RESSOURCES 
 
Une implémentation en Perl de l'algorithme MD5
Sous licence GPL 17 septembre 2001
 
 


Sur le modèle du Javascript déjà fourni dans nos colonnes, ce programme Perl renvoie le résultat du hachage MD5 d'une chaîne.

# Derived from the RSA Data Security, Inc. MD5 Message-Digest Algorithm

use strict;
package md5;
require Exporter;
@md5::ISA = qw(Exporter);
@md5::EXPORT = qw(md5 md5_init md5_update md5_final);

# MD5 context
my @state;      # array of four integers (A, B, C, D)
my @count;      # number of bits, modulo 2^64, lsb first
my $buffer;     # accumulates bytes until we get a 64-byte block to process

my $PADDING = "\200\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0" .
                "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0" .
                "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0" .
                "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0";


# Given '$str', returns digest of '$str'
sub md5 # ($str)
{
        my ($str) = @_;

        my $digest;

        md5_init();
        md5_update($str);
        $digest = md5_final();
        return $digest;
}


# Finishes the MD5 calculation and returns the digest
sub md5_final
{
        my $bits;
        my $index;
        my $pad_len;

        # Save number of bits
        $bits = md5_encode(@count);

        # Pad out to 56 mod 64.
        $index = ($count[0] >> 3) & 0x3f;
        if ($index < 56)
          {
          $pad_len = 56 - $index;
          }
        else
          {
          $pad_len = 120 - $index;
          }
        md5_update(substr($PADDING,0,$pad_len));

        # Append length (before padding)
        md5_update($bits);

        return md5_encode(@state);
}


# Initialize MD5 context to start a new digest
sub md5_init
{
        @count = (0,0);
        # magic initialization constants
        @state = (0x67452301, 0xefcdab89, 0x98badcfe, 0x10325476);
        $buffer = '';
}


# Process another block of message, updating context
sub md5_update # ($input)
{
        my($input) = @_;

        my $i;
        my $index;
        my $input_len;
        my $part_len;

        $input_len = length($input);

        # Compute number of bytes mod 64
        $index = (($count[0] >> 3) & 0x3F);

        # Update number of bits
        $count[0] = $count[0] + ($input_len << 3);
        if ($count[0] != ($count[0] & 0xffffffff))      # overflow
          {
          $count[0] = 0;
          $count[1] = $count[1] + 1;
          }
        $count[1] = $count[1] + ($input_len >> 29);

        $part_len = 64 - $index;

        # Transform as many times as possible.

        if ($input_len < $part_len)
          {
          $i = 0;
          }
        else
          {
          substr($buffer,$index,$part_len) = substr($input,0,$part_len);
          md5_transform($buffer);

          for ($i = $part_len; $i + 63 < $input_len; $i += 64)
            {
            md5_transform(substr($input,$i,64));
            }
          $index = 0;
          }

        # Buffer remaining input
        substr($buffer,$index,($input_len - $i)) =
                                          substr($input,$i,($input_len - $i));
}


sub add_unsigned # ($a1,...,$an)
{
        my $addend;
        my $sum;

        $sum = 0;
        foreach $addend (@_)
          {
          $sum = (($sum & 0x7fffffff) + ($addend & 0x7fffffff)) ^
                  ($sum & 0x80000000) ^ ($addend & 0x80000000);
          }

        return $sum;
}


sub FF # ($a,$b,$c,$d,$x,$s,$ac)
{
        my($a,$b,$c,$d,$x,$s,$ac) = @_;

        $a = add_unsigned($a,(($b & $c) | (~$b & $d)),$x,$ac);
        $a = rotate_left($a,$s);
        return add_unsigned($a,$b);
}


sub GG # ($a,$b,$c,$d,$x,$s,$ac)
{
        my($a,$b,$c,$d,$x,$s,$ac) = @_;

        $a = add_unsigned($a,(($b & $d) | ($c & ~$d)),$x,$ac);
        $a = rotate_left($a,$s);
        return add_unsigned($a,$b);
}


sub HH # ($a,$b,$c,$d,$x,$s,$ac)
{
        my($a,$b,$c,$d,$x,$s,$ac) = @_;

