[GnuPG-users] identical files -> non-identical encrypted files

[Jean-David Beyer]

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Kiss Gabor (Bitman) wrote:
>>> The password is not random therefore every time you encrypt the same
>>> plaintext you got the same cryptfile.
>> No, you won't.  All sound encryption schemes use a bit of random to
>> make the resulting ciphertext different.  In the easiest case this is
>> called a salt and used to stop dictionary attacks.  For example, such a
>> salt has been used for 25 years or so on all Unix systems to protect
>> the login password.
>> 
>>> (The opposite would cause big problems in a disk encryption system.
>>> :-)
>> No.  Different ciphertexts may yield the same plaintext.
> 
> A test speaks for itself:
> 
> $ cat /etc/passwd | aespipe | md5sum Password: 
> 9220c2e1d5a5a83710d020b04c306c24  - $ cat /etc/passwd | aespipe | md5sum 
> Password: 9220c2e1d5a5a83710d020b04c306c24  - $
> 
?????

Apples and Oranges. Consider:

$ gpg --output test1.gpg --encrypt --recipient jeandavid8 [at] verizon [dot]
net /etc/passwd
$ gpg --output test2.gpg --encrypt --recipient jeandavid8 [at] verizon [dot]
net /etc/passwd

$ od -c test1.gpg | less
0000000 205 004 016 003   y 037 301 373 022   N 006   c 020 017 376   $
0000020 353   }   _   W  \r   - 314 030   B 303   z 226 223 340   S 313
0000040 375   0   4   $   ) 254   a  \0 377 364   /   <   ; 222   ( 315
0000060   / 006 213 004 221 264   <   a 255 247   B 275  \a 301 264   Q
0000100 203 250   . 257  \0   Q 376 232 312 266   3   . 321 022   b 215
0000120 374   $ 241   ` 256   j   D 351   a 246 326   ? 223 313 210   $
0000140 321 023 032 244 262 273 246 215   -   i   b   >   m   " 255 313
0000160 035 240 337 230  \v   B 327  \r 265 362 255 271   (   ?   b 202
0000200 034 332 371   T 250 310   = 223 211 236 304   U 334 206   z   `


$ od -c test2.gpg | less
0000000 205 004 016 003   y 037 301 373 022   N 006   c 020 017 376   8
0000020   A 217   B   R 377 264   b   y 361   X 243   \ 316   x 346 246
0000040   A 016 257 310   Y 032 265   & 022   g 016 327 274 276 364 337
0000060   )   b 211 354  \f 005 354 002 001 224 251   1   )   S  \a 266
0000100   + 312 004   " 310 315 354   }   A 206   p   . 242 332 214 305
0000120 226   T 255 304   d 235   #   B 240  \f 020   [ 003   x 023 305
0000140 210   l   H 247   1 334   ( 216   6 257   H 314   A 023 323 363
0000160   = 361   9   V   U   '   c   7   s 247 372   9 306 202 342 203
0000200   l   K   Y 323   Y   z 372   ~  \r  \v 270   o   J   } 272   1


- --
  .~.  Jean-David Beyer          Registered Linux User 85642.
  /V\  PGP-Key: 9A2FC99A         Registered Machine   241939.
 /( )\ Shrewsbury, New Jersey    http://counter.li.org
 ^^-^^ 14:25:01 up 1 day, 17:17, 5 users, load average: 4.04, 4.14, 4.22
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