Re: Encryption algorithm

From: Peter E.C. Dashwood (dashwood_at_enternet.co.nz)
Date: 01/10/04 

Date: Sat, 10 Jan 2004 12:22:51 +1300

That's very interesting, Russell.

I actually "invented" this technique based on my knowledge of Boolean
Algebra.

I didn't realise it was a standard way of doing it.

The XOR will certainly give you back what you started with, but I need to
think some more (and do some tests, which I currently don't have time for)
before I can be persuaded that there is no need for the decrypt.

Trailing spaces SHOULD not be a problem and they SHOULDN'T encrypt to the
same character. (At least, if they do, then I have got it horribly wrong
<G>.)

As for being broken, yes, it is not an algorithm that could be used for
matters of national security, but it is WAY better than a straight
transformation...

Pete.

(Top post, nothing below.)

"Russell Styles" <rNwOsS0P2A0M2@comcast.net> wrote in message
news:n9idnZb92_Yws2KiRVn-gg@comcast.com...
> I also use this method, but be aware that it can be broken. Ie, if
you
> use
> it to encrypt a password in a configuration file, it will likely have
> trailing spaces,
> which would be the same every time.
>
> But it is quick and easy.
>
> Note that you don't need to differentiate between encrpt and decrypt.
> It
> works both ways. Eg, if you do it twice with the same password, you get
> the original clear text back.
>
>
>
> "Peter E.C. Dashwood" <dashwood@enternet.co.nz> wrote in message
> news:3ffc7d3e_6@news.athenanews.com...
> >
> > "Vik Mehta" <aul1231@yahoo.com> wrote in message
> > news:2df8b8ca.0401070700.67c3ec95@posting.google.com...
> > > I am looking for a simple encryption algorithm to encrypt a 13
> > > character alphanumeric string in a COBOL program. Any help will be
> > > appreciated.
> > >
> >
> > Presumably you want the encryption as a COBOL Subroutine?
> >
> > You will need a COBOL compiler that supports the XOR function.
> >
> > (Microfus and Fujitsu do.)
> >
> > "Here's one I prepared earlier..." (MUCH earlier...over 6 years ago, in
> > fact. It works extremely well despite being simple, and is ideal for
short
> > strings that need encryption before writing to a database or file (like
> > passwords).)
> >
> > Remove anything in square brackets "[...]" before compiling.
> >
> > IDENTIFICATION DIVISION.
> > PROGRAM-ID. 'HERACrpt'.
> > *AUTHOR. Peter E. C. Dashwood.
> > * This program encrypts/decrypts an 8 byte password.
> > *
> > *DATE_WRITTEN. August 1997.
> > ENVIRONMENT DIVISION.
> > configuration section.
> > source-computer. IBM-PC.
> > object-computer. IBM-PC.
> > *------------------------ DATA DIVISION ----------------------
> > DATA DIVISION.
> > WORKING-STORAGE SECTION.
> > 01 encryption-key pic x(8) value 'ANYTHING'.
> >
> > [You can set this key to be any character string you like. My
applications
> > do not use "ANYTHING"... It must be the same length as the field you
wish
> to
> > encrypt, so in your case you need to make it 13 bytes and set a value in
> it.
> > (I suggest: ANYTHINGULIKE while you are testing it...<G> This
encryption
> > key can be any combination of characters you like. You don't have to
> > remember it, but you should make sure that the source code of your
> > encryption module is not freely available, for obvious reasons. (You
could
> > save it as an encrypted WORD document <G>)]
> >
> > 01 xor-return-code pic s9(4) comp-5.
> > 01 hex-table.
> > 12 filler pic x value '0'.
> > 12 filler pic x value '1'.
> > 12 filler pic x value '2'.
> > 12 filler pic x value '3'.
> > 12 filler pic x value '4'.
> > 12 filler pic x value '5'.
> > 12 filler pic x value '6'.
> > 12 filler pic x value '7'.
> > 12 filler pic x value '8'.
> > 12 filler pic x value '9'.
> > 12 filler pic x value 'A'.
> > 12 filler pic x value 'B'.
> > 12 filler pic x value 'C'.
> > 12 filler pic x value 'D'.
