package Digest::SHA::PurePerl;

require 5.003000;

use strict;
use vars qw($VERSION @ISA @EXPORT @EXPORT_OK);
use integer;
use FileHandle;

$VERSION = '5.48';

require Exporter;
@ISA = qw(Exporter);
@EXPORT_OK = ();		# see "SHA and HMAC-SHA functions" below

# If possible, inherit from Digest::base (which depends on MIME::Base64)

*addfile = \&_Addfile;

eval {
	require MIME::Base64;
	require Digest::base;
	push(@ISA, 'Digest::base');
};
if ($@) {
	*hexdigest = \&_Hexdigest;
	*b64digest = \&_B64digest;
}

# ref. src/sha.c and sha/sha64bit.c from Digest::SHA

my $MAX32 = 0xffffffff;
my $TWO32 = 4294967296;

my $uses64bit = (((1 << 16) << 16) << 16) << 15;


my @H01 = (			# SHA-1 initial hash value
	0x67452301, 0xefcdab89, 0x98badcfe, 0x10325476,
	0xc3d2e1f0
);

my @H0224 = (			# SHA-224 initial hash value
	0xc1059ed8, 0x367cd507, 0x3070dd17, 0xf70e5939,
	0xffc00b31, 0x68581511, 0x64f98fa7, 0xbefa4fa4
);

my @H0256 = (			# SHA-256 initial hash value
	0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a,
	0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19
);

my(@H0384, @H0512);		# filled in later if $uses64bit

# Routines with a "_c_" prefix return Perl code-fragments which are
# eval'ed at initialization.  This technique emulates the behavior
# of the C preprocessor, allowing the optimized transform code from
# Digest::SHA to be more easily translated into Perl.

sub _c_SL32 {			# code to shift $x left by $n bits
	my($x, $n) = @_;
	"($x << $n)";		# even works for 64-bit integers
				# since the upper 32 bits are
				# eventually discarded in _digcpy
}

sub _c_SR32 {			# code to shift $x right by $n bits
	my($x, $n) = @_;
	my $mask = (1 << (32 - $n)) - 1;
	"(($x >> $n) & $mask)";		# "use integer" does arithmetic
					# shift, so clear upper bits
}

sub _c_Ch { my($x, $y, $z) = @_; "($z ^ ($x & ($y ^ $z)))" }
sub _c_Pa { my($x, $y, $z) = @_; "($x ^ $y ^ $z)" }
sub _c_Ma { my($x, $y, $z) = @_; "(($x & $y) | ($z & ($x | $y)))" }

sub _c_ROTR {			# code to rotate $x right by $n bits
	my($x, $n) = @_;
	"(" . _c_SR32($x, $n) . " | " . _c_SL32($x, 32 - $n) . ")";
}

sub _c_ROTL {			# code to rotate $x left by $n bits
	my($x, $n) = @_;
	"(" . _c_SL32($x, $n) . " | " . _c_SR32($x, 32 - $n) . ")";
}

sub _c_SIGMA0 {			# ref. NIST SHA standard
	my($x) = @_;
	"(" . _c_ROTR($x,  2) . " ^ " . _c_ROTR($x, 13) . " ^ " .
		_c_ROTR($x, 22) . ")";
}

sub _c_SIGMA1 {
	my($x) = @_;
	"(" . _c_ROTR($x,  6) . " ^ " . _c_ROTR($x, 11) . " ^ " .
		_c_ROTR($x, 25) . ")";
}

sub _c_sigma0 {
	my($x) = @_;
	"(" . _c_ROTR($x,  7) . " ^ " . _c_ROTR($x, 18) . " ^ " .
		_c_SR32($x,  3) . ")";
}

sub _c_sigma1 {
	my($x) = @_;
	"(" . _c_ROTR($x, 17) . " ^ " . _c_ROTR($x, 19) . " ^ " .
		_c_SR32($x, 10) . ")";
}

sub _c_M1Ch {			# ref. Digest::SHA sha.c (sha1 routine)
	my($a, $b, $c, $d, $e, $k, $w) = @_;
	"$e += " . _c_ROTL($a, 5) . " + " . _c_Ch($b, $c, $d) .
		" + $k + $w; $b = " . _c_ROTL($b, 30) . ";\n";
}

sub _c_M1Pa {
	my($a, $b, $c, $d, $e, $k, $w) = @_;
	"$e += " . _c_ROTL($a, 5) . " + " . _c_Pa($b, $c, $d) .
		" + $k + $w; $b = " . _c_ROTL($b, 30) . ";\n";
}

sub _c_M1Ma {
	my($a, $b, $c, $d, $e, $k, $w) = @_;
	"$e += " . _c_ROTL($a, 5) . " + " . _c_Ma($b, $c, $d) .
		" + $k + $w; $b = " . _c_ROTL($b, 30) . ";\n";
}

sub _c_M11Ch { my($k, $w) = @_; _c_M1Ch('$a', '$b', '$c', '$d', '$e', $k, $w) }
sub _c_M11Pa { my($k, $w) = @_; _c_M1Pa('$a', '$b', '$c', '$d', '$e', $k, $w) }
sub _c_M11Ma { my($k, $w) = @_; _c_M1Ma('$a', '$b', '$c', '$d', '$e', $k, $w) }
sub _c_M12Ch { my($k, $w) = @_; _c_M1Ch('$e', '$a', '$b', '$c', '$d', $k, $w) }
sub _c_M12Pa { my($k, $w) = @_; _c_M1Pa('$e', '$a', '$b', '$c', '$d', $k, $w) }
sub _c_M12Ma { my($k, $w) = @_; _c_M1Ma('$e', '$a', '$b', '$c', '$d', $k, $w) }
sub _c_M13Ch { my($k, $w) = @_; _c_M1Ch('$d', '$e', '$a', '$b', '$c', $k, $w) }
sub _c_M13Pa { my($k, $w) = @_; _c_M1Pa('$d', '$e', '$a', '$b', '$c', $k, $w) }
sub _c_M13Ma { my($k, $w) = @_; _c_M1Ma('$d', '$e', '$a', '$b', '$c', $k, $w) }
sub _c_M14Ch { my($k, $w) = @_; _c_M1Ch('$c', '$d', '$e', '$a', '$b', $k, $w) }
sub _c_M14Pa { my($k, $w) = @_; _c_M1Pa('$c', '$d', '$e', '$a', '$b', $k, $w) }
sub _c_M14Ma { my($k, $w) = @_; _c_M1Ma('$c', '$d', '$e', '$a', '$b', $k, $w) }
sub _c_M15Ch { my($k, $w) = @_; _c_M1Ch('$b', '$c', '$d', '$e', '$a', $k, $w) }
sub _c_M15Pa { my($k, $w) = @_; _c_M1Pa('$b', '$c', '$d', '$e', '$a', $k, $w) }
sub _c_M15Ma { my($k, $w) = @_; _c_M1Ma('$b', '$c', '$d', '$e', '$a', $k, $w) }

sub _c_W11 { my($s) = @_; '$W[' . (($s +  0) & 0xf) . ']' }
sub _c_W12 { my($s) = @_; '$W[' . (($s + 13) & 0xf) . ']' }
sub _c_W13 { my($s) = @_; '$W[' . (($s +  8) & 0xf) . ']' }
sub _c_W14 { my($s) = @_; '$W[' . (($s +  2) & 0xf) . ']' }

sub _c_A1 {
	my($s) = @_;
	my $tmp = _c_W11($s) . " ^ " . _c_W12($s) . " ^ " .
		_c_W13($s) . " ^ " . _c_W14($s);
	"((\$tmp = $tmp), (" . _c_W11($s) . " = " . _c_ROTL('$tmp', 1) . "))";
}