        $a = add_unsigned($a,($b ^ $c ^ $d),$x,$ac);
        $a = rotate_left($a,$s);
        return add_unsigned($a,$b);
}


sub II # ($a,$b,$c,$d,$x,$s,$ac)
{
        my($a,$b,$c,$d,$x,$s,$ac) = @_;

        $a = add_unsigned($a,($c ^ ($b | ~$d)),$x,$ac);
        $a = rotate_left($a,$s);
        return add_unsigned($a,$b);
}


# Returns packed version of $input in array of integers
# length of $input must be a multiple of 4
sub md5_decode # ($input)
{
        my($input) = @_;

        my $i;
        my $j;
        my $len;
        my @output;

        $len = length($input);
        $i = 0;
        $j = 0;
        while ($j < $len)
          {
          $output[$i] = ord(substr($input,$j,1)) |
                      (ord(substr($input,$j+1,1)) <<  8) |
                      (ord(substr($input,$j+2,1)) << 16) |
                      (ord(substr($input,$j+3,1)) << 24);
          $i = $i + 1;
          $j = $j + 4;
          }

        return @output;
}


# Returns character version of (array of integers) @input
sub md5_encode # (@input)
{
        my(@input) = @_;

        my $output;
        my $i;
        my $len;

        $len = $#input + 1;
        $i = 0;
        $output = '';
        while ($i < $len)
          {
          $output = $output . chr( $input[$i]        & 0xff);
          $output = $output . chr(($input[$i] >>  8) & 0xff);
          $output = $output . chr(($input[$i] >> 16) & 0xff);
          $output = $output . chr(($input[$i] >> 24) & 0xff);
          $i = $i + 1;
          }

        return $output;
}


# MD5 basic transformation. Transforms state based on $block.
# $block must contain exactly 64 bytes.
sub md5_transform # ($block)
{
        my($block) = @_;

        my $a = $state[0];
        my $b = $state[1];
        my $c = $state[2];
        my $d = $state[3];
        my @x;

        @x = md5_decode($block);

# Round 1
        $a = FF($a,$b,$c,$d,$x[ 0], 7,0xd76aa478); # 1
        $d = FF($d,$a,$b,$c,$x[ 1],12,0xe8c7b756); # 2
        $c = FF($c,$d,$a,$b,$x[ 2],17,0x242070db); # 3
        $b = FF($b,$c,$d,$a,$x[ 3],22,0xc1bdceee); # 4
        $a = FF($a,$b,$c,$d,$x[ 4], 7,0xf57c0faf); # 5
        $d = FF($d,$a,$b,$c,$x[ 5],12,0x4787c62a); # 6
        $c = FF($c,$d,$a,$b,$x[ 6],17,0xa8304613); # 7
        $b = FF($b,$c,$d,$a,$x[ 7],22,0xfd469501); # 8
        $a = FF($a,$b,$c,$d,$x[ 8], 7,0x698098d8); # 9
        $d = FF($d,$a,$b,$c,$x[ 9],12,0x8b44f7af); # 10
        $c = FF($c,$d,$a,$b,$x[10],17,0xffff5bb1); # 11
        $b = FF($b,$c,$d,$a,$x[11],22,0x895cd7be); # 12
        $a = FF($a,$b,$c,$d,$x[12], 7,0x6b901122); # 13
        $d = FF($d,$a,$b,$c,$x[13],12,0xfd987193); # 14
        $c = FF($c,$d,$a,$b,$x[14],17,0xa679438e); # 15
        $b = FF($b,$c,$d,$a,$x[15],22,0x49b40821); # 16

# Round 2
        $a = GG($a,$b,$c,$d,$x[ 1], 5,0xf61e2562); # 17
        $d = GG($d,$a,$b,$c,$x[ 6], 9,0xc040b340); # 18
        $c = GG($c,$d,$a,$b,$x[11],14,0x265e5a51); # 19
        $b = GG($b,$c,$d,$a,$x[ 0],20,0xe9b6c7aa); # 20
        $a = GG($a,$b,$c,$d,$x[ 5], 5,0xd62f105d); # 21
        $d = GG($d,$a,$b,$c,$x[10], 9, 0x2441453); # 22
        $c = GG($c,$d,$a,$b,$x[15],14,0xd8a1e681); # 23
        $b = GG($b,$c,$d,$a,$x[ 4],20,0xe7d3fbc8); # 24
        $a = GG($a,$b,$c,$d,$x[ 9], 5,0x21e1cde6); # 25
        $d = GG($d,$a,$b,$c,$x[14], 9,0xc33707d6); # 26
        $c = GG($c,$d,$a,$b,$x[ 3],14,0xf4d50d87); # 27
        $b = GG($b,$c,$d,$a,$x[ 8],20,0x455a14ed); # 28
        $a = GG($a,$b,$c,$d,$x[13], 5,0xa9e3e905); # 29
        $d = GG($d,$a,$b,$c,$x[ 2], 9,0xfcefa3f8); # 30
        $c = GG($c,$d,$a,$b,$x[ 7],14,0x676f02d9); # 31
        $b = GG($b,$c,$d,$a,$x[12],20,0x8d2a4c8a); # 32

