Re: [TLS] Safe ECC usage

Johannes Merkle <johannes.merkle@secunet.com> Tue, 01 October 2013 16:23 UTC

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Date: Tue, 01 Oct 2013 18:22:07 +0200
From: Johannes Merkle <johannes.merkle@secunet.com>
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Cc: "tls@ietf.org" <tls@ietf.org>, Kyle Hamilton <aerowolf@gmail.com>
Subject: Re: [TLS] Safe ECC usage
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>> Other than certificate size and the speed of making those calculations?
>> Really, try "openssl speed rsa2048 ecdsap256" on any Linux or Mac machine.
> 
> openssl 1.0.1c x86_64 tells me ecdsap256 is 10x faster than rsa2048 for
> signing and 10x slower than rsa2048 for verifying.

RSA is much faster for signing than for verifying, while for ECDSA the time for these operations are quite similar.

So lets assume, ECDSA singing or verifying takes 1/10 s, then RSA signing takes 1 s and verifying 1/100 sec. Makes 0.2 s
for ECDSA based handshake (one signing and one verifying operation) and 1.01 s for RSA. That is a huge difference.

Johannes