in reply to Safe symmetric encryption - Crypt::CBC + Crypt::Blowfish?

My understanding of crypto is, regardless of the algorythm you NEVER USE THE SAME KEY TWICE. Public key systems get around this though. You aren't.

--
I'm not belgian but I play one on TV.

  • Comment on Re: Safe symmetric encryption - Crypt::CBC + Crypt::Blowfish?

Replies are listed 'Best First'.
Re: Re: Safe symmetric encryption - Crypt::CBC + Crypt::Blowfish?
by thraxil (Prior) on Feb 08, 2003 at 20:39 UTC

    never use the same key twice for a one-time pad. other symmetric algorithms are designed to allow you to reuse keys (with some eventual loss of security; see the other posts below this for more). public key systems just get around key distribution problems.

    anders pearson

      A Block cipher in CBC mode allows you to reuse the key. A Stream cipher is no different than a one-time pad in this respect. RC4 is a stream cipher. Think of a stream cipher as a condensed instruction on how to generate the one-time pad. The key is just a seed for a pseudo-random number generator.