david@oahu.cs.ucla.edu (David Dantowitz) (02/07/90)
Does anyone have info on using eexec. An older copy of the red book
mentioned it (briefly) but the new version has nothing.
Thanks,
David
David Dantowitz
david@cs.ucla.edu
Singing Barbershop when I'm not computing...woody@rpp386.cactus.org (Woodrow Baker) (02/08/90)
In article <31604@shemp.CS.UCLA.EDU>, david@oahu.cs.ucla.edu (David Dantowitz) writes: > > > Does anyone have info on using eexec. An older copy of the red book > mentioned it (briefly) but the new version has nothing. > Yep. A routine has been posted on the net to decrypt the eexec data into plain text, and also convert plain text to eexec data. I've got it. Basicaly eexec is an encryption algorthym that uses a linear congruent random number and uses the byte of data and XOR's them together, then uses the incoming data to compute the next random number. you might try this nclude "stdio.h" /* routine takes an encrypted eexec file and creates a decrypted file. By Woody Baker */ FILE *infile,*outfile; main(argc,argv) char *argv[]; int argc; { int first =4; int state=0xD971; int c; char decrptd; if(argc !=3) { printf("usage: decrpt infile outfile\n"); exit(0); }; infile=fopen(argv[1],"rb"); outfile=fopen(argv[2],"wb"); while(fscanf(infile,"%2x",&c)>0) { decrptd= c ^ (state >>8); if(first !=0) { first--; } else { fputc(decrptd,outfile); } state=state + c; state=state * 0xCE6D; state=state + 0x58BF; } fclose(infile); fclose(outfile); } I think this is the working version that I use. Hope this helps. Cheers Woody
merlyn@iwarp.intel.com (Randal Schwartz) (02/08/90)
In article <17883@rpp386.cactus.org>, woody@rpp386 (Woodrow Baker) writes: | Yep. A routine has been posted on the net to decrypt the eexec data into | plain text, and also convert plain text to eexec data. I've got it. Basicaly | eexec is an encryption algorthym that uses a linear congruent random number | and uses the byte of data and XOR's them together, then uses the incoming | data to compute the next random number. | | you might try this [C code deleted] and, (blowing the dust off this crufty old code....phhhhehhhhehhwwww...) if you don't want to go as *fast* as the C program, or want to experiment with both encrypting and decrypting, try this GNU Emacs lisp code. Once again, to immediately dispel the spooks... I WROTE THIS LISP CODE FROM AN ALGORITHM POSTED ON THE NET. I DID NOT REVERSE-ENGINEER THE ROMS. I *do* take credit for implementing the elisp, though, as crafty as it is, and have tried a few examples to know that it does indeed work. Enjoy. (Code follows signature...) Just another GNU Emacs and postscript hacker :-), -- /=Randal L. Schwartz, Stonehenge Consulting Services (503)777-0095 ==========\ | on contract to Intel's iWarp project, Beaverton, Oregon, USA, Sol III | | merlyn@iwarp.intel.com ...!any-MX-mailer-like-uunet!iwarp.intel.com!merlyn | \=Cute Quote: "Welcome to Portland, Oregon, home of the California Raisins!"=/ ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; cut here ;;; Postscript eexec support routines ;;; LastEditDate "Thu Jul 20 14:59:08 1989" ;;; Copyright (c) 1989 by Randal L. Schwartz. All Rights Reserved. ;;; This code may be freely distributed according to the GNU Public License (defconst hex-string-to-int-table (let ((ht (make-vector 256 nil))) ; nil gives error at + if out-of-range (mapcar (function (lambda (pair) (aset ht (nth 0 pair) (nth 1 pair)))) '((?0 0) (?1 1) (?2 2) (?3 3) (?4 4) (?5 5) (?6 6) (?7 7) (?8 8) (?9 9) (?a 10) (?b 11) (?c 12) (?d 13) (?e 14) (?f 15) (?A 10) (?B 11) (?C 12) (?D 13) (?E 14) (?F 15))) ht) "Table used by hex-string-to-int.") (defun hex-string-to-int (str) "Convert STRING to an integer by parsing it as a hexadecimal number." (let ((result 0)) (mapcar (function (lambda (ch) (setq result (+ (lsh result 4) (aref hex-string-to-int-table ch))))) str) result)) (defun byte-to-hex-string (byte) "Convert BYTE to a two-chararacter string by printing it in hexadecimal." (format "%02x" byte)) (defconst eexec-const-init (hex-string-to-int "d971") "Used by eexec-endecode. Initial value for state machine.") (defconst eexec-const-mult (hex-string-to-int "ce6d") "Used by eexec-endecode. Multiplier value for state machine.") (defconst eexec-const-add (hex-string-to-int "58bf") "Used by eexec-endecode. Adder value for state machine.") (defconst eexec-const-seed (concat (mapcar 'hex-string-to-int '("17" "ec" "9c" "f3"))) "Used by eexec-encode. A known good seed from uartpatch.ps.") (defun eexec-decode () "Decode the first eexec string in the current (possibly narrowed) buffer. Result is displayed in a temp buffer." (interactive) (with-output-to-temp-buffer "*eexec-decode-output*" (goto-char (point-min)) (search-forward "eexec") (let (str) (while (re-search-forward "[ \t\n]*\\([0-9a-fA-F][0-9a-fA-F]\\)" nil t) (setq str (cons (buffer-substring (match-beginning 1) (match-end 1)) str))) (setq str (nreverse str)) (setq str (eexec-endecode (concat (mapcar 'hex-string-to-int str)))) (princ "Seed: ") (princ (apply 'concat (mapcar 'byte-to-hex-string (substring str 0 4)))) (princ "\nText:\n") (princ (substring str 4))))) (defun eexec-encode (start end &optional seed) "Encode text from START to END (region if interactive). Result is displayed in a temp buffer. If optional SEED is passed as a four-character string, use it for initial state, else use the known good seed (the current value of eexec-const-seed)." (interactive "r") (with-output-to-temp-buffer "*eexec-encode-output*" (let ((i 0)) (princ "currentfile eexec\n") (mapcar (function (lambda (ch) (princ (byte-to-hex-string ch)) (if (< (setq i (1+ i)) 32) nil (princ "\n") (setq i 0)))) (eexec-endecode (concat (or (and (stringp seed) (= (length seed) 4) seed) eexec-const-seed) (buffer-substring start end)) t)) (if (> i 0) (princ "\n"))))) (defun eexec-endecode (str &optional encode) "Decode STR (or encode if optional ENCODE is non-nil), returning result. If decoding, you will probably want to toss the first four bytes, but they are returned anyway so that you may reencode a decoded string for verification." (let ((state eexec-const-init) outbyte) (concat (mapcar (function (lambda (inbyte) (setq outbyte (logxor inbyte (lsh state -8)) ;; can these next three be combined for speed? state (logand 65535 (+ state (if encode outbyte inbyte))) state (logand 65535 (* state eexec-const-mult)) state (logand 65535 (+ state eexec-const-add))) outbyte)) str)))) ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; cut here
david@oahu.cs.ucla.edu (David Dantowitz) (02/09/90)
Okay, now I can encode and decode eexec format. Now, can someone provide the proper syntax and an example use? Thanks. David Dantowitz david@cs.ucla.edu Singing Barbershop when I'm not computing...