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package Javascript::SHA1;

# Name:
#	Javascript::SHA1.
#
# Documentation:
#	POD-style documentation is at the end. Extract it with pod2html.*.
#
# Reference:
#	Object Oriented Perl
#	Damian Conway
#	Manning
#	1-884777-79-1
#	P 114
#
# Note:
#	o Tab = 4 spaces || die.
#
# Author:
#	Ron Savage <ron@savage.net.au>
#	Home page: http://savage.net.au/index.html
#
# Licence:
#	Australian copyright (c) 2004 Ron Savage.
#
#	All Programs of mine are 'OSI Certified Open Source Software';
#	you can redistribute them and/or modify them under the terms of
#	The Artistic License, a copy of which is available at:
#	http://www.opensource.org/licenses/index.html

use strict;
use warnings;
no warnings 'redefine';

require 5.005_62;

require Exporter;

our @ISA = qw(Exporter);

# Items to export into callers namespace by default. Note: do not export
# names by default without a very good reason. Use EXPORT_OK instead.
# Do not simply export all your public functions/methods/constants.

# This allows declaration	use Javascript::SHA1 ':all';
# If you do not need this, moving things directly into @EXPORT or @EXPORT_OK
# will save memory.
our %EXPORT_TAGS = ( 'all' => [ qw(

) ] );

our @EXPORT_OK = ( @{ $EXPORT_TAGS{'all'} } );

our @EXPORT = qw(

);
our $VERSION = '1.07';

# -----------------------------------------------

# Preloaded methods go here.

# -----------------------------------------------

# Encapsulated class data.

{
	my(%_attr_data) =
	(	# Alphabetical order.
	);

	sub _default_for
	{
		my($self, $attr_name) = @_;

		$_attr_data{$attr_name};
	}

	sub _standard_keys
	{
		keys %_attr_data;
	}

}	# End of encapsulated class data.

# -----------------------------------------------

sub javascript
{
	my($self, $field_name, $form_number) = @_;
	$field_name		||= 'password';
	$form_number	||= 0;

	return <<EOS;
/*
 * A JavaScript implementation of the Secure Hash Algorithm, SHA-1, as defined
 * in FIPS PUB 180-1
 * Version 2.1 Copyright Paul Johnston 2000 - 2002.
 * Other contributors: Greg Holt, Andrew Kepert, Ydnar, Lostinet
 * Distributed under the BSD License
 * See http://pajhome.org.uk/crypt/md5 for details.
 * Patch by Ron Savage 2004-04-27:
 * o Add the 3 functions str2hex_sha1, str2b64_sha1 and str2str_sha1().
 */

function str2hex_sha1()
{
	document.forms[$form_number].$field_name.value = hex_sha1(document.forms[$form_number].$field_name.value);
	return true;
}

function str2b64_sha1()
{
	document.forms[$form_number].$field_name.value = b64_sha1(document.forms[$form_number].$field_name.value);
	return true;
}

function str2str_sha1()
{
	document.forms[$form_number].$field_name.value = str_sha1(document.forms[$form_number].$field_name.value);
	return true;
}

/*
 * Configurable variables. You may need to tweak these to be compatible with
 * the server-side, but the defaults work in most cases.
 */
var hexcase = 0;  /* hex output format. 0 - lowercase; 1 - uppercase        */
var b64pad  = ""; /* base-64 pad character. "=" for strict RFC compliance   */
var chrsz   = 8;  /* bits per input character. 8 - ASCII; 16 - Unicode      */

/*
 * These are the functions you'll usually want to call.
 * They take string arguments and return either hex or base-64 encoded strings
 */
function hex_sha1(s){return binb2hex(core_sha1(str2binb(s),s.length * chrsz));}
function b64_sha1(s){return binb2b64(core_sha1(str2binb(s),s.length * chrsz));}
function str_sha1(s){return binb2str(core_sha1(str2binb(s),s.length * chrsz));}
function hex_hmac_sha1(key, data){ return binb2hex(core_hmac_sha1(key, data));}
function b64_hmac_sha1(key, data){ return binb2b64(core_hmac_sha1(key, data));}
function str_hmac_sha1(key, data){ return binb2str(core_hmac_sha1(key, data));}

/*
 * Perform a simple self-test to see if the VM is working
 */
function sha1_vm_test()
{
  return hex_sha1("abc") == "a9993e364706816aba3e25717850c26c9cd0d89d";
}

