Letters coded by groups of symbols...?

[Nick Pelling <incoming@xxxxxxxxxxxxxxxxx>]

Hi everyone,

I've been trying to determine in what way the VMS' low-entropy symbols 
might group together to form something closer to a normal-entropy stream. 
The underlying assumption is that the apparent impenetrability of the VMS' 
code owes more to obfuscation than to its cipher structure - something like 
Vigenere's "Alphabeth Northmanique" [1].

The following is only a preliminary analysis, but I believe it shows some 
promise already. I should also point out that I assume that spaces in the 
text are not necessarily coincident with plaintext word boundaries.

There appear to be three classes of gallows usage:-
(a) o + gallows
	ot	ok	op	of	octh	ockh	ocph	ocfh
(b) qo + gallows
	qot	qok	qop	qof	qocth	qockh	qocph
(c) gallows everywhere else

The (c) gallows don't seem to fit any obvious pattern I've tried on them, 
so my working hypothesis is that they are instances of some kind of 
replacement code or cipher, under which they get replaced by a 
(non-gallows) character (or character-sequence).

Then, most of the text forms itself into groups very naturally:-
	al	aiii	ain	aiin 	ar	air	am
	ol	oiii	oir	oiir	or	oir
	ee	eo	ea	ey	es
	ch	cho		<-- "normal picnic tables"
	Sh	Sho		<-- "embellished picnic tables"

However, there are some frequent singletons which seem to have their own 
rules:-
	d	y	s	m

And finally, there are some rarer singletons which don't quite fit the 
pattern:-
	q	o

Here are my observations having tried this scheme out on eight pages (all 
Language A botanicals):-
-	The first 8-10 characters of each page often don't fit
-	The last 1-3 characters of many lines often don't quite fit
-	EVA "d" and EVA "y" seem to work as if they were Latin shorthand
-	Many of the groups could well be duplicates of each other
-	This gives an underlying alphabet size of between 36 and 43
-	Doubled letters appear in many places

Cheers, .....Nick Pelling.....

[1]   http://www.chass.utoronto.ca/~wulfric/rentexte/vigenere/chif_f338r1.jpg