Re: The crazy encryption madmans codebook


<jt64@xxxxxxxx> wrote in message
news:1172820109.932982.192810@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On 1 Mar, 17:18, "Joseph Ashwood" <ashw...@xxxxxxx> wrote:
<j...@xxxxxxxx> wrote in message

news:1172793500.867394.322540@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

So your concept is to move the ancient concept of a codebook into a
database? It is ECB with encryption replaced by a lookup.

The overall security is as strong as what I will call the chaining mode
within and between the messages. By this I mean that is "orcdriffle"
always
translates to "telephone" the construct will leak and quickly fall apart.


No Joe i meant more like this

Actually you seem to have failed to understand what I was saying.

Consider 3 functions:
lp(string) looks up the given phrase in a database and returns a unique but
constant integer identifier for the word
li(integer) looks up the given integer identifier and returns a unique but
constant phrase associated with it
c(...) takes an integer as an input, computer a prp function on that input
and returns the value, both input and output are constrained to the possible
return values of li. Such that c' exists where x=c'(c(x)) for all valid x

This system of 3 functions is more powerful than your database lookup
system. There are 3 possible conditions:
c() takes only an integer (c(i))
c() takes an integer and a permutation identifier (key) (c(i,k))
c() takes an integer, a permutation identifier, and some state information
that it outputs for later input (c(i,k,v))

lp, li, c(i) combined are provably at least as powerful as your system as
they can express any system in your design. It is also trivally provable
that c(i) is less powerful than c(i,k)

lp,li,c(i,k) are trivially provable to be a cipher in ECB mode. As such they
fail in all the same ways as ECB with one major, and devastating exception,
each output represents a phrase and as such break accuracy can be quantified
more easily.

lp,li,c(i,k,v) represents the modification you proposed where k has length
0. c(i,k,v) has security equal to c(f(i,v),k) and that the security lies in
f(i,v) and c(i,k), seperating these out your multiplier has no entropic
input and as such for security purposes reduces to an identity, so the
security reduces to c(i,k) for which you have a 0 length k, so it reduces to
c(i) which is horrifying insecure.

As a result your entire construct, as it stands is extremely insecure. Also
it will be necessary to have a database with a prime number of entries
simply in order to make your proposal as difficult as possible to break
(still trivial though), so your proposed modification (in the other message)
actually lowers the security further because it is trivially provable that k
and k+1 cannot be prime for k>2.

So your entire system results in equivalence to a codebook, and your
modification to improve it actually weakens it.
Joe


.

Relevant Pages

  • Re: The crazy encryption madmans codebook
    ... It is ECB with encryption replaced by a lookup. ... lplooks up the given phrase in a database and returns a unique but ... constant integer identifier for the word ... chas security equal to c,k) and that the security lies in ...
    (sci.crypt)
  • Re: The crazy encryption madmans codebook
    ... It is ECB with encryption replaced by a lookup. ... lplooks up the given phrase in a database and returns a unique but ... constant integer identifier for the word ... chas security equal to c,k) and that the security lies in ...
    (sci.crypt)
  • Re: setting a password on a button on the switchboard
    ... Could you send me the sample database for the fourth option (4. ... > Security in an Access database can probably be broken down into two big ... > points about being easier than User Level Security, ... > What type of data are you trying to protect? ...
    (microsoft.public.access.forms)
  • Re: access 2003
    ... security in access 2003. ... The data will go on the server and the program database ... than the alternative of creating an mde file. ... MDW file from the written record. ...
    (microsoft.public.access.conversion)
  • Re: access 2003
    ... security in access 2003. ... The data will go on the server and the program database ... than the alternative of creating an mde file. ... MDW file from the written record. ...
    (microsoft.public.access.conversion)