[perl5.git] / lib / Digest.pm

package Digest;

use strict;
use vars qw($VERSION %MMAP $AUTOLOAD);

$VERSION = "1.10";

%MMAP = (
  "SHA-1"      => ["Digest::SHA1", ["Digest::SHA", 1], ["Digest::SHA2", 1]],
  "SHA-256"    => [["Digest::SHA", 256], ["Digest::SHA2", 256]],
  "SHA-384"    => [["Digest::SHA", 384], ["Digest::SHA2", 384]],
  "SHA-512"    => [["Digest::SHA", 512], ["Digest::SHA2", 512]],
  "HMAC-MD5"   => "Digest::HMAC_MD5",
  "HMAC-SHA-1" => "Digest::HMAC_SHA1",
  "CRC-16"     => [["Digest::CRC", type => "crc16"]],
  "CRC-32"     => [["Digest::CRC", type => "crc32"]],
  "CRC-CCITT"  => [["Digest::CRC", type => "crcccitt"]],
);

sub new
{
    shift;  # class ignored
    my $algorithm = shift;
    my $impl = $MMAP{$algorithm} || do {
	$algorithm =~ s/\W+//;
	"Digest::$algorithm";
    };
    $impl = [$impl] unless ref($impl);
    my $err;
    for  (@$impl) {
	my $class = $_;
	my @args;
	($class, @args) = @$class if ref($class);
	no strict 'refs';
	unless (exists ${"$class\::"}{"VERSION"}) {
	    eval "require $class";
	    if ($@) {
		$err ||= $@;
		next;
	    }
	}
	return $class->new(@args, @_);
    }
    die $err;
}

sub AUTOLOAD
{
    my $class = shift;
    my $algorithm = substr($AUTOLOAD, rindex($AUTOLOAD, '::')+2);
    $class->new($algorithm, @_);
}

1;

__END__

=head1 NAME

Digest - Modules that calculate message digests

=head1 SYNOPSIS

  $md5  = Digest->new("MD5");
  $sha1 = Digest->new("SHA-1");
  $sha256 = Digest->new("SHA-256");
  $sha384 = Digest->new("SHA-384");
  $sha512 = Digest->new("SHA-512");

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

=head1 DESCRIPTION

The C<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 or bits.

An important property of the digest algorithms is that the digest is
I<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 I<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 C<Digest::> modules provide the same programming interface.  A
functional interface for simple use, as well as an object oriented
interface that can handle messages of arbitrary length and which can
read files directly.

The digest can be delivered in three formats:

=over 8

=item I<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.

=item I<hex>

A twice as long string of lowercase hexadecimal digits.

=item I<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.
L<MIME::Base64> tells you more about this encoding.

=back


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.

=head1 OO INTERFACE

The following methods are available for all C<Digest::> modules:

=over 4

=item $ctx = Digest->XXX($arg,...)

=item $ctx = Digest->new(XXX => $arg,...)

=item $ctx = Digest::XXX->new($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 no implementation for the given algorithm
can be found, then an exception is raised.

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).

=item $other_ctx = $ctx->clone

The clone method creates a copy of the digest state object and returns
a reference to the copy.

=item $ctx->reset

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

=item $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.

=item $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.

=item $ctx->add_bits( $data, $nbits )

=item $ctx->add_bits( $bitstring )

The bits provided are appended to the message we calculate the digest
for.  The return value is the $ctx object itself.

The two argument form of add_bits() will add the first $nbits bits
from data.  For the last potentially partial byte only the high order
C<< $nbits % 8 >> bits are used.  If $nbits is greater than C<<
length($data) * 8 >>, then this method would do the same as C<<
$ctx->add($data) >>, i.e. $nbits is silently ignored.

The one argument form of add_bits() takes a $bitstring of "1" and "0"
chars as argument.  It's a shorthand for C<< $ctx->add_bits(pack("B*",
$bitstring), length($bitstring)) >>.

This example shows two calls that should have the same effect:

   $ctx->add_bits("111100001010");
   $ctx->add_bits("\xF0\xA0", 12);

Most digest algorithms are byte based.  For those it is not possible
to add bits that are not a multiple of 8, and the add_bits() method
will croak if you try.

=item $ctx->digest

Return the binary digest for the message.

Note that the C<digest> operation is effectively a destructive,
read-once operation. Once it has been performed, the $ctx object is
automatically C<reset> and can be used to calculate another digest
value.  Call $ctx->clone->digest if you want to calculate the digest
without reseting the digest state.