# The following code emulates the "sha1" routine from Digest::SHA sha.c

my $sha1_code = '

my($K1, $K2, $K3, $K4) = (	# SHA-1 constants
	0x5a827999, 0x6ed9eba1, 0x8f1bbcdc, 0xca62c1d6
);

sub _sha1 {
	my($self, $block) = @_;
	my(@W, $a, $b, $c, $d, $e, $tmp);

	@W = unpack("N16", $block);
	($a, $b, $c, $d, $e) = @{$self->{H}};
' .
	_c_M11Ch('$K1', '$W[ 0]'  ) . _c_M12Ch('$K1', '$W[ 1]'  ) .
	_c_M13Ch('$K1', '$W[ 2]'  ) . _c_M14Ch('$K1', '$W[ 3]'  ) .
	_c_M15Ch('$K1', '$W[ 4]'  ) . _c_M11Ch('$K1', '$W[ 5]'  ) .
	_c_M12Ch('$K1', '$W[ 6]'  ) . _c_M13Ch('$K1', '$W[ 7]'  ) .
	_c_M14Ch('$K1', '$W[ 8]'  ) . _c_M15Ch('$K1', '$W[ 9]'  ) .
	_c_M11Ch('$K1', '$W[10]'  ) . _c_M12Ch('$K1', '$W[11]'  ) .
	_c_M13Ch('$K1', '$W[12]'  ) . _c_M14Ch('$K1', '$W[13]'  ) .
	_c_M15Ch('$K1', '$W[14]'  ) . _c_M11Ch('$K1', '$W[15]'  ) .
	_c_M12Ch('$K1', _c_A1( 0) ) . _c_M13Ch('$K1', _c_A1( 1) ) .
	_c_M14Ch('$K1', _c_A1( 2) ) . _c_M15Ch('$K1', _c_A1( 3) ) .
	_c_M11Pa('$K2', _c_A1( 4) ) . _c_M12Pa('$K2', _c_A1( 5) ) .
	_c_M13Pa('$K2', _c_A1( 6) ) . _c_M14Pa('$K2', _c_A1( 7) ) .
	_c_M15Pa('$K2', _c_A1( 8) ) . _c_M11Pa('$K2', _c_A1( 9) ) .
	_c_M12Pa('$K2', _c_A1(10) ) . _c_M13Pa('$K2', _c_A1(11) ) .
	_c_M14Pa('$K2', _c_A1(12) ) . _c_M15Pa('$K2', _c_A1(13) ) .
	_c_M11Pa('$K2', _c_A1(14) ) . _c_M12Pa('$K2', _c_A1(15) ) .
	_c_M13Pa('$K2', _c_A1( 0) ) . _c_M14Pa('$K2', _c_A1( 1) ) .
	_c_M15Pa('$K2', _c_A1( 2) ) . _c_M11Pa('$K2', _c_A1( 3) ) .
	_c_M12Pa('$K2', _c_A1( 4) ) . _c_M13Pa('$K2', _c_A1( 5) ) .
	_c_M14Pa('$K2', _c_A1( 6) ) . _c_M15Pa('$K2', _c_A1( 7) ) .
	_c_M11Ma('$K3', _c_A1( 8) ) . _c_M12Ma('$K3', _c_A1( 9) ) .
	_c_M13Ma('$K3', _c_A1(10) ) . _c_M14Ma('$K3', _c_A1(11) ) .
	_c_M15Ma('$K3', _c_A1(12) ) . _c_M11Ma('$K3', _c_A1(13) ) .
	_c_M12Ma('$K3', _c_A1(14) ) . _c_M13Ma('$K3', _c_A1(15) ) .
	_c_M14Ma('$K3', _c_A1( 0) ) . _c_M15Ma('$K3', _c_A1( 1) ) .
	_c_M11Ma('$K3', _c_A1( 2) ) . _c_M12Ma('$K3', _c_A1( 3) ) .
	_c_M13Ma('$K3', _c_A1( 4) ) . _c_M14Ma('$K3', _c_A1( 5) ) .
	_c_M15Ma('$K3', _c_A1( 6) ) . _c_M11Ma('$K3', _c_A1( 7) ) .
	_c_M12Ma('$K3', _c_A1( 8) ) . _c_M13Ma('$K3', _c_A1( 9) ) .
	_c_M14Ma('$K3', _c_A1(10) ) . _c_M15Ma('$K3', _c_A1(11) ) .
	_c_M11Pa('$K4', _c_A1(12) ) . _c_M12Pa('$K4', _c_A1(13) ) .
	_c_M13Pa('$K4', _c_A1(14) ) . _c_M14Pa('$K4', _c_A1(15) ) .
	_c_M15Pa('$K4', _c_A1( 0) ) . _c_M11Pa('$K4', _c_A1( 1) ) .
	_c_M12Pa('$K4', _c_A1( 2) ) . _c_M13Pa('$K4', _c_A1( 3) ) .
	_c_M14Pa('$K4', _c_A1( 4) ) . _c_M15Pa('$K4', _c_A1( 5) ) .
	_c_M11Pa('$K4', _c_A1( 6) ) . _c_M12Pa('$K4', _c_A1( 7) ) .
	_c_M13Pa('$K4', _c_A1( 8) ) . _c_M14Pa('$K4', _c_A1( 9) ) .
	_c_M15Pa('$K4', _c_A1(10) ) . _c_M11Pa('$K4', _c_A1(11) ) .
	_c_M12Pa('$K4', _c_A1(12) ) . _c_M13Pa('$K4', _c_A1(13) ) .
	_c_M14Pa('$K4', _c_A1(14) ) . _c_M15Pa('$K4', _c_A1(15) ) .

'	$self->{H}->[0] += $a; $self->{H}->[1] += $b; $self->{H}->[2] += $c;
	$self->{H}->[3] += $d; $self->{H}->[4] += $e;
}
';

eval($sha1_code);

sub _c_M2 {			# ref. Digest::SHA sha.c (sha256 routine)
	my($a, $b, $c, $d, $e, $f, $g, $h, $w) = @_;
	"\$T1 = $h + " . _c_SIGMA1($e) . " + " . _c_Ch($e, $f, $g) .
		" + \$K256[\$i++] + $w; $h = \$T1 + " . _c_SIGMA0($a) .
		" + " . _c_Ma($a, $b, $c) . "; $d += \$T1;\n";
}

sub _c_M21 { _c_M2('$a', '$b', '$c', '$d', '$e', '$f', '$g', '$h', $_[0]) }
sub _c_M22 { _c_M2('$h', '$a', '$b', '$c', '$d', '$e', '$f', '$g', $_[0]) }
sub _c_M23 { _c_M2('$g', '$h', '$a', '$b', '$c', '$d', '$e', '$f', $_[0]) }
sub _c_M24 { _c_M2('$f', '$g', '$h', '$a', '$b', '$c', '$d', '$e', $_[0]) }
sub _c_M25 { _c_M2('$e', '$f', '$g', '$h', '$a', '$b', '$c', '$d', $_[0]) }
sub _c_M26 { _c_M2('$d', '$e', '$f', '$g', '$h', '$a', '$b', '$c', $_[0]) }
sub _c_M27 { _c_M2('$c', '$d', '$e', '$f', '$g', '$h', '$a', '$b', $_[0]) }
sub _c_M28 { _c_M2('$b', '$c', '$d', '$e', '$f', '$g', '$h', '$a', $_[0]) }

sub _c_W21 { my($s) = @_; '$W[' . (($s +  0) & 0xf) . ']' }
sub _c_W22 { my($s) = @_; '$W[' . (($s + 14) & 0xf) . ']' }
sub _c_W23 { my($s) = @_; '$W[' . (($s +  9) & 0xf) . ']' }
sub _c_W24 { my($s) = @_; '$W[' . (($s +  1) & 0xf) . ']' }

sub _c_A2 {
	my($s) = @_;
	"(" . _c_W21($s) . " += " . _c_sigma1(_c_W22($s)) . " + " .
		_c_W23($s) . " + " . _c_sigma0(_c_W24($s)) . ")";
}

