The following function calculates the permutations of a given list (typically an array) and lets you group the results by a given number. This is useful when automatically testing login forms bypass, using the strings you can find on this post.
<?php
function permutations($pool, $r = null) {
$n = count($pool);
if ($r == null) $r = $n;
if ($r > $n) return;
$indices = range(0, $n - 1);
$cycles = range($n, $n - $r + 1, -1);
yield array_slice($pool, 0, $r);
if ($n <= 0) return; while (true) { $exit_early = false; for ($i = $r;$i--;$i >= 0) {
$cycles[$i]-= 1;
if ($cycles[$i] == 0) {
if ($i < count($indices)) {
$removed = array_splice($indices, $i, 1);
array_push($indices, $removed[0]);
}
$cycles[$i] = $n - $i;
} else {
$j = $cycles[$i];
$i_val = $indices[$i];
$neg_j_val = $indices[count($indices) - $j];
$indices[$i] = $neg_j_val;
$indices[count($indices) - $j] = $i_val;
$result = [];
$counter = 0;
foreach ($indices as $indx) {
array_push($result, $pool[$indx]);
$counter++;
if ($counter == $r) break;
}
yield $result;
$exit_early = true;
break;
}
}
if (!$exit_early) break;
}
}
$result = iterator_to_array(permutations(array("a","b","c","d","e", 2));
foreach ($result as $row)
print implode(" || ", $row) . PHP_EOL;
echo count($result);
?>
The above code will output the following:
a || b a || c a || d a || e b || a b || c b || d b || e c || a c || b c || d c || e d || a d || b d || c d || e e || a e || b e || c e || d 20