block-cipher weakness? - was: Re: twofish keysize

[Atom 'Smasher']

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On Thu, 22 Apr 2004, Per Tunedal Casual wrote:
> On average 32 GB is the limit i.e. the probability is 50 % that an
> adversary finds two identical blocks. But you might have bad luck and
> he might find two identical blocks in somewhat smaller files.
===============================

can someone explain to me why/how it's a vulnerability if an attacker
finds more than one block of cipher text that are the same?

would there be a benefit of using a stream cipher for large files?

is there a reason why OpenPGP doesn't specify any stream ciphers?

thanks...


	...atom

 _________________________________________
 PGP key - http://atom.smasher.org/pgp.txt
 3EBE 2810 30AE 601D 54B2 4A90 9C28 0BBF 3D7D 41E3
 -------------------------------------------------

                    _
                  _(_)_                          wWWWw   _
      @@@@       (_)@(_)   vVVVv     _     @@@@  (___) _(_)_
     @@()@@ wWWWw  (_)\    (___)   _(_)_  @@()@@   Y  (_)@(_)
      @@@@  (___)     `|/    Y    (_)@(_)  @@@@   \|/   (_)\
       /      Y       \|    \|/    /(_)    \|      |/      |
    \ |     \ |/       | / \ | /  \|/       |/    \|      \|/
    \\|//   \\|///  \\\|//\\\|/// \|///  \\\|//  \\|//  \\\|//
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.4 (FreeBSD)
Comment: What is this gibberish?  -  http://atom.smasher.org/links/#digital_signatures

iEYEARECAAYFAkCNPs8ACgkQnCgLvz19QeNY7gCdExdCYs5LFApqwkVEvOA89Tv4
JjYAnjMB7gTyMSAQFrkEeQM7JrdAtj6Q
=FngB
-----END PGP SIGNATURE-----