# The following code emulates the "sha256" routine from Digest::SHA sha.c

my $sha256_code = '

my @K256 = (			# SHA-224/256 constants
	0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
	0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
	0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
	0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
	0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
	0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
	0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
	0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
	0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
	0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
	0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
	0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
	0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
	0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
	0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
	0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
);

sub _sha256 {
	my($self, $block) = @_;
	my(@W, $a, $b, $c, $d, $e, $f, $g, $h, $i, $T1);

	@W = unpack("N16", $block);
	($a, $b, $c, $d, $e, $f, $g, $h) = @{$self->{H}};
' .
	_c_M21('$W[ 0]' ) . _c_M22('$W[ 1]' ) . _c_M23('$W[ 2]' ) .
	_c_M24('$W[ 3]' ) . _c_M25('$W[ 4]' ) . _c_M26('$W[ 5]' ) .
	_c_M27('$W[ 6]' ) . _c_M28('$W[ 7]' ) . _c_M21('$W[ 8]' ) .
	_c_M22('$W[ 9]' ) . _c_M23('$W[10]' ) . _c_M24('$W[11]' ) .
	_c_M25('$W[12]' ) . _c_M26('$W[13]' ) . _c_M27('$W[14]' ) .
	_c_M28('$W[15]' ) .
	_c_M21(_c_A2( 0)) . _c_M22(_c_A2( 1)) . _c_M23(_c_A2( 2)) .
	_c_M24(_c_A2( 3)) . _c_M25(_c_A2( 4)) . _c_M26(_c_A2( 5)) .
	_c_M27(_c_A2( 6)) . _c_M28(_c_A2( 7)) . _c_M21(_c_A2( 8)) .
	_c_M22(_c_A2( 9)) . _c_M23(_c_A2(10)) . _c_M24(_c_A2(11)) .
	_c_M25(_c_A2(12)) . _c_M26(_c_A2(13)) . _c_M27(_c_A2(14)) .
	_c_M28(_c_A2(15)) . _c_M21(_c_A2( 0)) . _c_M22(_c_A2( 1)) .
	_c_M23(_c_A2( 2)) . _c_M24(_c_A2( 3)) . _c_M25(_c_A2( 4)) .
	_c_M26(_c_A2( 5)) . _c_M27(_c_A2( 6)) . _c_M28(_c_A2( 7)) .
	_c_M21(_c_A2( 8)) . _c_M22(_c_A2( 9)) . _c_M23(_c_A2(10)) .
	_c_M24(_c_A2(11)) . _c_M25(_c_A2(12)) . _c_M26(_c_A2(13)) .
	_c_M27(_c_A2(14)) . _c_M28(_c_A2(15)) . _c_M21(_c_A2( 0)) .
	_c_M22(_c_A2( 1)) . _c_M23(_c_A2( 2)) . _c_M24(_c_A2( 3)) .
	_c_M25(_c_A2( 4)) . _c_M26(_c_A2( 5)) . _c_M27(_c_A2( 6)) .
	_c_M28(_c_A2( 7)) . _c_M21(_c_A2( 8)) . _c_M22(_c_A2( 9)) .
	_c_M23(_c_A2(10)) . _c_M24(_c_A2(11)) . _c_M25(_c_A2(12)) .
	_c_M26(_c_A2(13)) . _c_M27(_c_A2(14)) . _c_M28(_c_A2(15)) .

'	$self->{H}->[0] += $a; $self->{H}->[1] += $b; $self->{H}->[2] += $c;
	$self->{H}->[3] += $d; $self->{H}->[4] += $e; $self->{H}->[5] += $f;
	$self->{H}->[6] += $g; $self->{H}->[7] += $h;
}
';

eval($sha256_code);

sub _sha512_placeholder { return }
my $sha512 = \&_sha512_placeholder;

my $_64bit_code = '

my $w_flag;

BEGIN {
	$w_flag = $^W;		# suppress compiler warnings about
	$^W = 0;		# non-portable 64-bit constants
}

my @K512 = (
	0x428a2f98d728ae22, 0x7137449123ef65cd, 0xb5c0fbcfec4d3b2f,
	0xe9b5dba58189dbbc, 0x3956c25bf348b538, 0x59f111f1b605d019,
	0x923f82a4af194f9b, 0xab1c5ed5da6d8118, 0xd807aa98a3030242,
	0x12835b0145706fbe, 0x243185be4ee4b28c, 0x550c7dc3d5ffb4e2,
	0x72be5d74f27b896f, 0x80deb1fe3b1696b1, 0x9bdc06a725c71235,
	0xc19bf174cf692694, 0xe49b69c19ef14ad2, 0xefbe4786384f25e3,
	0x0fc19dc68b8cd5b5, 0x240ca1cc77ac9c65, 0x2de92c6f592b0275,
	0x4a7484aa6ea6e483, 0x5cb0a9dcbd41fbd4, 0x76f988da831153b5,
	0x983e5152ee66dfab, 0xa831c66d2db43210, 0xb00327c898fb213f,
	0xbf597fc7beef0ee4, 0xc6e00bf33da88fc2, 0xd5a79147930aa725,
	0x06ca6351e003826f, 0x142929670a0e6e70, 0x27b70a8546d22ffc,
	0x2e1b21385c26c926, 0x4d2c6dfc5ac42aed, 0x53380d139d95b3df,
	0x650a73548baf63de, 0x766a0abb3c77b2a8, 0x81c2c92e47edaee6,
	0x92722c851482353b, 0xa2bfe8a14cf10364, 0xa81a664bbc423001,
	0xc24b8b70d0f89791, 0xc76c51a30654be30, 0xd192e819d6ef5218,
	0xd69906245565a910, 0xf40e35855771202a, 0x106aa07032bbd1b8,
	0x19a4c116b8d2d0c8, 0x1e376c085141ab53, 0x2748774cdf8eeb99,
	0x34b0bcb5e19b48a8, 0x391c0cb3c5c95a63, 0x4ed8aa4ae3418acb,
	0x5b9cca4f7763e373, 0x682e6ff3d6b2b8a3, 0x748f82ee5defb2fc,
	0x78a5636f43172f60, 0x84c87814a1f0ab72, 0x8cc702081a6439ec,
	0x90befffa23631e28, 0xa4506cebde82bde9, 0xbef9a3f7b2c67915,
	0xc67178f2e372532b, 0xca273eceea26619c, 0xd186b8c721c0c207,
	0xeada7dd6cde0eb1e, 0xf57d4f7fee6ed178, 0x06f067aa72176fba,
	0x0a637dc5a2c898a6, 0x113f9804bef90dae, 0x1b710b35131c471b,
	0x28db77f523047d84, 0x32caab7b40c72493, 0x3c9ebe0a15c9bebc,
	0x431d67c49c100d4c, 0x4cc5d4becb3e42b6, 0x597f299cfc657e2a,
	0x5fcb6fab3ad6faec, 0x6c44198c4a475817);