=item $ctx->hexdigest

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

=item $ctx->b64digest

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

=back

=head1 Digest speed

This table should give some indication on the relative speed of
different algorithms.  It is sorted by throughput based on a benchmark
done with of some implementations of this API:

 Algorithm      Size    Implementation                  MB/s

 MD4            128     Digest::MD4 v1.3               165.0
 MD5            128     Digest::MD5 v2.33               98.8
 SHA-256        256     Digest::SHA2 v1.1.0             66.7
 SHA-1          160     Digest::SHA v4.3.1              58.9
 SHA-1          160     Digest::SHA1 v2.10              48.8
 SHA-256        256     Digest::SHA v4.3.1              41.3
 Haval-256      256     Digest::Haval256 v1.0.4         39.8
 SHA-384        384     Digest::SHA2 v1.1.0             19.6
 SHA-512        512     Digest::SHA2 v1.1.0             19.3
 SHA-384        384     Digest::SHA v4.3.1              19.2
 SHA-512        512     Digest::SHA v4.3.1              19.2
 Whirlpool      512     Digest::Whirlpool v1.0.2        13.0
 MD2            128     Digest::MD2 v2.03                9.5

 Adler-32        32     Digest::Adler32 v0.03            1.3
 CRC-16          16     Digest::CRC v0.05                1.1
 CRC-32          32     Digest::CRC v0.05                1.1
 MD5            128     Digest::Perl::MD5 v1.5           1.0
 CRC-CCITT       16     Digest::CRC v0.05                0.8

These numbers was achieved Apr 2004 with ActivePerl-5.8.3 running
under Linux on a P4 2.8 GHz CPU.  The last 5 entries differ by being
pure perl implementations of the algorithms, which explains why they
are so slow.

=head1 SEE ALSO

L<Digest::Adler32>, L<Digest::CRC>, L<Digest::Haval256>,
L<Digest::HMAC>, L<Digest::MD2>, L<Digest::MD4>, L<Digest::MD5>,
L<Digest::SHA>, L<Digest::SHA1>, L<Digest::SHA2>, L<Digest::Whirlpool>

New digest implementations should consider subclassing from L<Digest::base>.

L<MIME::Base64>

=head1 AUTHOR

Gisle Aas <gisle@aas.no>

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

This library is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.

    Copyright 1998-2001,2003-2004 Gisle Aas.
    Copyright 1995-1996 Neil Winton.

