Re: 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?

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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	[reply]
Re: Re: Re: Safe symmetric encryption - Crypt::CBC + Crypt::Blowfish? by John M. Dlugosz (Monsignor) on Feb 09, 2003 at 05:06 UTC
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.	[reply]