@H0384 = (
	0xcbbb9d5dc1059ed8, 0x629a292a367cd507, 0x9159015a3070dd17,
	0x152fecd8f70e5939, 0x67332667ffc00b31, 0x8eb44a8768581511,
	0xdb0c2e0d64f98fa7, 0x47b5481dbefa4fa4);

@H0512 = (
	0x6a09e667f3bcc908, 0xbb67ae8584caa73b, 0x3c6ef372fe94f82b,
	0xa54ff53a5f1d36f1, 0x510e527fade682d1, 0x9b05688c2b3e6c1f,
	0x1f83d9abfb41bd6b, 0x5be0cd19137e2179);

BEGIN { $^W = $w_flag }		# restore prior warning state

sub _c_SL64 { my($x, $n) = @_; "($x << $n)" }

sub _c_SR64 {
	my($x, $n) = @_;
	my $mask = (1 << (64 - $n)) - 1;
	"(($x >> $n) & $mask)";
}

sub _c_ROTRQ {
	my($x, $n) = @_;
	"(" . _c_SR64($x, $n) . " | " . _c_SL64($x, 64 - $n) . ")";
}

sub _c_SIGMAQ0 {
	my($x) = @_;
	"(" . _c_ROTRQ($x, 28) . " ^ " .  _c_ROTRQ($x, 34) . " ^ " .
		_c_ROTRQ($x, 39) . ")";
}

sub _c_SIGMAQ1 {
	my($x) = @_;
	"(" . _c_ROTRQ($x, 14) . " ^ " .  _c_ROTRQ($x, 18) . " ^ " .
		_c_ROTRQ($x, 41) . ")";
}

sub _c_sigmaQ0 {
	my($x) = @_;
	"(" . _c_ROTRQ($x, 1) . " ^ " .  _c_ROTRQ($x, 8) . " ^ " .
		_c_SR64($x, 7) . ")";
}

sub _c_sigmaQ1 {
	my($x) = @_;
	"(" . _c_ROTRQ($x, 19) . " ^ " .  _c_ROTRQ($x, 61) . " ^ " .
		_c_SR64($x, 6) . ")";
}

my $sha512_code = q/
sub _sha512 {
	my($self, $block) = @_;
	my(@N, @W, $a, $b, $c, $d, $e, $f, $g, $h, $T1, $T2);

	@N = unpack("N32", $block);
	($a, $b, $c, $d, $e, $f, $g, $h) = @{$self->{H}};
	for ( 0 .. 15) { $W[$_] = (($N[2*$_] << 16) << 16) | $N[2*$_+1] }
	for (16 .. 79) { $W[$_] = / .
		_c_sigmaQ1(q/$W[$_- 2]/) . q/ + $W[$_- 7] + / .
		_c_sigmaQ0(q/$W[$_-15]/) . q/ + $W[$_-16] }
	for ( 0 .. 79) {
		$T1 = $h + / . _c_SIGMAQ1(q/$e/) .
			q/ + (($g) ^ (($e) & (($f) ^ ($g)))) +
				$K512[$_] + $W[$_];
		$T2 = / . _c_SIGMAQ0(q/$a/) .
			q/ + ((($a) & ($b)) | (($c) & (($a) | ($b))));
		$h = $g; $g = $f; $f = $e; $e = $d + $T1;
		$d = $c; $c = $b; $b = $a; $a = $T1 + $T2;
	}
	$self->{H}->[0] += $a; $self->{H}->[1] += $b; $self->{H}->[2] += $c;
	$self->{H}->[3] += $d; $self->{H}->[4] += $e; $self->{H}->[5] += $f;
	$self->{H}->[6] += $g; $self->{H}->[7] += $h;
}
/;

eval($sha512_code);
$sha512 = \&_sha512;

';

eval($_64bit_code) if $uses64bit;

sub _SETBIT {
	my($self, $pos) = @_;
	my @c = unpack("C*", $self->{block});
	$c[$pos >> 3] = 0x00 unless defined $c[$pos >> 3];
	$c[$pos >> 3] |= (0x01 << (7 - $pos % 8));
	$self->{block} = pack("C*", @c);
}

sub _CLRBIT {
	my($self, $pos) = @_;
	my @c = unpack("C*", $self->{block});
	$c[$pos >> 3] = 0x00 unless defined $c[$pos >> 3];
	$c[$pos >> 3] &= ~(0x01 << (7 - $pos % 8));
	$self->{block} = pack("C*", @c);
}

sub _BYTECNT {
	my($bitcnt) = @_;
	$bitcnt > 0 ? 1 + (($bitcnt - 1) >> 3) : 0;
}

sub _digcpy {
	my($self) = @_;
	my @dig;
	for (@{$self->{H}}) {
		push(@dig, (($_>>16)>>16) & $MAX32) if $self->{alg} >= 384;
		push(@dig, $_ & $MAX32);
	}
	$self->{digest} = pack("N" . ($self->{digestlen}>>2), @dig);
}

sub _sharewind {
	my($self) = @_;
	my $alg = $self->{alg};
	$self->{block} = ""; $self->{blockcnt} = 0;
	$self->{blocksize} = $alg <= 256 ? 512 : 1024;
	for (qw(lenll lenlh lenhl lenhh)) { $self->{$_} = 0 }
	$self->{digestlen} = $alg == 1 ? 20 : $alg/8;
	if    ($alg == 1)   { $self->{sha} = \&_sha1;   $self->{H} = [@H01]   }
	elsif ($alg == 224) { $self->{sha} = \&_sha256; $self->{H} = [@H0224] }
	elsif ($alg == 256) { $self->{sha} = \&_sha256; $self->{H} = [@H0256] }
	elsif ($alg == 384) { $self->{sha} = $sha512;   $self->{H} = [@H0384] }
	elsif ($alg == 512) { $self->{sha} = $sha512;   $self->{H} = [@H0512] }
	push(@{$self->{H}}, 0) while scalar(@{$self->{H}}) < 8;
	$self;
}

sub _shaopen {
	my($alg) = @_;
	my($self);
	return unless grep { $alg == $_ } (1, 224, 256, 384, 512);
	return if ($alg >= 384 && !$uses64bit);
	$self->{alg} = $alg;
	_sharewind($self);
}

sub _shadirect {
	my($bitstr, $bitcnt, $self) = @_;
	my $savecnt = $bitcnt;
	my $offset = 0;
	my $blockbytes = $self->{blocksize} >> 3;
	while ($bitcnt >= $self->{blocksize}) {
		&{$self->{sha}}($self, substr($bitstr, $offset, $blockbytes));
		$offset += $blockbytes;
		$bitcnt -= $self->{blocksize};
	}
	if ($bitcnt > 0) {
		$self->{block} = substr($bitstr, $offset, _BYTECNT($bitcnt));
		$self->{blockcnt} = $bitcnt;
	}
	$savecnt;
}

