# The Twenty Doors (ROOM 4)

This is part of The Twenty Doors series.
The previous one is The Twenty Doors! (ROOM 3)
The next one is The Twenty Doors! (ROOM 5)

You now enter room 4. This one has a load of A's and B's carved into the wall, along with a message. AAAAA ABAAABAAAB ABBABABBAAAABAA AAAAAABBAAAAABB AAAAB ABAAABAAAB BAABABABAAAABAAABBAABAABABABBA AABABABBABBAABBBAAAA ABAAAABBAA BAABAAABBBAABAA ABABBAAAAAABAAAABBAA AAABABAAAABABBAABBBABAABAABBABAABBABAAAAAAAAAABABB I may not be distinct but I've always loved bacon.

On the floor, as usual, there is a bit of paper.

Bmmp rum gq rfc uyw rm qydcrw!

But this time, there are three doors (not counting the one you just came through). You turn over the paper, and there is something written on the back

This time, press the button on your chosen door to open it, but if you choose the wrong one, prepare to DIE!!!

Hmm... This one involves two cryptograms. Damn. Anyway, you might as well try.

Which door should you go through?

The next door will be added when this door is solved!

• I was assuming that twenty doors meant twenty rooms, but you've used an extra two doors here! I think the next room is just going to have 14 doors in it and will be the end. :) Jul 5, 2015 at 0:34

I just joined StackExchange. This is my shot at the answer:

The door you have to pick is

Door two.

To decrypt the cryptogram on the wall

Use the Baconian cipher with I=J and U=V to decrypt it. That gives you the plain text: 'A IS ONE AND X IS TWENTY FOUR IN THE MAIN CRYPTOGRAM'.

To decrypt the one on the paper

It's encrypted with the affine substitution cipher. Decoding it gives you the plain text: 'Door two is the way to safety!'

On to Room 5 (I hope)!

• Welcome to Stack Exchange, and great answer! :-) Jul 4, 2015 at 10:24
• I don't quite understand where you get those 2 equalities for the Baconian cypher. Jul 4, 2015 at 13:21
• @NateKerkhofs There are two versions of Baconian ciphers - the first one uses the same code for letters I/J and U/V. The second version gives a unique code for each letter. Jul 4, 2015 at 13:27
• The cipher I used is called Affine.
– user9377
Jul 5, 2015 at 8:41
• It looks like an ordinary Caesar +2 cipher to me.
– user88
Jul 24, 2015 at 21:09