
                                                                              
  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 author of this program warrants that this program will run on     
  his computer when he uses it.  No further warranties exist in relation     
  to this product, stated or implied, on the part of the author.  There     
  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 that you can add to your confidential files. It will NOT        
  prevent others with access to your computer from changingor erasing        
  your information. What it DOES is prevent others from  UNDERSTANDING        
  your data,and 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),AND your  pass-        
  word will be able to return the file to it's normal state.                  
                                                                              
       Whatis a self-inverting data encryption process?  Thesimplest        
                                                                              
                                                                              
  Cloak: Data Encryption from Thunderhead Software                Page: 4     
  P.O. Box 91, McKeesport, Pa., USA, 15135   (412) 751-4020                   
                                                                              
  methodof data encryption:  you use the same  program to encrypt and        
  decrypt the  file.  This  provides  a  safe,  reversible  method  of        
  securing  your data. Other  systems  require  2  or  more programs        
  to encode your  data, which  can  lead to disaster when the wrong        
  program is used at the wrong time.                                          
                                                                              
       Youwillfinda copy of this file called 'guess.me' on this        
  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 hadthe        
  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?  That's part of the secret: the significant characters        
  change dependingon 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'file, the sourcefile would       
  be 'guess.me'and the target file would be 'original.txt'orwhatever       
  filename you wish. The password is, again, "Thunderhead".  You  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 UNDONE! MS-DOS unerase utilities, including the        
  Norton  Commander, and  PC-Tools  can NOT effectively un-erase files        
  erasedby the Cloak program. It's best to answer N to this question,        
  anduse thedos erase or  delete  command until you are comfortable        
  withthis 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 inthe current dos directory,and 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. Run the Cloak program more than once, and use diff-        
  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, readme.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, also,        
  that you can not unerase a file  that  Cloak erases, so be careful        
  with that function until you are sure of 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                   
                                                                              