sub _shabytes {
	my($bitstr, $bitcnt, $self) = @_;
	my($numbits);
	my $savecnt = $bitcnt;
	if ($self->{blockcnt} + $bitcnt >= $self->{blocksize}) {
		$numbits = $self->{blocksize} - $self->{blockcnt};
		$self->{block} .= substr($bitstr, 0, $numbits >> 3);
		$bitcnt -= $numbits;
		$bitstr = substr($bitstr, $numbits >> 3, _BYTECNT($bitcnt));
		&{$self->{sha}}($self, $self->{block});
		$self->{block} = "";
		$self->{blockcnt} = 0;
		_shadirect($bitstr, $bitcnt, $self);
	}
	else {
		$self->{block} .= substr($bitstr, 0, _BYTECNT($bitcnt));
		$self->{blockcnt} += $bitcnt;
	}
	$savecnt;
}

sub _shabits {
	my($bitstr, $bitcnt, $self) = @_;
	my($i, @buf);
	my $numbytes = _BYTECNT($bitcnt);
	my $savecnt = $bitcnt;
	my $gap = 8 - $self->{blockcnt} % 8;
	my @c = unpack("C*", $self->{block});
	my @b = unpack("C" . $numbytes, $bitstr);
	$c[$self->{blockcnt}>>3] &= (~0 << $gap);
	$c[$self->{blockcnt}>>3] |= $b[0] >> (8 - $gap);
	$self->{block} = pack("C*", @c);
	$self->{blockcnt} += ($bitcnt < $gap) ? $bitcnt : $gap;
	return($savecnt) if $bitcnt < $gap;
	if ($self->{blockcnt} == $self->{blocksize}) {
		&{$self->{sha}}($self, $self->{block});
		$self->{block} = "";
		$self->{blockcnt} = 0;
	}
	return($savecnt) if ($bitcnt -= $gap) == 0;
	for ($i = 0; $i < $numbytes - 1; $i++) {
		$buf[$i] = (($b[$i] << $gap) & 0xff) | ($b[$i+1] >> (8 - $gap));
	}
	$buf[$numbytes-1] = ($b[$numbytes-1] << $gap) & 0xff;
	_shabytes(pack("C*", @buf), $bitcnt, $self);
	$savecnt;
}

sub _shawrite {
	my($bitstr, $bitcnt, $self) = @_;
	return(0) unless $bitcnt > 0;
	no integer;
	if (($self->{lenll} += $bitcnt) >= $TWO32) {
		$self->{lenll} -= $TWO32;
		if (++$self->{lenlh} >= $TWO32) {
			$self->{lenlh} -= $TWO32;
			if (++$self->{lenhl} >= $TWO32) {
				$self->{lenhl} -= $TWO32;
				if (++$self->{lenhh} >= $TWO32) {
					$self->{lenhh} -= $TWO32;
				}
			}
		}
	}
	use integer;
	my $blockcnt = $self->{blockcnt};
	return(_shadirect($bitstr, $bitcnt, $self)) if $blockcnt == 0;
	return(_shabytes ($bitstr, $bitcnt, $self)) if $blockcnt % 8 == 0;
	return(_shabits  ($bitstr, $bitcnt, $self));
}

sub _shafinish {
	my($self) = @_;
	my $LENPOS = $self->{alg} <= 256 ? 448 : 896;
	_SETBIT($self, $self->{blockcnt}++);
	while ($self->{blockcnt} > $LENPOS) {
		if ($self->{blockcnt} < $self->{blocksize}) {
			_CLRBIT($self, $self->{blockcnt}++);
		}
		else {
			&{$self->{sha}}($self, $self->{block});
			$self->{block} = "";
			$self->{blockcnt} = 0;
		}
	}
	while ($self->{blockcnt} < $LENPOS) {
		_CLRBIT($self, $self->{blockcnt}++);
	}
	if ($self->{blocksize} > 512) {
		$self->{block} .= pack("N", $self->{lenhh} & $MAX32);
		$self->{block} .= pack("N", $self->{lenhl} & $MAX32);
	}
	$self->{block} .= pack("N", $self->{lenlh} & $MAX32);
	$self->{block} .= pack("N", $self->{lenll} & $MAX32);
	&{$self->{sha}}($self, $self->{block});
}

sub _shadigest { my($self) = @_; _digcpy($self); $self->{digest} }

sub _shahex {
	my($self) = @_;
	_digcpy($self);
	join("", unpack("H*", $self->{digest}));
}

sub _shabase64 {
	my($self) = @_;
	_digcpy($self);
	my $b64 = pack("u", $self->{digest});
	$b64 =~ s/^.//mg;
	$b64 =~ s/\n//g;
	$b64 =~ tr|` -_|AA-Za-z0-9+/|;
	my $numpads = (3 - length($self->{digest}) % 3) % 3;
	$b64 =~ s/.{$numpads}$// if $numpads;
	$b64;
}

sub _shadsize { my($self) = @_; $self->{digestlen} }

sub _shacpy {
	my($to, $from) = @_;
	$to->{alg} = $from->{alg};
	$to->{sha} = $from->{sha};
	$to->{H} = [@{$from->{H}}];
	$to->{block} = $from->{block};
	$to->{blockcnt} = $from->{blockcnt};
	$to->{blocksize} = $from->{blocksize};
	for (qw(lenhh lenhl lenlh lenll)) { $to->{$_} = $from->{$_} }
	$to->{digestlen} = $from->{digestlen};
	$to;
}

sub _shadup { my($self) = @_; my($copy); _shacpy($copy, $self) }

sub _shadump {
	my $file = shift;
	$file = "-" if (!defined($file) || $file eq "");

	my $fh = FileHandle->new($file, "w") or return;
	my $self = shift;
	my $is32bit = $self->{alg} <= 256;
	my $fmt = $is32bit ? ":%08x" : ":%016x";

	printf $fh "alg:%d\n", $self->{alg};

	printf $fh "H";
	for (@{$self->{H}}) { printf $fh $fmt, $is32bit ? $_ & $MAX32 : $_ }

	printf $fh "\nblock";
	my @c = unpack("C*", $self->{block});
	push(@c, 0x00) while scalar(@c) < ($self->{blocksize} >> 3);
	for (@c) { printf $fh ":%02x", $_ }

	printf $fh "\nblockcnt:%u\n", $self->{blockcnt};

	printf $fh "lenhh:%lu\n", $self->{lenhh} & $MAX32;
	printf $fh "lenhl:%lu\n", $self->{lenhl} & $MAX32;
	printf $fh "lenlh:%lu\n", $self->{lenlh} & $MAX32;
	printf $fh "lenll:%lu\n", $self->{lenll} & $MAX32;

	close($fh);
	$self;
}

sub _match {
	my($fh, $tag) = @_;
	my @f;
	while (<$fh>) {
		s/^\s+//;
		s/\s+$//;
		next if (/^(#|$)/);
		@f = split(/[:\s]+/);
		last;
	}
	shift(@f) eq $tag or return;
	return(@f);
}

sub _shaload {
	my $file = shift;
	$file = "-" if (!defined($file) || $file eq "");

	my $fh = FileHandle->new($file, "r") or return;

	my @f = _match($fh, "alg") or return;
	my $self = _shaopen(shift(@f)) or return;

	@f = _match($fh, "H") or return;
	my $numxdigits = $self->{alg} <= 256 ? 8 : 16;
	for (@f) { $_ = "0" . $_ while length($_) < $numxdigits }
	for (@f) { $_ = substr($_, 1) while length($_) > $numxdigits }
	@{$self->{H}} = map { $self->{alg} <= 256 ? hex($_) :
		((hex(substr($_, 0, 8)) << 16) << 16) |
		hex(substr($_, 8)) } @f;

