Cloak: Data Encryption from Thunderhead Software Page: 1 P.O. Box 91, McKeesport, Pa., USA, 15135 (412) 751-4020 Cloak This program is being distributed as Freeware by Thunderhead Soft- ware, Inc. You may distribute it freely, and use it without fees or 'reminders' that Shareware/Begware often throws at you. I do request that you do NOT modify any of the files, or re-pack the archive file. I KNOW there are better archivers out there,but there are also HACKERS and VIRUS-distributors around, and I don't want any of my programs involved in those messes. Thunderhead Software is a small software company in McKeesport, Pen- nsylvania, in the United States, which sells commercial software for a variety of uses. I have enclosed a copy of our August, 1990 cata- log for your perusal. If you have questions, comments, or orders,PLEASE FEEL FREE TO WRITE US at: Cloak: Data Encryption from Thunderhead Software Page: 2 P.O. Box 91, McKeesport, Pa., USA, 15135 (412) 751-4020 Thunderhead Software, Inc. P.O. Box 91 McKeesport, Pa. 15135 DISCLAIMER The ÿauthor of this program warrants that this program will run on his computer when he uses it. ÿNo further warranties exist in relation to this product, ÿstated or implied, on the part of the author. ÿThere is no warranty of suitability or fitness for a particular purpose, nor is there a warranty of merchantability. The author is not responsible for damages, direct or indirect, that arise as a consequence of the use or misuse of this product. This includes, but is not limited to damage to other software, data, and hardware, and claims by other parties. Cloak: Data Encryption from Thunderhead Software Page: 3 P.O. Box 91, McKeesport, Pa., USA, 15135 (412) 751-4020 Cloak: A self-inverting data encryption process. This program was written by Richard Parker. This is the latest 'Freeware', package, with logic number 8462. This package is a small hint at what the REAL (commercial) Crypt is like. What is data encryption? Data encryption is an added measure of security ÿthat ÿyou can add to your confidential files. It ÿwill NOT prevent others with access to your computer from changingÿor erasing your information. What it DOES is prevent others from UNDERSTANDING your data,ÿand making sense out of it. The file can be read, but the contents will be meaningless garbage to unauthorized personnel. Only a person with this particular Cloak package (#8462),ÿAND your pass- word will be able to return the file to it's normal state. Whatÿis a self-inverting data encryption process? Theÿsimplest Cloak: Data Encryption from Thunderhead Software Page: 4 P.O. Box 91, McKeesport, Pa., USA, 15135 (412) 751-4020 methodÿof data encryption: you use the same program to encrypt and decrypt the file. This provides a safe, reversible method of securing your ÿdata. ÿOther systems require 2 or more programs to ÿencode ÿyour data, ÿwhich can lead to disaster when the wrong program is used at the wrong time. Youÿwillÿfindÿa copy of this file called ÿ'guess.me' ÿÿon ÿthis diskette. Try to read it. Use your word processor, or the dos 'type' command. Try any means you can think of to decipher it. Chances are you wouldn't have any idea what the contents are, unless you hadÿthe Cloak program AND the password I used to encrypt the program. The password I used was "Thunderhead" with no spaces. Passwords may be 1 to 78 characters long, with six significant characters. Which six? ÿThat's part of the secret: ÿthe significant ÿcharacters change dependingÿon the length of the password, so in most cases, only the exact password will decrypt the file. (By Comparison, the commercial versions use 6 - 24 significant characters, meaning that Cloak: Data Encryption from Thunderhead Software Page: 5 P.O. Box 91, McKeesport, Pa., USA, 15135 (412) 751-4020 there are many more different ways to encrypt a file.) Cloak will ask you for two filenames: the file