So there’s geocaches which basically involve folks trying to find something hidden, often leaving their name as a discoverer and leaving it for the next person to find.  Don’t worry, it’s real!

On to another invented cipher I came up with: Nullcaches or nullcaching.  Same idea but you hide the ciphertext within a larger block of text which is usually gibberish intended to thwart analysis as well as change letter frequencies.  What’s the trick to retrieval?  A set of predetermined coordinates.  It can be as simple as between all of the L’s or everything after QQ is important.  The recipient then retrieves the message and deciphers it.  This method is useful because it will conceivably be impossible to know what the important ciphertext is and what is gibberish.  A potential weakness is the opposition attempting a series of substitutions or transpositions progressively through the message using smaller and smaller blocks of text until they hopefully retrieve a plaintext message.  But they’d have to know a null cipher was in place and which one.

For K4, I liked the idea and also because of the end of K3: X Can you see anything Q?  or in other words, “Can you see anything between X and Q?”.

Pretty simple coordinates, let’s see what we can pull out.  There are 2 X’s and 4 Q’s in K4.  Two of those Q’s have SJ between them which I will ignore.  There is a forward X to Q relationship towards the beginning of K4 and a reverse X to Q towards the end wrapping back to the middle.  Let’s see the letter strings:

X to Q (beginning)
OGHULBSOLIFBBWFLRV

X to Q (reversed text)
ZKDGWKPFZMTTVPYNBFNIWAIDULKJTAWZZKESS

X to Q (going from Q to X)
SSEKZZWATJKLUDIAWINFBNYPVTTMZFPKWGDKZ 

No string appears to be in plaintext.  Using Decrypto 8.5 by Edwin Olson, we can attempt a substitution solution and see what we get…

X to Q (beginning)
of this voicess being,
out, his voices being
or this voicess beinf

X to Q (reversed text)
HE AFTEMPHCWWZMYO UPONTINAL BED WITH HERS S
HE GATE MY HPWWXMJULY UNTING OVED WITH HERS S
HE LATE BUHPWWKBONJUNCTICLYZED WITH HERS S

X to Q (going from Q to X)

SS GREE ONLY RIBUT NOT ADVAMPHLLKED PROCURE
EED OCCUS PROVING SUGATLAZYWPPXCT YOU KNOC
OO KILLNESHIPMATENT BUYBJDFSSCLUDIN VAIL
 
The first one seems alright but the last two have too much gibberish for my taste.
 
Perhaps a little Googling to see if the first 3 are from a quote:
Yeah, no, not so much.  Could be part of a larger riddle perhaps but by itself, Nullcache has not retrieved the plaintext.
 
Still a nice idea though…