	@f = _match($fh, "block") or return;
	for (@f) { $self->{block} .= chr(hex($_)) }

	@f = _match($fh, "blockcnt") or return;
	$self->{blockcnt} = shift(@f);
	$self->{block} = substr($self->{block},0,_BYTECNT($self->{blockcnt}));

	@f = _match($fh, "lenhh") or return;
	$self->{lenhh} = shift(@f);
	@f = _match($fh, "lenhl") or return;
	$self->{lenhl} = shift(@f);
	@f = _match($fh, "lenlh") or return;
	$self->{lenlh} = shift(@f);
	@f = _match($fh, "lenll") or return;
	$self->{lenll} = shift(@f);

	close($fh);
	$self;
}

# ref. src/hmac.c from Digest::SHA

sub _hmacopen {
	my($alg, $key) = @_;
	my($self);
	$self->{isha} = _shaopen($alg) or return;
	$self->{osha} = _shaopen($alg) or return;
	if (length($key) > $self->{osha}->{blocksize} >> 3) {
		$self->{ksha} = _shaopen($alg) or return;
		_shawrite($key, length($key) << 3, $self->{ksha});
		_shafinish($self->{ksha});
		$key = _shadigest($self->{ksha});
	}
	$key .= chr(0x00)
		while length($key) < $self->{osha}->{blocksize} >> 3;
	my @k = unpack("C*", $key);
	for (@k) { $_ ^= 0x5c }
	_shawrite(pack("C*", @k), $self->{osha}->{blocksize}, $self->{osha});
	for (@k) { $_ ^= (0x5c ^ 0x36) }
	_shawrite(pack("C*", @k), $self->{isha}->{blocksize}, $self->{isha});
	$self;
}

sub _hmacwrite {
	my($bitstr, $bitcnt, $self) = @_;
	_shawrite($bitstr, $bitcnt, $self->{isha});
}

sub _hmacfinish {
	my($self) = @_;
	_shafinish($self->{isha});
	_shawrite(_shadigest($self->{isha}),
			$self->{isha}->{digestlen} << 3, $self->{osha});
	_shafinish($self->{osha});
}

sub _hmacdigest { my($self) = @_; _shadigest($self->{osha}) }
sub _hmachex    { my($self) = @_; _shahex($self->{osha})    }
sub _hmacbase64 { my($self) = @_; _shabase64($self->{osha}) }

# SHA and HMAC-SHA functions

my @suffix_extern = ("", "_hex", "_base64");
my @suffix_intern = ("digest", "hex", "base64");

my($i, $alg);
for $alg (1, 224, 256, 384, 512) {
	for $i (0 .. 2) {
		my $fcn = 'sub sha' . $alg . $suffix_extern[$i] . ' {
			my $state = _shaopen(' . $alg . ') or return;
			for (@_) { _shawrite($_, length($_) << 3, $state) }
			_shafinish($state);
			_sha' . $suffix_intern[$i] . '($state);
		}';
		eval($fcn);
		push(@EXPORT_OK, 'sha' . $alg . $suffix_extern[$i]);
		$fcn = 'sub hmac_sha' . $alg . $suffix_extern[$i] . ' {
			my $state = _hmacopen(' . $alg . ', pop(@_)) or return;
			for (@_) { _hmacwrite($_, length($_) << 3, $state) }
			_hmacfinish($state);
			_hmac' . $suffix_intern[$i] . '($state);
		}';
		eval($fcn);
		push(@EXPORT_OK, 'hmac_sha' . $alg . $suffix_extern[$i]);
	}
}

# OOP methods

sub hashsize  { my $self = shift; _shadsize($self) << 3 }
sub algorithm { my $self = shift; $self->{alg} }

sub add {
	my $self = shift;
	for (@_) { _shawrite($_, length($_) << 3, $self) }
	$self;
}

sub digest {
	my $self = shift;
	_shafinish($self);
	my $rsp = _shadigest($self);
	_sharewind($self);
	$rsp;
}

sub _Hexdigest {
	my $self = shift;
	_shafinish($self);
	my $rsp = _shahex($self);
	_sharewind($self);
	$rsp;
}

sub _B64digest {
	my $self = shift;
	_shafinish($self);
	my $rsp = _shabase64($self);
	_sharewind($self);
	$rsp;
}

sub new {
	my($class, $alg) = @_;
	$alg =~ s/\D+//g if defined $alg;
	if (ref($class)) {	# instance method
		unless (defined($alg) && ($alg != $class->algorithm)) {
			_sharewind($class);
			return($class);
		}
		my $self = _shaopen($alg) or return;
		return(_shacpy($class, $self));
	}
	$alg = 1 unless defined $alg;
	my $self = _shaopen($alg) or return;
	bless($self, $class);
	$self;
}

sub clone {
	my $self = shift;
	my $copy = _shadup($self) or return;
	bless($copy, ref($self));
	return($copy);
}

*reset = \&new;

sub add_bits {
	my($self, $data, $nbits) = @_;
	unless (defined $nbits) {
		$nbits = length($data);
		$data = pack("B*", $data);
	}
	_shawrite($data, $nbits, $self);
	return($self);
}

sub _bail {
	my $msg = shift;

        require Carp;
        Carp::croak("$msg: $!");
}

sub _addfile {
    my ($self, $handle) = @_;

    my $n;
    my $buf = "";

    while (($n = read($handle, $buf, 4096))) {
        $self->add($buf);
    }
    _bail("Read failed") unless defined $n;

    $self;
}

sub _Addfile {
	my ($self, $file, $mode) = @_;

	return(_addfile($self, $file)) unless ref(\$file) eq 'SCALAR';

	$mode = defined($mode) ? $mode : "";
	my ($binary, $portable) = map { $_ eq $mode } ("b", "p");
	my $text = -T $file;

	local *FH;
		# protect any leading or trailing whitespace in $file;
		# otherwise, 2-arg "open" will ignore them
	$file =~ s#^(\s)#./$1#;
	open(FH, "< $file\0") or _bail("Open failed");
	binmode(FH) if $binary || $portable;

	unless ($portable && $text) {
		$self->_addfile(*FH);
		close(FH);
		return($self);
	}

	my ($n1, $n2);
	my ($buf1, $buf2) = ("", "");

	while (($n1 = read(FH, $buf1, 4096))) {
		while (substr($buf1, -1) eq "\015") {
			$n2 = read(FH, $buf2, 4096);
			_bail("Read failed") unless defined $n2;
			last unless $n2;
			$buf1 .= $buf2;
		}
		$buf1 =~ s/\015?\015\012/\012/g; 	# DOS/Windows
		$buf1 =~ s/\015/\012/g;          	# early MacOS
		$self->add($buf1);
	}
	_bail("Read failed") unless defined $n1;
	close(FH);

	$self;
}

sub dump {
	my $self = shift;
	my $file = shift || "";

	_shadump($file, $self) or return;
	return($self);
}

sub load {
	my $class = shift;
	my $file = shift || "";
	if (ref($class)) {	# instance method
		my $self = _shaload($file) or return;
		return(_shacpy($class, $self));
	}
	my $self = _shaload($file) or return;
	bless($self, $class);
	return($self);
}

1;
__END__

=head1 NAME

Digest::SHA::PurePerl - Perl implementation of SHA-1/224/256/384/512

=head1 SYNOPSIS

In programs:

