| Title: | -={ H A C K E R S }=- |
| Notice: | Write locked - see NOTED::HACKERS |
| Moderator: | DIEHRD::MORRIS |
| Created: | Thu Feb 20 1986 |
| Last Modified: | Mon Aug 03 1992 |
| Last Successful Update: | Fri Jun 06 1997 |
| Number of topics: | 680 |
| Total number of notes: | 5456 |
Below is a Vax-Basic program that scrambles any input to something quite scrambled up. I'd like to see if anyone here can figure out a reverse to this, as none of my friend (nor I) can figure out a solution. Here are just two examples of the output of this program: Unencrypted: A Encrypted: AN9CPG Unencrypted: B Encrypted: 7OETMF Those are just two I know off the top of my head. Here is the routine: 10 PRINT "Enter line"; 20 INPUT TEXT$ 40 GOSUB 29000 55 PRINT TEXT$;" encoded is ";X$ 60 GOTO 10 29000 CHANGE TEXT$ TO X% 29005 FOR X% = X%(0%) +1% TO 3% 29006! 29010 X%(X%) = 2% * X%(X%-1%) - X%(X%-1%) / 11% * 11% 29011! 29015 X%(X%) = X%(X%) - X%(X%) / 127% * 127% 29016! 29020 NEXT X% 29021! 29025 X%(7%) = X%(0%) 29026! 29030 IF X%(0%) < 3% THEN X%(7%) = 3% 29031! 29035 FOR X% = 6% TO X%(7%) + 1% STEP -1% 29040 X%(X%) = 127% - X%(7%-X%) 29041! 29045 NEXT X% 29046! 29050 FOR X% = 1% TO 6% 29051! 29055 X%(8%) = 12% * ( (X%+1%) / 2% + 1%) + (-1%) ^ X% 29056! 29060 FOR X1% = 1% TO 6% 29061! 29065 X%(X%) = 2% * X%(X%) + X%(X1%) - X%(X1%) / X%(8%) * X%(8%) 29066! 29070 NEXT X1% 29071! 29075 X%(X%) = X%(X%) + X% * X%(0%) + 101% 29076! 29080 X%(X%) = X%(X%) - X%(X%) / 36% * 36% 29081! 29085 IF X%(X%) < 10% THEN X%(X%) = X%(X%) + 48% ELSE X%(X%) = X%(X%)+ 55% 29086! 29090 NEXT X% 29091! 29095 X$="" 29097 FOR Z%=1% TO 6% 29098 X$=X$+CHR$(X%(Z%)) 29099 NEXT Z% 29100 RETURN 32767 END Well, I wish anyone who attempts it good luck -- and if someone gets it, would they PLEASE mail the routine to EXODUS::MARK Also, please spread this message around to as many notefiles that are appropriate for it. Thank you very, VERY much, and again, good luck. <m>
| T.R | Title | User | Personal Name | Date | Lines |
|---|---|---|---|---|---|
| 105.1 | FKPK::KONING | Mon Apr 01 1985 17:34 | 17 | ||
That's not an encryption, that's a one-way (or maybe two-way) hash. Encryption implies the ability to decrypt, and the ability to supply a key that changes the plaintext->cyphertext mapping, neither of which you have here. Is there some mathematical basis to this program, or is it just a random algorithm? Knuth's statement "random numbers should not be generated with an algorithm chosen at random" applies as much or more so to encryption or hash functions. Does this algorithm have any desirable properties that currently well-known/accepted hash functions (e.g. DES, Purdy) do not have? Sorry if I'm being overly picky on something that was just proposed as a fun puzzle and not a serious piece of code. The problem is that sometimes toys are mistaken for serious code and make it into products, and afterwards cause serious security problems. Paul | |||||
| 105.2 | BOOKIE::PARODI | Wed Apr 03 1985 14:03 | 7 | ||
The coding techniques used in this thing serve as a fine example of encryption! Using the same identifier (X%) for a scalar and an array... tch tch JP | |||||
| 105.3 | VIKING::WASSER_1 | Wed Apr 03 1985 15:59 | 8 | ||
I am trying to convert this to 'C' but I can't find a manual for VAX BASIC. What does the CHANGE <string> TO <array> do? Does it store the string length in array[0]? What gets put in the unused elements (if any) of the array? -John A. Wasser "Real hackers barf at algorithms described in BASIC" | |||||
| 105.4 | EXODUS::MARK | Wed Apr 03 1985 21:25 | 21 | ||
Ok, the CHANGE takes the string, puts its length in X(0), and each ascii character code of each character in the string and puts them in X(y). CHANGE may also be in the basic help file. This algorhythm doesn't use random numbers at all. The routine was not 'taken' from any product if that is what you mean. I just stumbled upon it and couldn't figure it out. I appreciate the effort you are putting in this. I really hope to find some way to undo it. You will have to forgive my little knowledge of encryption/algorhythms because this is the first time I really ever saw something like this. Again, thanks -- and keep up the good work <m> | |||||
| 105.5 | SMILEY::MUNYAN | Thu Apr 04 1985 16:47 | 8 | ||
Can I ask where you got that... The company I used to work for used that exact piece of code with the same variable names to produce database keys. The original algorithm was based on an algo that appeared many years ago in the communications of the ACM. I remember using that code as far back as 1974. Steve | |||||