⇥ Challenge 2.0 goes unresolved!

It looks like I might have aimed a little too high for my second challenge—which has gone unanswered.


The result was actually relatively simple to resolve. The encrypted cypher contained a long word—SGDWPALBKCTXH—which was the key to the entire thing. The only word of 13 characters in that blog post was “sophisticated,” which, given the starting point should have given would-be solvers a starting clue.

In reality, the encryption mechanism was a simple addition cypher in which the zero-based alphabetical position of each letter (i.e.: A=0, B=1, etc.) was replaced with the sum of itself plus the preceding letter (excluding spaces).

The solution could therefore be obtained by reversing the process—for example with a simple algorithm like this:


$code = “SGDWPALBKCTXH LVQHIH LA LAPA JZLGOP”;
echo $code[0];

$offset = ord(‘A’);
$prev = ord($code[0]) – $offset;

for ($i = 1; $i < strlen($code); $i++) {
if (‘ ‘ === $code[$i] ) {
echo ‘ ‘;
continue;
}
$letter = ord($code[$i]) – $offset – $prev;
if ($letter < 0) {
$letter = $letter + 26;
}
$prev = $letter;
echo chr($letter + $offset);
}

This gives the final solution: “SOPHISTICATED INDEED IS THIS RIDDLE”.