		# Functional interface

	use Digest::SHA::PurePerl qw(sha1 sha1_hex sha1_base64 ...);

	$digest = sha1($data);
	$digest = sha1_hex($data);
	$digest = sha1_base64($data);

	$digest = sha256($data);
	$digest = sha384_hex($data);
	$digest = sha512_base64($data);

		# Object-oriented

	use Digest::SHA::PurePerl;

	$sha = Digest::SHA::PurePerl->new($alg);

	$sha->add($data);		# feed data into stream

	$sha->addfile(*F);
        $sha->addfile($filename);

	$sha->add_bits($bits);
	$sha->add_bits($data, $nbits);

	$sha_copy = $sha->clone;	# if needed, make copy of
	$sha->dump($file);		#	current digest state,
	$sha->load($file);		#	or save it on disk

	$digest = $sha->digest;		# compute digest
	$digest = $sha->hexdigest;
	$digest = $sha->b64digest;

From the command line:

	$ shasum files

	$ shasum --help

=head1 SYNOPSIS (HMAC-SHA)

		# Functional interface only

	use Digest::SHA::PurePerl qw(hmac_sha1 hmac_sha1_hex ...);

	$digest = hmac_sha1($data, $key);
	$digest = hmac_sha224_hex($data, $key);
	$digest = hmac_sha256_base64($data, $key);

=head1 ABSTRACT

Digest::SHA::PurePerl is a complete implementation of the NIST
Secure Hash Standard.  It gives Perl programmers a convenient way
to calculate SHA-1, SHA-224, SHA-256, SHA-384, and SHA-512 message
digests.  The module can handle all types of input, including
partial-byte data.

=head1 DESCRIPTION

Digest::SHA::PurePerl is written entirely in Perl.  If your platform
has a C compiler, you should install the functionally equivalent
(but much faster) L<Digest::SHA> module.

The programming interface is easy to use: it's the same one found
in CPAN's L<Digest> module.  So, if your applications currently
use L<Digest::MD5> and you'd prefer the stronger security of SHA,
it's a simple matter to convert them.

The interface provides two ways to calculate digests:  all-at-once,
or in stages.  To illustrate, the following short program computes
the SHA-256 digest of "hello world" using each approach:

	use Digest::SHA::PurePerl qw(sha256_hex);

	$data = "hello world";
	@frags = split(//, $data);

	# all-at-once (Functional style)
	$digest1 = sha256_hex($data);

	# in-stages (OOP style)
	$state = Digest::SHA::PurePerl->new(256);
	for (@frags) { $state->add($_) }
	$digest2 = $state->hexdigest;

	print $digest1 eq $digest2 ?
		"whew!\n" : "oops!\n";

To calculate the digest of an n-bit message where I<n> is not a
multiple of 8, use the I<add_bits()> method.  For example, consider
the 446-bit message consisting of the bit-string "110" repeated
148 times, followed by "11".  Here's how to display its SHA-1
digest:

	use Digest::SHA::PurePerl;
	$bits = "110" x 148 . "11";
	$sha = Digest::SHA::PurePerl->new(1)->add_bits($bits);
	print $sha->hexdigest, "\n";

Note that for larger bit-strings, it's more efficient to use the
two-argument version I<add_bits($data, $nbits)>, where I<$data> is
in the customary packed binary format used for Perl strings.

The module also lets you save intermediate SHA states to disk, or
display them on standard output.  The I<dump()> method generates
portable, human-readable text describing the current state of
computation.  You can subsequently retrieve the file with I<load()>
to resume where the calculation left off.

To see what a state description looks like, just run the following:

	use Digest::SHA::PurePerl;
	Digest::SHA::PurePerl->new->add("Shaw" x 1962)->dump;

As an added convenience, the Digest::SHA::PurePerl module offers
routines to calculate keyed hashes using the HMAC-SHA-1/224/256/384/512
algorithms.  These services exist in functional form only, and
mimic the style and behavior of the I<sha()>, I<sha_hex()>, and
I<sha_base64()> functions.

	# Test vector from draft-ietf-ipsec-ciph-sha-256-01.txt

	use Digest::SHA::PurePerl qw(hmac_sha256_hex);
	print hmac_sha256_hex("Hi There", chr(0x0b) x 32), "\n";

=head1 NIST STATEMENT ON SHA-1

I<NIST was recently informed that researchers had discovered a way
to "break" the current Federal Information Processing Standard SHA-1
algorithm, which has been in effect since 1994. The researchers
have not yet published their complete results, so NIST has not
confirmed these findings. However, the researchers are a reputable
research team with expertise in this area.>

I<Due to advances in computing power, NIST already planned to phase
out SHA-1 in favor of the larger and stronger hash functions (SHA-224,
SHA-256, SHA-384 and SHA-512) by 2010. New developments should use
the larger and stronger hash functions.>

ref. L<http://www.csrc.nist.gov/pki/HashWorkshop/NIST%20Statement/Burr_Mar2005.html>

=head1 PADDING OF BASE64 DIGESTS

By convention, CPAN Digest modules do B<not> pad their Base64 output.
Problems can occur when feeding such digests to other software that
expects properly padded Base64 encodings.

For the time being, any necessary padding must be done by the user.
Fortunately, this is a simple operation: if the length of a Base64-encoded
digest isn't a multiple of 4, simply append "=" characters to the end
of the digest until it is:

	while (length($b64_digest) % 4) {
		$b64_digest .= '=';
	}

To illustrate, I<sha256_base64("abc")> is computed to be

	ungWv48Bz+pBQUDeXa4iI7ADYaOWF3qctBD/YfIAFa0

which has a length of 43.  So, the properly padded version is

	ungWv48Bz+pBQUDeXa4iI7ADYaOWF3qctBD/YfIAFa0=

=head1 EXPORT

None by default.

=head1 EXPORTABLE FUNCTIONS

Provided your Perl installation supports 64-bit integers, all of
these functions will be available for use.  Otherwise, you won't
be able to perform the SHA-384 and SHA-512 transforms, both of
which require 64-bit operations.

I<Functional style>

=over 4

=item B<sha1($data, ...)>

=item B<sha224($data, ...)>

=item B<sha256($data, ...)>

=item B<sha384($data, ...)>

=item B<sha512($data, ...)>

Logically joins the arguments into a single string, and returns
its SHA-1/224/256/384/512 digest encoded as a binary string.

=item B<sha1_hex($data, ...)>

=item B<sha224_hex($data, ...)>

=item B<sha256_hex($data, ...)>

=item B<sha384_hex($data, ...)>

=item B<sha512_hex($data, ...)>

Logically joins the arguments into a single string, and returns
its SHA-1/224/256/384/512 digest encoded as a hexadecimal string.

=item B<sha1_base64($data, ...)>

=item B<sha224_base64($data, ...)>

=item B<sha256_base64($data, ...)>

=item B<sha384_base64($data, ...)>

=item B<sha512_base64($data, ...)>

Logically joins the arguments into a single string, and returns
its SHA-1/224/256/384/512 digest encoded as a Base64 string.

It's important to note that the resulting string does B<not> contain
the padding characters typical of Base64 encodings.  This omission is
deliberate, and is done to maintain compatibility with the family of
CPAN Digest modules.  See L</"PADDING OF BASE64 DIGESTS"> for details.

=back

I<OOP style>

=over 4

=item B<new($alg)>

Returns a new Digest::SHA::PurePerl object.  Allowed values for
I<$alg> are 1, 224, 256, 384, or 512.  It's also possible to use
common string representations of the algorithm (e.g. "sha256",
"SHA-384").  If the argument is missing, SHA-1 will be used by
default.

