Playfair cipher: ran wordlist against all the following possibilities: the text as is handling double letters (bad practice!); removing one of each prohibited double; removing both of each prohibited double; removing the J's first then one or both of each double.

Building the Playfair square row-wise, spiral or boustrophedon; and with the alphabetical fill-in starting from A, from the last key letter used, or the last key letter even if suppressed as a duplicate.

 K R Y P T . K R Y P T . K R Y P T
 O S A B C . I L M N O . C B A S O
 D E F G H . H X Z Q S . D E F G H
 I L M N Q . G W V U A . Q N M L I
 U V W X Z . F E D C B . U V W X Z

 S A N B O . S A N B O . S A N B O
 R C D E F . R T U V W . R P Q T U
 G H I K L . X Y Z C D . V W X Y Z
 M P Q T U . E F G H I . C D E F G
 V W X Y Z . K L M P Q . H I K L M

No interesting results.

Message 30 3 possible playfair cipher tables. (Elonka)

Message 42 Argument against playfair based on letter frequencies. (Gary Warzin)

Message 47 Playfair doesn't necessarily make even frequency distribution, with example. Link to playfair solver (Elonka)

Message 61 Double letters in part 4, possible use in playfair. (Elonka)

Two-Square

Tri-Square

Four-square

Slidefair

Hill Cipher

Hill cipher: ran 157248 invertible 2x2 matrices against first 96 letters of K4, numbering letters by KRYPTOS alphabet.

Tried alphabet in all shifts. Repeated for last 96 letters of K4. Repeated with standard alphabet. Grading results on occurence of singles, digrams and trigrams.

No interesting results.

Magic square

Message 261 Magic square use on K3(David Wilson)