> > 12 filler pic x value 'E'.
> > 12 filler pic x value 'F'.
> > 01 filler redefines hex-table.
> > 12 hex-values pic x occurs 16
> > indexed by hv-x1.
> >
> > 01 ws-byte-stuff.
> > 12 filler pic x.
> > 12 lod-byte pic x.
> > 01 ws-binary redefines ws-byte-stuff pic s9(4) comp.
> >
> > 01 quotient pic 99.
> > 01 rem pic 99.
> >
> > 01 num pic s9(5) comp-5.
> >
> > 01 two-bytes.
> > 12 hod-hex pic x.
> > 12 lod-hex pic x.
> >
> > 01 work-string.
> > 12 ws-char pic x occurs 16
> > indexed by ws-x1.
> > 01 xor-len pic s9(9) comp-5.
> >
> >
> > LINKAGE SECTION.
> >
> > [The module takes a single parameter that includes a return code, an
> > indication whether to ENCRYPT or DECRYPT (there's not much point
> encrypting
> > stuff if you can't decrypt it...) and a passed string that will be 26
> bytes
> > in your case (It is twice the length of the string you want encrypted,
as
> it
> > must return each encrypted character as a hex byte.i.e. 2 bytes per byte
> of
> > source)]
> >
> > 01 encryption-block.
> > 12 eb-return pic x.
> > 88 eb-ok value zero.
> > 88 eb-bad-action value '1'.
> > 88 eb-bad-char value '2'.
> > 12 eb-action pic x.
> > 88 HeraEncrypting value 'E'.
> > 88 HeraDecrypting value 'D'.
> > 12 eb-string pic x(16).
> >
> > PROCEDURE DIVISION USING Encryption-block.
> > MAIN SECTION.
> > a000.
> > move zero to xor-len
> > inspect eb-string
> > tallying xor-len for
> > characters BEFORE space
> >
> > evaluate TRUE
> > when HeraEncrypting
> > perform xorit
> > perform asc2hex
> > when HeraDecrypting
> > perform hex2asc
> > perform xorit
> > when other
> > set eb-bad-action to TRUE
> > end-evaluate
> > .
> > a999.
> > exit program.
> > *--------------------------------------------------------
> > xorit section.
> > x000.
> >
> > CALL "CBL_XOR"
> > USING encryption-key
> > eb-string
> > BY VALUE xor-len
> > RETURNING xor-return-code
> > END-CALL
> > if xor-return-code = zero
> > set eb-ok to TRUE
> > else
> > set eb-bad-char to TRUE
> > end-if
> > .
> > x999.
> > exit.
> > *--------------------------------------------------------
> > asc2hex section.
> > ah000.
> > move eb-string to work-string
> > move spaces to eb-string
> > perform
> > varying ws-x1
> > from 1
> > by 1
> > until ws-x1 > xor-len
> > move low-values to ws-byte-stuff
> > move ws-char (ws-x1) to lod-byte
> > divide 16 into ws-binary
> > giving quotient
> > remainder rem
> > add 1 to quotient
> > add 1 to rem
> > move hex-values (quotient) to hod-hex
> > move hex-values (rem) to lod-hex
> > string
> > eb-string
> > delimited by space
> > two-bytes
> > delimited by size
> > into eb-string
> > end-string
> > end-perform
> > .
> > ah999.
> > exit.
> >
> > *--------------------------------------------------------
> > hex2asc section.
> > ha000.
> > move eb-string to work-string
> > move spaces to eb-string
> > perform
> > varying ws-x1
> > from 1
> > by 1
> > until ws-x1 > xor-len
> > move low-values to ws-byte-stuff
> > set hv-x1 to 1
> > search hex-values
> > at end set eb-bad-char to true
> > go to ha999
> > when hex-values (hv-x1) = ws-char (ws-x1)
> > set num to hv-x1
> > subtract 1 from num
> > multiply num by 16 giving ws-binary
> > end-search
> > set ws-x1 up by 1
> > set hv-x1 to 1
> > search hex-values
> > at end set eb-bad-char to true
> > go to ha999
> > when hex-values (hv-x1) = ws-char (ws-x1)
> > set num to hv-x1
> > subtract 1 from num
> > add num to ws-binary
> > end-search
> > string
> > eb-string
> > delimited by space
> > lod-byte
> > delimited by size
> > into eb-string
> > end-string
> > end-perform
> > divide xor-len by 2 giving xor-len
> > .
> > ha999.
> > exit.
> >
> >
> > *---------------- END OF PROGRAM 'HERAcrpt' ----------------
> >
> >
> >
> > > Thanks,
> > > Vik
> >
> > You're welcome...
> >
> > Pete.
> >
> >
>
>

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