Bacon cipher

Bacon cipher is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

Bacon's cipher is a method of steganography created by Francis Bacon. This task is to implement a program for encryption and decryption of plaintext using the simple alphabet of the Baconian cipher or some other kind of representation of this alphabet (make anything signify anything).

The Baconian alphabet:

a   AAAAA   g     AABBA   n    ABBAA   t     BAABA
b   AAAAB   h     AABBB   o    ABBAB   u-v   BAABB
c   AAABA   i-j   ABAAA   p    ABBBA   w     BABAA
d   AAABB   k     ABAAB   q    ABBBB   x     BABAB
e   AABAA   l     ABABA   r    BAAAA   y     BABBA
f   AABAB   m     ABABB   s    BAAAB   z     BABBB

J

Implementation:

<lang J>alfa=: 'ABCDEFGHIKLMNOPQRSTUWXYZ' beta=: 26{.(}.~i.&'A')a. norm=: ([ -. -.)&alfa@(rplc&('JIVU'))@toupper enca=:(5#2),@:#:alfa i. norm gena=: ]`((,:tolower)@(beta {~ 26 ?@#~ #))}

encrypt=: gena@enca@norm decrypt=: alfa {~ _5 #.\ 90 < a.&i.</lang>

We use random letters as the basis for our steganography and we use case to represent "font".

Example use:

<lang J> encrypt 'this is a test' nWVkJAPkamEuUJIeTGKnUsTVRfAWWuNBIIHdEIcOAPuTBeXKQduQAdU

  encrypt 'this is a test'

sFLkBQKqqaQsGGXzAXQsKlZFBcILRlUIRAQaEQoNUBcHIhFTWbeRAlM

  decrypt encrypt 'this is a test'

THISISATEST</lang>