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MD5 algo with padding commented out this makes it suitable for use in length extension attacks as output can then be used as initial values for next block
<?php
//Pre-processing: adding a single 1 bit
// append "1" bit to message
// Notice: the input bytes are considered as bits strings,
// where the first bit is the most significant bit of the byte.[46]
//Pre-processing: padding with zeros
// append "0" bit until message length in bits ≡ 448 (mod 512)
function preProcess($message) {
// $message .= chr(128);
// while (((strlen($message) + 8) % 64) !== 0) {
// $message .= chr(0);
// }
return $message;
}
function getShiftsAndConstants() {
//s specifies the per-round shift amounts
$s = [ 7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22,
5, 9, 14, 20, 5, 9, 14, 20, 5, 9, 14, 20, 5, 9, 14, 20,
4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23,
6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21];
$K = [];
for ($i =0; $i < 64; $i++) {
$K[$i] = floor(abs(sin($i + 1)) * (pow(2, 32))) & 0xffffffff;
}
return [$s, $K];
}
//Process the message in successive 512-bit chunks:
function md5_hash($message) {
//Initialize variables:
list($a, $b, $c, $d) = [0x67452301, 0xefcdab89, 0x98badcfe, 0x10325476];
list($s, $K) = getShiftsAndConstants();
// append original length in bits mod (2 pow 64) to message
$originalSize = strlen($message) * 8;
$message = preProcess($message);
// break chunk into sixteen 32-bit words M[j], 0 ≤ j ≤ 15
$chunks = str_split($message, 64);
foreach ($chunks as $chunk) {
list($aa, $bb, $cc, $dd) = [$a, $b, $c, $d];
$words = str_split($chunk, 4);
foreach ($words as $i => $chrs) {
$chrs = str_split($chrs);
$word = '';
//little endian
$chrs = array_reverse($chrs);
foreach ($chrs as $chr) {
$word .= sprintf('%08b', ord($chr));
}
$words[$i] = bindec($word);
}
if (count($words) < 16) {
// $words[] = 0x00000000ffffffff & $originalSize;
// $words[] = 0xffffffff00000000 & $originalSize;
}
//Main loop:
for ($i = 0; $i < 64; $i++) {
$step = floor($i /16);
switch ($step) {
case 0;
$f = ($b & $c) | (~$b & $d);
$g = $i;
break;
case 1;
$f = ($d & $b) | (~$d & $c);
$g = (5 * $i + 1) % 16;
break;
case 2;
$f = $b ^ $c ^ $d;
$g = (3 * $i + 5) % 16;
break;
case 3;
$f = $c ^ ($b | ~$d);
$g = (7 * $i) % 16;
break;
}
$temp = $d;
$d = $c;
$c = $b;
$b = $b + rotl(($a + $f + $K[$i] + $words[$g]) & 0xffffffff, $s[$i]) ;
$a = $temp;
}
//Add this chunk's hash to result so far:
$a = $a + $aa & 0xffffffff;
$b = $b + $bb & 0xffffffff;
$c = $c + $cc & 0xffffffff;
$d = $d + $dd & 0xffffffff;
}
$x = pack('V4', $a, $b, $c, $d);
return bin2hex($x);
}
//leftrotate function definition
function rotl ($x, $c)
{
return ($x << $c) | ($x >> (32 - $c));
}
echo md5_hash(file_get_contents(__DIR__.'/../fastcoll/proto.php'));
@elMianda
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elMianda commented Apr 20, 2022

hola

@natmchugh
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natmchugh commented Apr 21, 2022

hola

Hola, qué pasa. ¿Tienes una pregunta?

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