/*
 * Calculate the SHA-1 of an array of big-endian words, and a bit length
 */
function core_sha1(x, len)
{
  /* append padding */
  x[len >> 5] |= 0x80 << (24 - len % 32);
  x[((len + 64 >> 9) << 4) + 15] = len;

  var w = Array(80);
  var a =  1732584193;
  var b = -271733879;
  var c = -1732584194;
  var d =  271733878;
  var e = -1009589776;

  for(var i = 0; i < x.length; i += 16)
  {
    var olda = a;
    var oldb = b;
    var oldc = c;
    var oldd = d;
    var olde = e;

    for(var j = 0; j < 80; j++)
    {
      if(j < 16) w[j] = x[i + j];
      else w[j] = rol(w[j-3] ^ w[j-8] ^ w[j-14] ^ w[j-16], 1);
      var t = safe_add(safe_add(rol(a, 5), sha1_ft(j, b, c, d)),
                       safe_add(safe_add(e, w[j]), sha1_kt(j)));
      e = d;
      d = c;
      c = rol(b, 30);
      b = a;
      a = t;
    }

    a = safe_add(a, olda);
    b = safe_add(b, oldb);
    c = safe_add(c, oldc);
    d = safe_add(d, oldd);
    e = safe_add(e, olde);
  }
  return Array(a, b, c, d, e);

}

/*
 * Perform the appropriate triplet combination function for the current
 * iteration
 */
function sha1_ft(t, b, c, d)
{
  if(t < 20) return (b & c) | ((~b) & d);
  if(t < 40) return b ^ c ^ d;
  if(t < 60) return (b & c) | (b & d) | (c & d);
  return b ^ c ^ d;
}

/*
 * Determine the appropriate additive constant for the current iteration
 */
function sha1_kt(t)
{
  return (t < 20) ?  1518500249 : (t < 40) ?  1859775393 :
         (t < 60) ? -1894007588 : -899497514;
}

/*
 * Calculate the HMAC-SHA1 of a key and some data
 */
function core_hmac_sha1(key, data)
{
  var bkey = str2binb(key);
  if(bkey.length > 16) bkey = core_sha1(bkey, key.length * chrsz);

  var ipad = Array(16), opad = Array(16);
  for(var i = 0; i < 16; i++)
  {
    ipad[i] = bkey[i] ^ 0x36363636;
    opad[i] = bkey[i] ^ 0x5C5C5C5C;
  }

  var hash = core_sha1(ipad.concat(str2binb(data)), 512 + data.length * chrsz);
  return core_sha1(opad.concat(hash), 512 + 160);
}

/*
 * Add integers, wrapping at 2^32. This uses 16-bit operations internally
 * to work around bugs in some JS interpreters.
 */
function safe_add(x, y)
{
  var lsw = (x & 0xFFFF) + (y & 0xFFFF);
  var msw = (x >> 16) + (y >> 16) + (lsw >> 16);
  return (msw << 16) | (lsw & 0xFFFF);
}

/*
 * Bitwise rotate a 32-bit number to the left.
 */
function rol(num, cnt)
{
  return (num << cnt) | (num >>> (32 - cnt));
}

/*
 * Convert an 8-bit or 16-bit string to an array of big-endian words
 * In 8-bit function, characters >255 have their hi-byte silently ignored.
 */
function str2binb(str)
{
  var bin = Array();
  var mask = (1 << chrsz) - 1;
  for(var i = 0; i < str.length * chrsz; i += chrsz)
    bin[i>>5] |= (str.charCodeAt(i / chrsz) & mask) << (24 - i%32);
  return bin;
}

/*
 * Convert an array of big-endian words to a string
 */
function binb2str(bin)
{
  var str = "";
  var mask = (1 << chrsz) - 1;
  for(var i = 0; i < bin.length * 32; i += chrsz)
    str += String.fromCharCode((bin[i>>5] >>> (24 - i%32)) & mask);
  return str;
}

/*
 * Convert an array of big-endian words to a hex string.
 */
function binb2hex(binarray)
{
  var hex_tab = hexcase ? "0123456789ABCDEF" : "0123456789abcdef";
  var str = "";
  for(var i = 0; i < binarray.length * 4; i++)
  {
    str += hex_tab.charAt((binarray[i>>2] >> ((3 - i%4)*8+4)) & 0xF) +
           hex_tab.charAt((binarray[i>>2] >> ((3 - i%4)*8  )) & 0xF);
  }
  return str;
}

/*
 * Convert an array of big-endian words to a base-64 string
 */
function binb2b64(binarray)
{
  var tab = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  var str = "";
  for(var i = 0; i < binarray.length * 4; i += 3)
  {
    var triplet = (((binarray[i   >> 2] >> 8 * (3 -  i   %4)) & 0xFF) << 16)
                | (((binarray[i+1 >> 2] >> 8 * (3 - (i+1)%4)) & 0xFF) << 8 )
                |  ((binarray[i+2 >> 2] >> 8 * (3 - (i+2)%4)) & 0xFF);
    for(var j = 0; j < 4; j++)
    {
      if(i * 8 + j * 6 > binarray.length * 32) str += b64pad;
      else str += tab.charAt((triplet >> 6*(3-j)) & 0x3F);
    }
  }
  return str;
}
EOS

}	# End of javascript.