# Round 3
        $a = HH($a,$b,$c,$d,$x[ 5], 4,0xfffa3942); # 33
        $d = HH($d,$a,$b,$c,$x[ 8],11,0x8771f681); # 34
        $c = HH($c,$d,$a,$b,$x[11],16,0x6d9d6122); # 35
        $b = HH($b,$c,$d,$a,$x[14],23,0xfde5380c); # 36
        $a = HH($a,$b,$c,$d,$x[ 1], 4,0xa4beea44); # 37
        $d = HH($d,$a,$b,$c,$x[ 4],11,0x4bdecfa9); # 38
        $c = HH($c,$d,$a,$b,$x[ 7],16,0xf6bb4b60); # 39
        $b = HH($b,$c,$d,$a,$x[10],23,0xbebfbc70); # 40
        $a = HH($a,$b,$c,$d,$x[13], 4,0x289b7ec6); # 41
        $d = HH($d,$a,$b,$c,$x[ 0],11,0xeaa127fa); # 42
        $c = HH($c,$d,$a,$b,$x[ 3],16,0xd4ef3085); # 43
        $b = HH($b,$c,$d,$a,$x[ 6],23, 0x4881d05); # 44
        $a = HH($a,$b,$c,$d,$x[ 9], 4,0xd9d4d039); # 45
        $d = HH($d,$a,$b,$c,$x[12],11,0xe6db99e5); # 46
        $c = HH($c,$d,$a,$b,$x[15],16,0x1fa27cf8); # 47
        $b = HH($b,$c,$d,$a,$x[ 2],23,0xc4ac5665); # 48
# Round 4
        $a = II($a,$b,$c,$d,$x[ 0], 6,0xf4292244); # 49
        $d = II($d,$a,$b,$c,$x[ 7],10,0x432aff97); # 50
        $c = II($c,$d,$a,$b,$x[14],15,0xab9423a7); # 51
        $b = II($b,$c,$d,$a,$x[ 5],21,0xfc93a039); # 52
        $a = II($a,$b,$c,$d,$x[12], 6,0x655b59c3); # 53
        $d = II($d,$a,$b,$c,$x[ 3],10,0x8f0ccc92); # 54
        $c = II($c,$d,$a,$b,$x[10],15,0xffeff47d); # 55
        $b = II($b,$c,$d,$a,$x[ 1],21,0x85845dd1); # 56
        $a = II($a,$b,$c,$d,$x[ 8], 6,0x6fa87e4f); # 57
        $d = II($d,$a,$b,$c,$x[15],10,0xfe2ce6e0); # 58
        $c = II($c,$d,$a,$b,$x[ 6],15,0xa3014314); # 59
        $b = II($b,$c,$d,$a,$x[13],21,0x4e0811a1); # 60
        $a = II($a,$b,$c,$d,$x[ 4], 6,0xf7537e82); # 61
        $d = II($d,$a,$b,$c,$x[11],10,0xbd3af235); # 62
        $c = II($c,$d,$a,$b,$x[ 2],15,0x2ad7d2bb); # 63
        $b = II($b,$c,$d,$a,$x[ 9],21,0xeb86d391); # 64

        $state[0] = add_unsigned($state[0],$a);
        $state[1] = add_unsigned($state[1],$b);
        $state[2] = add_unsigned($state[2],$c);
        $state[3] = add_unsigned($state[3],$d);
}


# rotate $x left $n bits.
sub rotate_left # ($x,$n)
{
        my($x,$n) = @_;

        return(($x << $n) | ($x >> (32 - $n)) & 0xffffffff);
}

1;      # for require
 
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