Re: Why is blowfish so slow? Other fast algorithms?
At 02:00 AM 1/22/96 -0500, David Mazieres wrote:
Failing that, can anyone suggest other secure, preferably unpatented, shared-key encryption algorithms that could encrypt at ethernet speeds (1 MByte/sec) without using most of the CPU on a fast Pentium or equivalent processor?
RC4 is of course unpatented and faster than anything else. Of course the name RC4 is trademarked, so you could simply call it "the well known algorithm" in your documentation and give the algorithm explicitly. RSA's present legal gimmicks seem to me to be based on the "trade secret" that RC4 really is the well known algorithm, so if you refrain from using the name "RC4", you should be OK. (I am not a lawyer.) T
Thanks a lot, David
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In article <199601221601.IAA14610@mailx.best.com> "James A. Donald" <jamesd@echeque.com> writes:
From: "James A. Donald" <jamesd@echeque.com> Date: Mon, 22 Jan 1996 19:56:43 -0800 X-From-Line: jamesd@echeque.com Mon Jan 22 10:59:02 1996 X-Sender: jamesd@best.com X-Mailer: Windows Eudora Version 2.1 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Lines: 32
At 02:00 AM 1/22/96 -0500, David Mazieres wrote:
Failing that, can anyone suggest other secure, preferably unpatented, shared-key encryption algorithms that could encrypt at ethernet speeds (1 MByte/sec) without using most of the CPU on a fast Pentium or equivalent processor?
RC4 is of course unpatented and faster than anything else. Of course the name RC4 is trademarked, so you could simply call it "the well known algorithm" in your documentation and give the algorithm explicitly.
The problem with RC4 is that it works in OFB only. If I need data integrity in the face of known plaintext, I will need to compute a MAC in paralell with the encryption which could significantly slow things down. With a block cypher in CFB, I can just re-encrypt the last block of data. That said, OFB has the advantage that I can overlap computation of the RC4 stream with I/O, which might be a win for me. Are there any MACs significantly faster than say ~50 cycles per byte? Thanks, David
-----BEGIN PGP SIGNED MESSAGE----- In article <199601221851.NAA16938@amsterdam.lcs.mit.edu>, David Mazieres <dm@amsterdam.lcs.mit.edu> wrote:
The problem with RC4 is that it works in OFB only. If I need data integrity in the face of known plaintext, I will need to compute a MAC in paralell with the encryption which could significantly slow things down.
If you want authentication, you must use a crypto-strength MAC. Encryption (be it RC4, DES, etc.) is not enough.
With a block cypher in CFB, I can just re-encrypt the last block of data.
False. CFB has limited error propagation, so if I modify any block before the next-to-last, it will not show up with your method. This seems to be a really common error. If you want message integrity guarantees, you must use a MAC. Always. - --- [This message has been signed by an auto-signing service. A valid signature means only that it has been received at the address corresponding to the signature and forwarded.] -----BEGIN PGP SIGNATURE----- Version: 2.6.2 Comment: Gratis auto-signing service iQBFAwUBMQV+LioZzwIn1bdtAQF7pgGAm6GnmZqPSElx8mVyonD9BqScefdZLhul fv/qU/bsEDM2YyKuBpoFWyKMwIH0jyzx =Bp2Q -----END PGP SIGNATURE-----
participants (3)
-
David Mazieres -
daw＠beijing.CS.Berkeley.EDU -
James A. Donald