No thanks.

Sounds interesting, but also time consuming.

Would we be allowed to use computers to crack these?

aoe3, I was thinking only handmade encoding and decoding, to keep it fair, but if you can find 7 people do go no-holds-barred, I'm down.

Actually, I was just curious - I don't want to use computers; that would just defeat the point.

Anyway, I don't think this would be too practical. Having your orders publicised would make the game very... well... odd.

I find it interesting. But... encoding with a simple calculador and a little free time can result in quite a bit of "hardness". And decrypting can be easy or hard. But I think it is fun. We could make a private 5 buy in game, when you have cash count me in! And what about public key by hand, too? Allowed there?

Also, I think it should be clear what type of encoding is allowed. For instance, you can have a key where A is space, Smy is Con, Con is Bul and M is also M. Thus you write as a "encoded order" Smy M Con which has a clear sense... but the real order is A Con M Bul.

I mean, it should be a "plain cipher". Something you do to each letter (or maybe groups of letters). Don't know how to define it exactly. You know what I mean?

Yeah, there should be a simple set of rules defining what's allowed and what isn't. How about no deliberately misleading results (i.e., what you just described), no double-keying (for example, it would be possible to write a set of orders that could be decrypted with two different keys to reveal two different sets of instructions), only symmetric keys (you encrypt it with the same key you decrypt it with). Can you think of anything else that should be necessary, other than a ban on any computational aid more powerful than a non-scientific calculator?

Not really. But I think that non-symmetric keys (allowing public key schemes, which done by a NSCalc should be quite easy to break, even by hand) should be allowed, as they would add some diplomatic system (thus, not "no-press"). And double-keying... SHOULD be allowed. It's where the fun is!!

one key per turn?
If I can choose this key after deciding upon my orders then its very easy.
e.g: Say I was Italy
I might encode:
"A Ven Hold" <-> 1016
"A Rome move to APU" <-> 3453
"F Nap move to Ion" <-> 13

or I just encode all my orders as X, try breaking that!

The point is, I'm the only one who has to be able to decode my orders and since I can choose my key after choosing my orders I just build my orders into my key.

Alternative suggestion: how about, only people with neighbouring units can exchange private messages, all other messages have to be public.
So neighbouring units exchange keys and can then communicate "privately" in the public channel with encrypted messages.

Heh, all right - double-keying would certainly make things more interesting.

Sceptic, keep in mind you have to prove decodability afterwards. Also, since we're only allowing character substitution ciphers (I believe) that wouldn't work.

You make a good point, though, that would be a cool addition. How about to make it even more interesting, you can only communicate with someone when one of your units is occupying one of their centers? Of course, this means only in springtime, but...

So just character substitution ciphers?
Can the substitutions be position dependent, like the Nazi Enigma?
Are transpositions allowed? i.e encode abcdefg to fcbgae.
What about single character to multiple character substitutions? e.g a to 100101
How do the orders have to be formated?
would synonyms be allowed?
A Vinice attack Trieste
F Ion sail to Tunis
A Rome advance on Apu
A Mar stay put

I've always been a fan of the "Shifting E" style of cipher. Simply put, the first letter given is the Key, corresponding to the letter "E". The next letter in order from the Key would be F, then the next G, and so forth. The catch is that every time you reach a new "E", an additional letter is given. That letter is a new Key, which superseeds the old one for every letter after that.

So, "F London supports move F North Sea to English Channel" would be "F G Mpoepo tvqqpsut npwfd E Mnqsg Rdea to Efohmjti Dibooeel"

Yeah, there's a lot of wiggle room here, and those of us who have more than a passing interest in ciphers are going to be at a massive advantage.

For example, try cracking this:

JDD BB ZQH WWE ZZT JBNH

It's a Vigenere Cipher. The passcode is 'Spring' in this case, and the result is:

ROM TO TYS FOR THE STAB.

As long as I choose a sufficiently random passcode, most people aren't going to have a lot of luck cracking it....

to much work for me, I'll stick to gunboats xD

If there are enough people interested in ciphers, count me in, of course. Also, I'd prefer a quite long span (48++ hours) so there is time to think, encode, read, decode everyone and so on.

I don't recommend this. I was in a UN Varient that we ended up drawing because everyone was really upset. Basically the honour system has holes in it, like if someone missed the one day deadline do they have to NMR? Also, plausible codes or non-plausible? This might sound fun in your head but it will lead only to frustration.

I think this got cold. I've been thinking... maybe hand encoded but allowing for computer assisted breaking?

I like converting from base N to base sqrt(N), where N is the highest letter available in the message. I and some friends used to do this to pass notes in high school. To make the note quickly decipherable, the first character was the top most character in the new base.

For instance:

F LON - ENG

This is base 25 (O is the 15th letter of the English alphabet). The new base is 5 (if it isn't exact, round to the nearest integer, A-C=3, D-K=4, L-U=5, V-Z=6). Assuming all messages have characters, this is a pretty tricky encoding that can be very difficult to break as there are a number of original bases for each reduced base, but easy to decode if you know the original base. We would usually include a word that was the base. As most phrases have letters above A and I, a single character word would usually give you the key. Now, do each word as a number.

30 401140 - 233413

And tack on the cipher (in this case 43).

30 4011410 43 233413

In this example I chose to replace the innocuous hyphen with the number. Deciphering is as simple as knowing that the range of the base is from 0 to 6 and seeing the 4 means it could only be base 5 or base 6, so try the two short words in base 5 and base 6 and see if you get a single letter than corresponds to that base as it's square root. It is possible you may have to run it a couple of times, but highly unlikely. Either way, a simple calculator could be used to decipher the message.