to be encrypted and the output file. This should be self-explanatory. To decrypt a file, you simply encrypt it with the same password a secod time. Case in point, to decrypt the 'guess.me'ÿfile, the sourceÿfile ÿwould be 'guess.me'ÿand the target file would be 'original.txt'ÿorÿwhatever filename you wish. ÿThe password is, again, "Thunderhead". ÿYou may tell Cloak this in either of two ways: Cloak guess.me original.txt Thunderhead or Cloak, and then answer the questions appropriately. file to be encrypted: guess.me output file: original.txt password: Thunderhead Cloak: Data Encryption from Thunderhead Software Page: 6 P.O. Box 91, McKeesport, Pa., USA, 15135 (412) 751-4020 After the process is done, Cloak will ask if you wish to erase the source file. BE VERY CAREFUL WITH THIS FEATURE! Cloak'S ERASE FEATURE CANNOT BE ÿUNDONE! ÿMS-DOS unerase utilities, including ÿthe Norton Commander, and PC-Tools can NOT effectively un-erase files erasedÿby the Cloak program. It's best to answer N to this question, andÿuse theÿdosÿ erase or delete command until you are comfortable withÿthis program. How did I encrypt the file originally? I simply typed: Cloak readme.doc guess.me Thunderhead If you wish to try this, keep two things in mind: all files should be inÿthe current dos directory,ÿand the output file must not exist before running Cloak. Cloak: Data Encryption from Thunderhead Software Page: 7 P.O. Box 91, McKeesport, Pa., USA, 15135 (412) 751-4020 Too simple? Afraid someone might guess your password? There is a solution. ÿRun the Cloak program more than once, and use ÿdiff- erent passwords. Example: Cloak readme.doc readme.2 Thunderhead Cloak readme.2 readme.3 RFParker Cloak readme.3 readme.4 wow Now erase readme.doc, ÿreadme.2, and readme.3. The readme.4 file cannot be decrypted unless you do the exact same thing: Cloak readme.4 readme.3 wow Cloak readme.3 readme.2 RFParker Cloak readme.2 readme.doc Thunderhead Change a step, forget a step, or misspell a password, and the data is history. This program is so powerful that I, the author, can not decrypt an encrypted file without both the logic number and the Cloak: Data Encryption from Thunderhead Software Page: 8 P.O. Box 91, McKeesport, Pa., USA, 15135 (412) 751-4020 actual password used. ( In actuality, the shareware release takes under 10,000 PC-Hours to break. The commercial releases take 59,000, 125,000, and infinitely many hours, respectively.) Remember, ÿalso, that you can not unerase a file that Cloak ÿerases, ÿso be careful with that function until you are sure ÿof yourself, and can remember your exact password or passwords. Statistics of 7 August 1990 release of (Shareware) Cloak @ 8462: Test machine: STI-286-12 multispeed machine: Turbo: 12 MHz with a Norton Computing Index of 13.7 Slow: 8 MHz with a Norton Computing Index of 9.0 Hard Drive: 40 Meg ST-251 with W.D. AT-style controller Norton Disk Index of 2.5 in either speed mode Test file: a: old wp program file: 274,384 bytes long ( ed.exe from pc-write 3.0.1) Cloak: Data Encryption from Thunderhead Software Page: 9 P.O. Box 91, McKeesport, Pa., USA, 15135 (412) 751-4020 Cloak.exe: 30,752 bytes long at 03:16: pkzip csum: bcb55792 Test Mean Turbo Mean Slow CPS Turbo CPS Slow (sec) (sec) (C/sec) (C/sec) --------------------------------------------------------------------- copy a b 5.93 5.99 46,270 45,807 cloak a b t 13.13 16.86 20,897 16,274 cmp a b 54.61 56.20 5,024 4,882 Please remember, this is a 'Crippleware/Freeware' Type Program! The commercial versions of Cloak run more quickly, and use a much more sophisticated enrcyption scheme. Commercial versions also allow multiple encryptions and/or multiple passwords, and have a friendly user-interface option, in addition to the command line and 3 question modes. Cloak: Data Encryption from Thunderhead Software Page: 10 P.O. Box 91, McKeesport, Pa., USA, 15135 (412) 751-4020