This is the fourth segment of ciphertext from the Copperplate.

We’ll call it V1 for now (V1 has 97 letters)

OBKR
UOXOGHULBSOLIFBBWFLRVQQPRNGKSSO
TWTQSJQSSEKZZWATJKLUDIAWINFBNYP
VTTMZFPKWGDKZXTJCDIGKUHUAUEKCAR

Given the possibility (probability) that we need to adjust it somehow, I’m going to list a sort of ongoing list of possible variations of K4 that may aid solution.

As mentioned several times before, I find it significant that you can find the keyword KRYPTOS on the ends of K4. V2 will then be the regular K4 with these letters removed.

V2 (90 letters)

OB
UOXOGHULBSOLIFBBWFLRVQQPRNGKS
WTQSJQSSEKZZWATJKLUDIAWINFBN
VTTMZFPKWGDKZXTJCDIGKUHUAUEKCAR

I considered the possibility that the location of the letters suggests a transposition, i.e. line up the keyword to line up the ciphertext.

V3 (97 letters)

Take the original

OBKR
UOXOGHULBSOLIFBBWFLRVQQPRNGKSSO
TWTQSJQSSEKZZWATJKLUDIAWINFBNYP
VTTMZFPKWGDKZXTJCDIGKUHUAUEKCAR

reverse row 2

OBKR
OSSKGNRPQQVRLFWBBFILOSBLUHGOXOU
TWTQSJQSSEKZZWATJKLUDIAWINFBNYP
VTTMZFPKWGDKZXTJCDIGKUHUAUEKCAR

shift two letters to the right on lines 1 and 3

KROB
OSSKGNRPQQVRLFWBBFILOSBLUHGOXOU
YPTWTQSJQSSEKZZWATJKLUDIAWINFBN
VTTMZFPKWGDKZXTJCDIGKUHUAUEKCAR

switch lines 2 & 3

KROB
YPTWTQSJQSSEKZZWATJKLUDIAWINFBN
OSSKGNRPQQVRLFWBBFILOSBLUHGOXOU
VTTMZFPKWGDKZXTJCDIGKUHUAUEKCAR

still possible to remove the KRYPTOS

V4 (90 letters)

OB
WTQSJQSSEKZZWATJKLUDIAWINFBN
SKGNRPQQVRLFWBBFILOSBLUHGOXOU
VTTMZFPKWGDKZXTJCDIGKUHUAUEKCAR

Returning to V3 and considering digraphs (yeah, I’m having a hard time letting it go), you can line up the letters in digraph columns

V5 (90 used letters, KRYPTOS forms the column headers)

KR YPT OS (NULL)
OB TW SK VT
TQ GN TM
SJ RP ZF
QS QQ PK
SE VR WG
KZ LF DK
ZW WB ZX
AT BF TJ
JK IL CD
LU OS IG
DI BL KU
AW UH HU
IN GO AU
FB XO EK
N U CA
R

I’ll work on getting this into an Excel table tomorrow

V6 (90 used letters, KRYPTOS forms the column headers)

Why have YPT unless maybe it’s in triplets?

KR YPT OS (NULL)
OB TWT SK VT
QSJ GN TM
QSS RP ZF
EKZ QQ PK
ZWA VR WG
TJK LF DK
LUD WB ZX
IAW BF TJ
INF IL CD
B N OS IG
BL KU
UH HU
GO AU
XO EK

U CA
R

No arrangement of K4 suggests an answer just by rearranging the letters. While it may prove a little time-consuming, I think I may attempt the more promising cipher systems I find across all 6 arrangements in order to be sure that the answer is not missed inadvertently. I’m wondering if the columnar arrangements are meant to be read off horizontally to create a new letter/digraph string but don’t know at this stage.

I’ve been meaning to do this but haven’t found the time until now…
It’s always struck me as odd that you can find every single letter of the alphabet in K4.  So I removed an alphabets worth of letters and generated the slimmer version of K4.  I started with A and just went in order, removing the next B after that and then looking for the next C and so on.

V7

OBKR
UOXOGHULBSOLBBWFLRVQPKS
WTQSQSSEZZWTJKDIAWINFN
TTFPKGDKZTJIGKUUAUKCAR

-Kryptos Fan