=cut
Commit	Line	Data
3357b1b1 JH	1	package Digest;
	2
	3	use strict;
	4	use vars qw($VERSION %MMAP $AUTOLOAD);
	5
a9acc356	6	$VERSION = "1.10";
3357b1b1 JH	7
3357b1b1 JH	8	%MMAP = (
b12d758c NC	9	"SHA-1" => ["Digest::SHA1", ["Digest::SHA", 1], ["Digest::SHA2", 1]],
	10	"SHA-256" => [["Digest::SHA", 256], ["Digest::SHA2", 256]],
	11	"SHA-384" => [["Digest::SHA", 384], ["Digest::SHA2", 384]],
	12	"SHA-512" => [["Digest::SHA", 512], ["Digest::SHA2", 512]],
3357b1b1 JH	13	"HMAC-MD5" => "Digest::HMAC_MD5",
3357b1b1 JH	14	"HMAC-SHA-1" => "Digest::HMAC_SHA1",
371dcd31 RGS	15	"CRC-16" => [["Digest::CRC", type => "crc16"]],
	16	"CRC-32" => [["Digest::CRC", type => "crc32"]],
	17	"CRC-CCITT" => [["Digest::CRC", type => "crcccitt"]],
3357b1b1 JH	18	);
	19
	20	sub new
	21	{
	22	shift; # class ignored
	23	my $algorithm = shift;
b12d758c NC	24	my $impl = $MMAP{$algorithm} \|\| do {
	25	$algorithm =~ s/\W+//;
	26	"Digest::$algorithm";
	27	};
	28	$impl = [$impl] unless ref($impl);
	29	my $err;
	30	for (@$impl) {
	31	my $class = $_;
	32	my @args;
	33	($class, @args) = @$class if ref($class);
	34	no strict 'refs';
	35	unless (exists ${"$class\::"}{"VERSION"}) {
	36	eval "require $class";
	37	if ($@) {
	38	$err \|\|= $@;
	39	next;
	40	}
	41	}
	42	return $class->new(@args, @_);
3357b1b1	43	}
b12d758c	44	die $err;
3357b1b1 JH	45	}
	46
	47	sub AUTOLOAD
	48	{
	49	my $class = shift;
	50	my $algorithm = substr($AUTOLOAD, rindex($AUTOLOAD, '::')+2);
	51	$class->new($algorithm, @_);
	52	}
	53
	54	1;
	55
	56	__END__
	57
	58	=head1 NAME
	59
e19eb3c1	60	Digest - Modules that calculate message digests
3357b1b1 JH	61
	62	=head1 SYNOPSIS
	63
e19eb3c1	64	$md5 = Digest->new("MD5");
3357b1b1	65	$sha1 = Digest->new("SHA-1");
e19eb3c1 NC	66	$sha256 = Digest->new("SHA-256");
	67	$sha384 = Digest->new("SHA-384");
	68	$sha512 = Digest->new("SHA-512");
3357b1b1 JH	69
	70	$hmac = Digest->HMAC_MD5($key);
	71
	72	=head1 DESCRIPTION
	73
	74	The C<Digest::> modules calculate digests, also called "fingerprints"
	75	or "hashes", of some data, called a message. The digest is (usually)
	76	some small/fixed size string. The actual size of the digest depend of
	77	the algorithm used. The message is simply a sequence of arbitrary
b12d758c	78	bytes or bits.
3357b1b1 JH	79
	80	An important property of the digest algorithms is that the digest is
	81	I<likely> to change if the message change in some way. Another
	82	property is that digest functions are one-way functions, i.e. it
	83	should be I<hard> to find a message that correspond to some given
	84	digest. Algorithms differ in how "likely" and how "hard", as well as
	85	how efficient they are to compute.
	86
	87	All C<Digest::> modules provide the same programming interface. A
	88	functional interface for simple use, as well as an object oriented
	89	interface that can handle messages of arbitrary length and which can
	90	read files directly.
	91
	92	The digest can be delivered in three formats:
	93
	94	=over 8
	95
	96	=item I<binary>
	97
	98	This is the most compact form, but it is not well suited for printing
	99	or embedding in places that can't handle arbitrary data.
	100
	101	=item I<hex>
	102
e19eb3c1	103	A twice as long string of lowercase hexadecimal digits.
3357b1b1 JH	104
	105	=item I<base64>
	106
	107	A string of portable printable characters. This is the base64 encoded
	108	representation of the digest with any trailing padding removed. The
	109	string will be about 30% longer than the binary version.
	110	L<MIME::Base64> tells you more about this encoding.
	111
	112	=back
	113
	114
	115	The functional interface is simply importable functions with the same
	116	name as the algorithm. The functions take the message as argument and
	117	return the digest. Example:
	118
	119	use Digest::MD5 qw(md5);
	120	$digest = md5($message);
	121
	122	There are also versions of the functions with "_hex" or "_base64"
	123	appended to the name, which returns the digest in the indicated form.
	124
	125	=head1 OO INTERFACE
	126
	127	The following methods are available for all C<Digest::> modules:
	128
	129	=over 4
	130
	131	=item $ctx = Digest->XXX($arg,...)
	132
	133	=item $ctx = Digest->new(XXX => $arg,...)
	134
	135	=item $ctx = Digest::XXX->new($arg,...)
	136
	137	The constructor returns some object that encapsulate the state of the
	138	message-digest algorithm. You can add data to the object and finally
	139	ask for the digest. The "XXX" should of course be replaced by the proper
	140	name of the digest algorithm you want to use.
	141
	142	The two first forms are simply syntactic sugar which automatically
	143	load the right module on first use. The second form allow you to use
	144	algorithm names which contains letters which are not legal perl
897ff129 RGS	145	identifiers, e.g. "SHA-1". If no implementation for the given algorithm
897ff129 RGS	146	can be found, then an exception is raised.
3357b1b1	147
67859229	148	If new() is called as an instance method (i.e. $ctx->new) it will just
