> -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of > Michael Rogers > Sent: Tuesday, November 28, 2006 1:29 AM > To: theory and practice of decentralized computer networks > Subject: Re: [p2p-hackers] Re: security and protocols > > Alex Pankratov wrote: > > Block cipher. I assume it's a typo, since you said you were > using TwoFish. > > Using a block cipher in CTR mode creates a stream cipher (ie it > generates a keystream that you XOR with the plaintext to produce the > ciphertext).
Right, so it allows saving up to 16 bytes on padding. On other hand it means leaking more information to the observer, and might simplify known-plaintext attacks. > > Using CTR instead of any other chaining mode (excluding > ECB) has exactly one > > benefit - the counter field can be reused for replay protection. > > There's another benefit that's relevant to the question of > UDP vs TCP: > it's easy to decrypt blocks that arrive out of order. I'm not sure I understand. How is *not* using CTR makes it hard to handle out-of-order delivery ? Assuming we are still talking about application level protocols riding on top of TCP/UDP. Alex _______________________________________________ p2p-hackers mailing list [email protected] http://lists.zooko.com/mailman/listinfo/p2p-hackers
