor returns some object that encapsulate the state of the message-digest algorithm.  You can add data to the object and
	   finally ask for the digest.	The "XXX" should of course be replaced by the proper name of the digest algorithm you want to use.

	   The two first forms are simply syntactic sugar which automatically load the right module on first use.  The second form allow you to
	   use algorithm names which contains letters which are not legal perl identifiers, e.g. "SHA-1".

	   If new() is called as an instance method (i.e. $ctx->new) it will just reset the state the object to the state of a newly created
	   object.  No new object is created in this case, and the return value is the reference to the object (i.e. $ctx).

       $ctx->reset
	   This is just an alias for $ctx->new.

       $ctx->add($data,...)
	   The $data provided as argument are appended to the message we calculate the digest for.  The return value is the $ctx object itself.

       $ctx->addfile($io_handle)
	   The $io_handle is read until EOF and the content is appended to the message we calculate the digest for.  The return value is the $ctx
	   object itself.

       $ctx->digest
	   Return the binary digest for the message.

	   Note that the "digest" operation is effectively a destructive, read-once operation. Once it has been performed, the $ctx object is
	   automatically "reset" and can be used to calculate another digest value.

       $ctx->hexdigest
	   Same as $ctx->digest, but will return the digest in hexadecimal form.

       $ctx->b64digest
	   Same as $ctx->digest, but will return the digest as a base64 encoded string.

SEE ALSO

       Digest::MD5, Digest::SHA1, Digest::HMAC, Digest::MD2

       MIME::Base64

AUTHOR

       Gisle Aas <gisle@aas.no>

       The "Digest::" interface is based on the interface originally developed by Neil Winton for his "MD5" module.

perl v5.8.0							    2002-06-01							       Digest(3pm)