# Decrypt this Cryptogram: cs.aoa.daso

The encrypted text is:

(. is a letter separator and <br> or line break is a word separator)

cs.aoa.daso
cs.fsi.rxhg
s.al.dkl.zpt
h.cr.efp.dabh.xfmv.fmsrx
bs.aqr.alpx.kwej
ba.abn.dfvj.fwbdd.fwbdcz.aohlxwz

Some hints;

Hint 0:

Hint: Further Hints use Unscrambling.

Hint 1:

Ehacgn ot sbae teywtn-xis ihelw gtiakn a as neo. pqr=11276.

Hint 2:

Hcum Clascne

Hint 3:

nth Irepm.

Hint 4:

Berawe of Lditpcuaes dcdoe as ocmiposets

Hint 5:

Abck to abes tnywte xsi wiht a as eon

Hint 6:

Do you know about composite numbers

• I haven't downvoted this, but I'm sure that you received those bad feedbacks because this problem lacks of clues. If you encrypt a message with multiple algorithms it's very hard for us to decrypt it without clues. Suppose that we know 15 encryption algorithms. If you encrypt it twice, we have to test 225 solutions, without even knowing that we'll find a good one. Boring, no? – leoll2 May 4 '15 at 12:28
• Now it's better :) – leoll2 May 4 '15 at 12:49
• Clues in some form would be better than outright hints with this one. I can select a random document as a key and do a progressive substitution cipher* starting from the beginning of that doc, and then post the answer here, but it won't actually be solvable unless I give people some hope of finding the document that's the key to start from -- even then they have to figure out what i did. – lorimer May 12 '15 at 11:50
• *(translate alphabet from 1-26. start at 0th word of doc; count up # of words for first letter, replace with beginning letter of that word in doc. continue from prior spot. frex, encrypting TACO with my previous comment as the key would become AADT -- see the problem?) – lorimer May 12 '15 at 11:50
• @lorimer try hint 1, or post problems that you face while decoding. – RE60K May 12 '15 at 12:32

The decrypted message is:

yes you have solved this puzzle

Steps to decrypt are:

1. convert from a-z code to true base-26 (1-9-a-p). In other words, "a" goes to 1, "j" goes to "a", "y" goes to "p", and "z" goes to 10.
2. convert from base-26 to decimal
3. divide each decimal number by the preceeding number, starting over at the beginning of each word.
4. where this division results in a prime number, identify it as the $n^{th}$ prime number. Note that each prime number is only coded once, except for "y".
5. convert from the $n^{th}$ prime number to the letter of the alphabet
6. where the division results in a composite number, the plain text letter has been previously defined. So each repeated letter is assigned a number from the sequence of composite numbers. The assigned composite numbers are shown in the yellow cells below.

• inconsistencies are because you are missing hint 4 – RE60K May 13 '15 at 6:50
• btw can you tell which function you used in excel? – RE60K May 13 '15 at 6:51
• we need to chat. getting a chatroom. – RE60K May 13 '15 at 7:00
• come here chat.stackexchange.com/rooms/23724/… – RE60K May 13 '15 at 7:01
• not quite the correct composite thing, there's a definite logic to it. you're close. good job! – RE60K May 17 '15 at 11:06