Re: [TLS] SSL Renegotiation DOS
Martin Rex <mrex@sap.com> Tue, 15 March 2011 16:06 UTC
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From: Martin Rex <mrex@sap.com>
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To: jorge@orchilles.com
Date: Tue, 15 Mar 2011 17:07:42 +0100
In-Reply-To: <AANLkTin2i3+K8oV68pZFJ0xabjEugJLePyZTTaZSr0VE@mail.gmail.com> from "Jorge A. Orchilles" at Mar 15, 11 08:31:28 am
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Cc: tls@ietf.org
Subject: Re: [TLS] SSL Renegotiation DOS
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Jorge A. Orchilles wrote: > > Marsh Ray has invited me to present my research and report on SSL/TLS > Renegotiation Denial of Service on this mailing list. I have posted this on > my site and will paste here for your feedback: > http://orchilles.com/2011/03/ssl-renegotiation-dos.html > > *SSL/TLS Renegotiation Denial of Service* > > An SSL/TLS handshake requires at least 10 times more processing power on the > server than on the client. I'm sorry, I completely fail to see what renegotiation has to do with the DoS capability here. The TLS protocol is a cryptographic protocol, and servers that expect to talk to real clients performing the protocol as designed will attempt to perform the cryptographic operations as requested. A DoS-client could simply open new connections to the SSL server and blindly fire away precompiled static SSL handshake messages, forcing the server to do crypto work. You should be able to make most servers perform RSA decrypts on arbitrary data, and a significant number to perform DHE computations. -Martin
- Re: [TLS] SSL Renegotiation DOS Jorge A. Orchilles
- [TLS] SSL Renegotiation DOS Jorge A. Orchilles
- Re: [TLS] SSL Renegotiation DOS Nikos Mavrogiannopoulos
- Re: [TLS] SSL Renegotiation DOS Steve Dispensa
- Re: [TLS] SSL Renegotiation DOS Joe Orton
- Re: [TLS] SSL Renegotiation DOS Dr Stephen Henson
- Re: [TLS] SSL Renegotiation DOS Steve Dispensa
- Re: [TLS] SSL Renegotiation DOS Martin Rex
- Re: [TLS] SSL Renegotiation DOS Eric Rescorla
- Re: [TLS] SSL Renegotiation DOS Marsh Ray
- Re: [TLS] SSL Renegotiation DOS Martin Rex
- Re: [TLS] SSL Renegotiation DOS Steve Dispensa
- Re: [TLS] SSL Renegotiation DOS Peter Gutmann
- Re: [TLS] SSL Renegotiation DOS Martin Rex
- Re: [TLS] SSL Renegotiation DOS Peter Gutmann
- Re: [TLS] SSL Renegotiation DOS Jorge A. Orchilles
- Re: [TLS] SSL Renegotiation DOS Jorge A. Orchilles
- Re: [TLS] SSL Renegotiation DOS Jorge A. Orchilles
- Re: [TLS] SSL Renegotiation DOS Jorge A. Orchilles
- Re: [TLS] SSL Renegotiation DOS Jorge A. Orchilles