# -----------------------------------------------

sub new
{
	my($class, %arg)	= @_;
	my($self)			= bless({}, $class);

	for my $attr_name ($self -> _standard_keys() )
	{
		my($arg_name) = $attr_name =~ /^_(.*)/;

		if (exists($arg{$arg_name}) )
		{
			$$self{$attr_name} = $arg{$arg_name};
		}
		else
		{
			$$self{$attr_name} = $self -> _default_for($attr_name);
		}
	}

	$self;

}	# End of new.

# -----------------------------------------------

1;

__END__

=head1 NAME

C<Javascript::SHA1> - Calculate the SHA1 digest of a CGI form field

=head1 Synopsis

This is a complete, runnable, tested program.

	#!/usr/bin/perl

	use strict;
	use warnings;

	use CGI;
	use Javascript::SHA1;

	# ------------------

	my($q)	= CGI -> new();
	my($p)	= $q -> param('my_password') || '';
	my($js)	= Javascript::SHA1 -> new();

	print $q -> header(),
      $q -> start_html({script => $js -> javascript('my_password'), title => 'Javascript::SHA1'}),
      $q -> h1({align => 'center'}, 'Javascript::SHA1'),
      "Previous value: $p",
      $q -> br(),
      $q -> start_form({action => $q -> url(), name => 'SHA1'}),
      'Username: ',
      $q -> textfield({name => 'my_username', size => 50}),
      $q -> br(),
      'Password: ',
      $q -> password_field({name => 'my_password', size => 50}),
      $q -> br(),
      'Generate str2hex_sha1: ',
      $q -> submit({onClick => 'return str2hex_sha1()'}),
      $q -> end_form(),
      $q -> end_html();

=head1 Description

C<Javascript::SHA1> is a pure Perl module.

This module allows you to convert user input, eg a password, into the SHA1 digest of that
input.

This means the password itself need never be transmitted across the network - only the SHA1
digest need be transmitted.

=head1 Distributions

This module is available both as a Unix-style distro (*.tgz) and an
ActiveState-style distro (*.ppd). The latter is shipped in a *.zip file.

See http://savage.net.au/Perl-modules.html for details.

See http://savage.net.au/Perl-modules/html/installing-a-module.html for
help on unpacking and installing each type of distro.

=head1 Constructor and initialization

new(...) returns a C<Javascript::SHA1> object.

This is the class's contructor.

Usage: Javascript::SHA1 -> new().

C<new()> does not take any parameters.

=head1 Method: javascript([$name_of_CGI_password_field][, $number_of_CGI_form])

Returns a block of Javascript which you must output as part of your HTML page.

Takes 2 optional parameters:

=over 4

=item The name of the CGI field used to input the password

This field name defaults to 'password'.

=item The number of the CGI form within the HTML page

This field value defaults to 0, which is the first form on the page.

=back

See the Synopsis for one way to do this.

Note: if you pass just 1 parameter, it is assumed to be the name of a field.

=head1 Submitting a CGI Form

To disable this module, simply use a submit button of the form:

	$q -> submit();

To enable the module, use a submit button with an onClick event handler that calls a
Javascript function which converts your CGI password field's value into the SHA1 digest
of that value. Use one of:

=over 4

=item $q -> submit({onClick => 'return str2hex_sha1()'});

Returns a string of length 40.

=item $q -> submit({onClick => 'return str2b64_sha1()'});

Returns a string of length 27.

=item $q -> submit({onClick => 'return str2str_sha1()'});

Returns a string of length 20 (approx :-).

=back

=head1 Example code

See the examples/ directory in the distro.

There is 1 demo file, sha1.cgi.

This is a CGI script identical to the one in the synopsis.

Edit it to suit your circumstances.

=head1 Related Modules

Javascript::MD5.

=head1 Author

C<Javascript::SHA1> was written by Ron Savage I<E<lt>ron@savage.net.auE<gt>> in 2004.

Home page: http://savage.net.au/index.html

=head1 Copyright

Australian copyright (c) 2004, Ron Savage.
	All Programs of mine are 'OSI Certified Open Source Software';
	you can redistribute them and/or modify them under the terms of
	The Artistic License, a copy of which is available at:
	http://www.opensource.org/licenses/index.html

=cut