A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
Right now, we have:
YR RUST TU USYYTS UOT UPUT
-+ ++++ -+ -++--- +-+ ++--
and the clues
"encryption=HALFHABET"
"method=INCREMENT_>13"
"method2=WHEN_NOT_INCREMENT_THEN_--"
If it's greater than 13, increment; otherwise, decrement. We don't have letters in the first half of the alphabet; that's probably why it's called halfhabet.
The "+" or "-" probably denotes whether the letter was reached by an increment or decrement. The increment for - or + are probably the same value. Now since M is the highest value that can be decremented, then that means that the maximum increment value is 25, any higher and it would wrap around into the first half of the alphabet. Now the Z is the highest value that can be incremented which means that the lowest possible increment value is probably 14-15 (it depends on what FFS considers to be the dividing point between first or second half of the alphabet)
Now let's look at the first word of the code
YR
-+If my logic is correct, then it would mean Y stands for either M or lower and R stands for either N or higher.
Now let's assume the first word is A in order to form AT, AL, or AP. Then A would decrement by 2 in order to wrap around and reach Y (1, 26, 25,). Of course we already established that the increment/decrement value cannot be lower than 14-15 (hopefully I can choose one of these numbers), therefore the first word is not at.
Now let's try the word IN. I would have to decrement by 10 in order to reach Y. Meaning that It doesn't begin with I
Now let's try MY. M would have to decrement by 14 to reach Y. This satisfies the first criteria. Now if we decremented R by 14 we get D which gives us the word MD. Now this may stand for MayDay or it means that M is wrong. Of course when you continue this pattern you just get gibberish and since M is the only value that can be decremented to reach Y without being lower than 14, therefore there is something wrong with my methodology. Maybe remove the 14-15 rule and Z is simply not used in the encrypted message for decrements. You write Z with increments.
With this new rule in place let's try.......Drumroll......HI!
H would have to decrement by 9 in order to reach Y, coincidentally when R is decremented by 9 you get I.
Now lets continue with the next word in the sentence RUST(all +)
R=I
U=L
S=J
T=K
Damm... Giberish
maybe next word?
T=C
U=D
Not Giberish... but suspicious
U=D
S=J
Y=P
Y=H
T=C
S=B
More Giberish
Okay, I think that's enough. I'm probably wrong. It might be a possibility that the increment value is random for each word though.
I'm keeping this post here merely so noone has to waste their time coming up with the same idea as me.