## GCHQ Christmas Puzzle Solutions Part 1

I've just made some progress with the competition so I thought I'd bring people up to date with where I am so far.

The Sudoku was solvable and the fact that I was looking for the word penguin sped up the process. The waddling trail left by the penguin spelt out: seemessageinpengiuns

Around the outside of the double page were a whole lot of penguins some of which were wearing helmets. The helmeted ones were in about the right distribution to be spaces so I was looking at some sort of cipher. At first I tried to make semaphore fit, but the penguins weren't very good at lifting their arms above their heads; and trying to make their beak direction count as one of the flags led to nonsense.

However the one letter word had to be either a or i and I took some guesses such as the repeated three letter word being the. Eventually the whole thing fell out as a painstaking substitution cipher which spells:

The pages inside the covers of a book are referred to as endpapers even the ones at the front.

Inside the front and back covers we have grids of letters in weird orientations.

I'd got to this point on Christmas day, but at that point I hit a bit of a wall. Neither endpaper was coming out and while I had most of the celebrities, I couldn't see what to do with them. The first names of the celebrities began in turn with A, then B then C etc.

However, during the course of a mock exam I have managed to decipher the first endpaper. Reading from left to right doesn't put the spaces in sensible places, but reading top to bottom does. After forcing some of the three letter words to be the I've worked out that it is a combination of 8 caeser shifts. For letters in the normal upright orientation there is no shift. For letters 45 degrees clockwise there is a shift of 1 backwards. For letters 90 degrees clockwise there is a shift of 2 backwards and so on.

Putting this together (using excel) I have the message:

To enter competition go to the web page www dot gchqpuzzlebook dot co dot uk slash egatstxeneht and enter the appropriate password stop this will allow you to access some additional puzzles stop the password must first be encoded using a simple sadsymyaympw cipher stop best wishes gchq stop

www.gchqpuzzlebook.co.uk/egatstxeneht does indeed get you to a password protected page. I'm assuming that sadsymyaympw is substitution in the given substitution cipher which gives various clues such as s->s and u->a. This matches up with Susan Sarandon and Ursula Andress. Looking back at the celebraties I can see that none of the surnames have the same first letter. This means that if I get all the names then I will know the cipher and the more I get, the more it cuts down possible surnames for the others. This is my main focus at the moment.

Update! I've solved the Back Endcover. I was looking to make most of the 3 letter words the and most of the 4 letter words stop. It turns out it was semaphore being rotated. If you hold of the semaphore flags for A then rotate you get H then O then T then nothing then W then Z and finally then G.

Similarly the other letters fall into groups. So our permutations are: [A,H,O,T,gap,W,Z,G], [C,K,Q,Y,V,E,M,S], [B,I,P,U,J,X,F,N] and [D,L,R,gap].

Decoding it we get:

In order to construct the required twenty four character password you must concatenate together three eight letter words stop the first word is the solution to the meta puzzle stop the second word is taken from the sudoku message stop the third word is taken from the penguin message stop

So now I know where to get the password. The meta puzzle is quite a large undertaking (and I thought it was unrelated to the main competition; I've been doing it alongside) so it will have its own thread. The two 8 letter words must be penguins and referred respectively so possibly it makes a sensible phrase.

Ok, solved. The celebrity first names all start with the letters of the alphabet in order. Their surnames are all distinct letters of the alphabet as well which gives us a mapping. AJ, BD, CE, DK, EZ, FR, GI, HL, IM, JO, KH, LV, MX, NW, OP, PU, QT, RG, SS, TY, UA, VC, WN, XB, YF and presumably ZQ as the left over letters.

This fits with the substitution from the front endpaper and it gives us our translation for the password.

I've now solved the meta puzzle (although 2 of the 8 picture bits are still unsolved) which gives the answer OCTAGRAM.

Therefore the passphrase is OCTAGRAMPENGUINSREFERRED, which becomes peyjigjxuzwiamwsgzrzggzk. This is the correct password.