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Re: TLS vs. IPsec (Was: Re: experiments in the ietf week)

2008-03-26 07:37:43
At Wed, 26 Mar 2008 07:32:41 -0700,
Eric Rescorla wrote:

At Wed, 26 Mar 2008 15:01:21 +0100,
Iljitsch van Beijnum wrote:

On 26 mrt 2008, at 14:36, Eric Rescorla wrote:

- Modern cryptographic implementations are extremely fast. For
 comparison the MacBook Air I'm typing this on will do order 10^6
 HMAC-MD5s/second on 64-byte packets.  So, to consume all my
 resources would require order 10^8 bits per second, which is a
 pretty serious packet-based DoS ittack on many contexts.

This is a bogus argument. Implementations are always inferior to  
optimistic performance claims 

What do you mean "optimistic performance claims"? I ran
"openssl speed". That's actually a pretty good reflection
of what the performance of SSL implementation will be.

That said, there is a dependency on cipher suite. So, RC4-MD5
is not too much slower than HMAC-MD5 alone. By contrast, 
AES-SHA1 is maybe 4x slower. OTOH, I only was counting the 
size of the TLS records themselves, so when you add the TCP
and UDP headers, the bit rate is probably twice as high.

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