Re:Google disables compression for OpenSSL in Chrome - SSL e...
by mindslight on Wednesday September 12, 2012 @01:36PM
(#4511801)
It's not so much that the data itself is in motion, but that online secrecy/authentication necessarily implies widely-available encryption/verification oracles. Oracles with possible implementation vulnerabilities (/features) that can be abused to answer questions such as "What's the encrypted encoding of the secret++X" or "How long does it take to check if X is valid" ?
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Re:Google disables compression for OpenSSL in Chrome - SSL e...
by tptacek on Wednesday September 12, 2012 @01:49PM
(#4511889)
Data in motion creates opportunities for adaptive chosen plaintext attacks that aren't present in data-at-rest scenarios. An "oracle" is a basic characteristic of a cryptosystem, not a flaw, but the "oracle attacks" you're thinking of are instances of adaptive attacks.
Re:Google disables compression for OpenSSL in Chrome - SSL e...
by mindslight on Wednesday September 12, 2012 @02:31PM
(#4512200)
But it's not the fact that the data is being transported that's leading to new attacks, it's that the parties are online and responding to arbitrary messages sent by the attacker. The data itself isn't creating problems - what's new is the ability for the attacker to ask interactive questions of the parties.
When authenticating messages, a receiver necessarily gains the ability to reject a message as invalid. Adaptive chosen plaintext attacks arise when this rejection ends up containing more information than a simple Y/N. From the perspective of an attacker, the verifier becomes an oracle capable of answering say "How many bytes are valid", leading to a sub-brute-force attack.