/ solitaire: http://www.schneier.com/solitaire.html

/ card data:

N:1+B:1+A:52                                     / count, jokers
J[`A`B]:1 2{,/@[!N;(y+x)!N;,;y]_di y}'\:!N       / joker matrices

/ solitaire algorithm:

h:{x[z;k[y]@#z]!26}                              / data +|- keystream
k:{p'1_ y((~A>p@)s/s@)\x}                        / keystream
a:{x J.A x?A}                                    / move joker A
b:{x J.B x?B}                                    / move joker B
t:{,/|(0,0 1+{x@<x}x?/:A,B)_ x}                  / triple cut
r:{,/1!|(0,(1+y),B)_ x}                          / cut 
c:{r[x]A&*|x}                                    / count cut
s:c t b a@                                       / solitaire step
p:{x 1+A&*x}                                     / pop a character

/ user interface:

f:_.2*#:                                         / count divided by 5
v:{(5*f x)#x,:4#"X"}                             / vector of fives
m:{(f[x],5)#x}                                   / matrix of fives
u:{{x@&(x>64)&x<91}x-32*(x>96)&x<123}            / upper-case
i:-65+u@_ic                                      / char -> int
o:_ci 65+                                        / int -> char

/ entry points:

e:{m o h[+;x]i v y}                              / encrypt
d:{o h[-;x]i@,/y}                                / decrypt
g:{{r[s x;y]}/[x;i y]}                           / generate deck

/ test

C:g[!N]"cryptonomicon"
E:e[C]
D:d[C]

D E"this is a string"