3357b1b1 JH	149	reset the state the object to the state of a newly created object. No
	150	new object is created in this case, and the return value is the
	151	reference to the object (i.e. $ctx).
	152
70ee4409 JH	153	=item $other_ctx = $ctx->clone
	154
	155	The clone method creates a copy of the digest state object and returns
	156	a reference to the copy.
	157
3357b1b1 JH	158	=item $ctx->reset
	159
	160	This is just an alias for $ctx->new.
	161
e19eb3c1	162	=item $ctx->add( $data, ... )
3357b1b1 JH	163
	164	The $data provided as argument are appended to the message we
	165	calculate the digest for. The return value is the $ctx object itself.
	166
e19eb3c1	167	=item $ctx->addfile( $io_handle )
3357b1b1 JH	168
	169	The $io_handle is read until EOF and the content is appended to the
	170	message we calculate the digest for. The return value is the $ctx
	171	object itself.
	172
e19eb3c1	173	=item $ctx->add_bits( $data, $nbits )
b12d758c	174
e19eb3c1	175	=item $ctx->add_bits( $bitstring )
b12d758c NC	176
	177	The bits provided are appended to the message we calculate the digest
	178	for. The return value is the $ctx object itself.
	179
	180	The two argument form of add_bits() will add the first $nbits bits
	181	from data. For the last potentially partial byte only the high order
	182	C<< $nbits % 8 >> bits are used. If $nbits is greater than C<<
	183	length($data) * 8 >>, then this method would do the same as C<<
	184	$ctx->add($data) >>, i.e. $nbits is silently ignored.
	185
	186	The one argument form of add_bits() takes a $bitstring of "1" and "0"
	187	chars as argument. It's a shorthand for C<< $ctx->add_bits(pack("B*",
	188	$bitstring), length($bitstring)) >>.
	189
	190	This example shows two calls that should have the same effect:
	191
	192	$ctx->add_bits("111100001010");
	193	$ctx->add_bits("\xF0\xA0", 12);
	194
	195	Most digest algorithms are byte based. For those it is not possible
	196	to add bits that are not a multiple of 8, and the add_bits() method
	197	will croak if you try.
	198
3357b1b1 JH	199	=item $ctx->digest
	200
	201	Return the binary digest for the message.
	202
	203	Note that the C<digest> operation is effectively a destructive,
	204	read-once operation. Once it has been performed, the $ctx object is
	205	automatically C<reset> and can be used to calculate another digest
70ee4409 JH	206	value. Call $ctx->clone->digest if you want to calculate the digest
70ee4409 JH	207	without reseting the digest state.
3357b1b1 JH	208
	209	=item $ctx->hexdigest
	210
	211	Same as $ctx->digest, but will return the digest in hexadecimal form.
	212
	213	=item $ctx->b64digest
	214
	215	Same as $ctx->digest, but will return the digest as a base64 encoded
	216	string.
	217
	218	=back
	219
e19eb3c1 NC	220	=head1 Digest speed
	221
	222	This table should give some indication on the relative speed of
	223	different algorithms. It is sorted by throughput based on a benchmark
	224	done with of some implementations of this API:
	225
371dcd31 RGS	226	Algorithm Size Implementation MB/s
	227
	228	MD4 128 Digest::MD4 v1.3 165.0
	229	MD5 128 Digest::MD5 v2.33 98.8
	230	SHA-256 256 Digest::SHA2 v1.1.0 66.7
	231	SHA-1 160 Digest::SHA v4.3.1 58.9
	232	SHA-1 160 Digest::SHA1 v2.10 48.8
	233	SHA-256 256 Digest::SHA v4.3.1 41.3
	234	Haval-256 256 Digest::Haval256 v1.0.4 39.8
	235	SHA-384 384 Digest::SHA2 v1.1.0 19.6
	236	SHA-512 512 Digest::SHA2 v1.1.0 19.3
	237	SHA-384 384 Digest::SHA v4.3.1 19.2
	238	SHA-512 512 Digest::SHA v4.3.1 19.2
	239	Whirlpool 512 Digest::Whirlpool v1.0.2 13.0
	240	MD2 128 Digest::MD2 v2.03 9.5
	241
	242	Adler-32 32 Digest::Adler32 v0.03 1.3
	243	CRC-16 16 Digest::CRC v0.05 1.1
	244	CRC-32 32 Digest::CRC v0.05 1.1
	245	MD5 128 Digest::Perl::MD5 v1.5 1.0
	246	CRC-CCITT 16 Digest::CRC v0.05 0.8
	247
	248	These numbers was achieved Apr 2004 with ActivePerl-5.8.3 running
	249	under Linux on a P4 2.8 GHz CPU. The last 5 entries differ by being
e19eb3c1 NC	250	pure perl implementations of the algorithms, which explains why they
	251	are so slow.
	252
3357b1b1 JH	253	=head1 SEE ALSO
3357b1b1 JH	254
371dcd31 RGS	255	L<Digest::Adler32>, L<Digest::CRC>, L<Digest::Haval256>,
	256	L<Digest::HMAC>, L<Digest::MD2>, L<Digest::MD4>, L<Digest::MD5>,
	257	L<Digest::SHA>, L<Digest::SHA1>, L<Digest::SHA2>, L<Digest::Whirlpool>
e19eb3c1 NC	258
e19eb3c1 NC	259	New digest implementations should consider subclassing from L<Digest::base>.
3357b1b1 JH	260
	261	L<MIME::Base64>
	262
	263	=head1 AUTHOR
	264
	265	Gisle Aas <gisle@aas.no>
	266
	267	The C<Digest::> interface is based on the interface originally
	268	developed by Neil Winton for his C<MD5> module.
	269
e19eb3c1 NC	270	This library is free software; you can redistribute it and/or
	271	modify it under the same terms as Perl itself.
	272
897ff129	273	Copyright 1998-2001,2003-2004 Gisle Aas.
e19eb3c1 NC	274	Copyright 1995-1996 Neil Winton.
e19eb3c1 NC	275
3357b1b1	276	=cut