Invoking I<new> as an instance method will not create a new object;
instead, it will simply reset the object to the initial state
associated with I<$alg>.  If the argument is missing, the object
will continue using the same algorithm that was selected at creation.

=item B<reset($alg)>

This method has exactly the same effect as I<new($alg)>.  In fact,
I<reset> is just an alias for I<new>.

=item B<hashsize>

Returns the number of digest bits for this object.  The values are
160, 224, 256, 384, and 512 for SHA-1, SHA-224, SHA-256, SHA-384,
and SHA-512, respectively.

=item B<algorithm>

Returns the digest algorithm for this object.  The values are 1,
224, 256, 384, and 512 for SHA-1, SHA-224, SHA-256, SHA-384, and
SHA-512, respectively.

=item B<clone>

Returns a duplicate copy of the object.

=item B<add($data, ...)>

Logically joins the arguments into a single string, and uses it to
update the current digest state.  In other words, the following
statements have the same effect:

	$sha->add("a"); $sha->add("b"); $sha->add("c");
	$sha->add("a")->add("b")->add("c");
	$sha->add("a", "b", "c");
	$sha->add("abc");

The return value is the updated object itself.

=item B<add_bits($data, $nbits)>

=item B<add_bits($bits)>

Updates the current digest state by appending bits to it.  The
return value is the updated object itself.

The first form causes the most-significant I<$nbits> of I<$data>
to be appended to the stream.  The I<$data> argument is in the
customary binary format used for Perl strings.

The second form takes an ASCII string of "0" and "1" characters as
its argument.  It's equivalent to

	$sha->add_bits(pack("B*", $bits), length($bits));

So, the following two statements do the same thing:

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

=item B<addfile(*FILE)>

Reads from I<FILE> until EOF, and appends that data to the current
state.  The return value is the updated object itself.

=item B<addfile($filename [, $mode])>

Reads the contents of I<$filename>, and appends that data to the current
state.  The return value is the updated object itself.

By default, I<$filename> is simply opened and read; no special modes
or I/O disciplines are used.  To change this, set the optional I<$mode>
argument to one of the following values:

	"b"	read file in binary mode

	"p"	use portable mode

The "p" mode is handy since it ensures that the digest value of
I<$filename> will be the same when computed on different operating
systems.  It accomplishes this by internally translating all newlines in
text files to UNIX format before calculating the digest.  Binary files
are read in raw mode with no translation whatsoever.

For a fuller discussion of newline formats, refer to CPAN module
L<File::LocalizeNewlines>.  Its "universal line separator" regex forms
the basis of I<addfile>'s portable mode processing.

=item B<dump($filename)>

Provides persistent storage of intermediate SHA states by writing
a portable, human-readable representation of the current state to
I<$filename>.  If the argument is missing, or equal to the empty
string, the state information will be written to STDOUT.

=item B<load($filename)>

Returns a Digest::SHA::PurePerl object representing the intermediate
SHA state that was previously dumped to I<$filename>.  If called
as a class method, a new object is created; if called as an instance
method, the object is reset to the state contained in I<$filename>.
If the argument is missing, or equal to the empty string, the state
information will be read from STDIN.

=item B<digest>

Returns the digest encoded as a binary string.

Note that the I<digest> method is a read-once operation. Once it
has been performed, the Digest::SHA::PurePerl object is automatically
reset in preparation for calculating another digest value.  Call
I<$sha-E<gt>clone-E<gt>digest> if it's necessary to preserve the
original digest state.

=item B<hexdigest>

Returns the digest encoded as a hexadecimal string.

Like I<digest>, this method is a read-once operation.  Call
I<$sha-E<gt>clone-E<gt>hexdigest> if it's necessary to preserve
the original digest state.

This method is inherited if L<Digest::base> is installed on your
system.  Otherwise, a functionally equivalent substitute is used.

=item B<b64digest>

Returns the digest encoded as a Base64 string.

Like I<digest>, this method is a read-once operation.  Call
I<$sha-E<gt>clone-E<gt>b64digest> if it's necessary to preserve
the original digest state.

This method is inherited if L<Digest::base> is installed on your
system.  Otherwise, a functionally equivalent substitute is used.

It's important to note that the resulting string does B<not> contain
the padding characters typical of Base64 encodings.  This omission is
deliberate, and is done to maintain compatibility with the family of
CPAN Digest modules.  See L</"PADDING OF BASE64 DIGESTS"> for details.

=back

I<HMAC-SHA-1/224/256/384/512>

=over 4

=item B<hmac_sha1($data, $key)>

=item B<hmac_sha224($data, $key)>

=item B<hmac_sha256($data, $key)>

=item B<hmac_sha384($data, $key)>

=item B<hmac_sha512($data, $key)>

Returns the HMAC-SHA-1/224/256/384/512 digest of I<$data>/I<$key>,
with the result encoded as a binary string.  Multiple I<$data>
arguments are allowed, provided that I<$key> is the last argument
in the list.

=item B<hmac_sha1_hex($data, $key)>

=item B<hmac_sha224_hex($data, $key)>

=item B<hmac_sha256_hex($data, $key)>

=item B<hmac_sha384_hex($data, $key)>

=item B<hmac_sha512_hex($data, $key)>

Returns the HMAC-SHA-1/224/256/384/512 digest of I<$data>/I<$key>,
with the result encoded as a hexadecimal string.  Multiple I<$data>
arguments are allowed, provided that I<$key> is the last argument
in the list.

=item B<hmac_sha1_base64($data, $key)>

=item B<hmac_sha224_base64($data, $key)>

=item B<hmac_sha256_base64($data, $key)>

=item B<hmac_sha384_base64($data, $key)>

=item B<hmac_sha512_base64($data, $key)>

Returns the HMAC-SHA-1/224/256/384/512 digest of I<$data>/I<$key>,
with the result encoded as a Base64 string.  Multiple I<$data>
arguments are allowed, provided that I<$key> is the last argument
in the list.

It's important to note that the resulting string does B<not> contain
the padding characters typical of Base64 encodings.  This omission is
deliberate, and is done to maintain compatibility with the family of
CPAN Digest modules.  See L</"PADDING OF BASE64 DIGESTS"> for details.

=back

=head1 SEE ALSO

L<Digest>, L<Digest::SHA>

The Secure Hash Standard (FIPS PUB 180-2) can be found at:

L<http://csrc.nist.gov/publications/fips/fips180-2/fips180-2withchangenotice.pdf>

The Keyed-Hash Message Authentication Code (HMAC):

L<http://csrc.nist.gov/publications/fips/fips198/fips-198a.pdf>

=head1 AUTHOR

	Mark Shelor	<mshelor@cpan.org>

=head1 ACKNOWLEDGMENTS

The author is particularly grateful to

	Gisle Aas
	Chris Carey
	Alexandr Ciornii
	Jim Doble
	Julius Duque
	Jeffrey Friedl
	Robert Gilmour
	Brian Gladman
        Adam Kennedy
	Andy Lester
	Alex Muntada
	Steve Peters
	Chris Skiscim
	Martin Thurn
	Gunnar Wolf
	Adam Woodbury

for their valuable comments and suggestions.

=head1 COPYRIGHT AND LICENSE

Copyright (C) 2003-2010 Mark Shelor

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

L<perlartistic>

=cut
