secretcodessedocterces
s x e x c x r x e x t x c x o x d x e x s
I'm not an expert in secret codes. In fact, you might know more about them than I do. However, in case you are looking for some ideas, here are a few suggestions for you to play around with. These are all codes based on the alphabet.
The easiest code you can make is simply by reversing the alphabet like this:
Using this, SECRET CODE becomes HVXIVG XLWV. It's fairly obvious that there are two words in that message, so you could write it in a different way, for example HVXIVGXLWV or HVXIV GXLWV.
In this one, you split the alphabet into two parts. Place the second half below the first half. Then you simply take the letter which pairs with the original letter. SECRET CODE becomes FRPERG PBQR or FRPERGPBQR. You could break it up into different groups, such as FRP ERG PBQ R.
A code-breaker might crack that one easily, so let's look at...
In this one, the last letter of the alphabet in the lower row has been moved to the front. All the other letters move one to the right. Now SECRET CODE becomes RDBQDS BNCD.
Aha, but you could use the lower line for your original word, and codify if with the upper line. If you do that, SECRET CODE becomes TFDSFU DPEF.
How will the receiver know which version you've used? One way of telling them is to put a key-letter at the beginning. The first letter of each line, A or Z, might be too obvious. You could use the last letter of the line, Z or Y. It could become the first letter or the last letter of your message. But you can make it even more cryptic with...
The lower row has been shift by two letters, so that it starts with the last two letters of the alphabet. I'll let you work out what SECRET CODE would be, reading from top to bottom and from bottom to top. But how will you tell the receiver which version you are using, this time?
One way would be to start with the second pair of letters, BZ, but that gives away the clue that Z is a key to the code. The last two letters, ZX, also provide a clue. So perhaps you could use the pair that comes after the 2-letter shift, CA.
This is where you start using your brain to think up ways of telling the receiver (a) which code is being used, and (b) which way round it is being used.
Here are some more charts. They might give you hints and ideas of other ways of using the 2-letter shift and telling the receiver how you have used it.
If the idea appeals to you, you could try going further than a 2-letter shift, and see what happens. You could also try the same idea with the Half Alphabet system, in the second chart above.
There's another page, called Going round in circles