Physically Observable Cryptography

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In fact, physically observable cryptography may properly focus the research … Physically observable cryptography is a new and fascinating …

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Content
Physically Observable Cryptography
Silvio Micali. Leonid Reyzin?
November 29, 2003
Abstract
Complexity-theoretic cryptography considers only abstract notions of computation, and
hence cannot protect against attacks that exploit the information leakage (via electromagnetic
fields, power consumption, etc.) inherent in the physical execution of any cryptographic
algorithm. Such “physical observation attacks” bypass the impressive barrier of mathematical
security erected so far, and successfully break mathematically impregnable systems. The
great practicality and the inherent availability of physical attacks threaten the very relevance
of complexity-theoretic security.
To respond to the present crisis, we put forward physically observable cryptography: a powerful,
comprehensive, and precise model for defining and delivering cryptographic security against
an adversary that has access to information leaked from the physical execution of cryptographic
algorithms.
Our general model allows for a variety of adversaries. In this paper, however, we focus on
the strongest possible adversary, so as to capture what is cryptographically possible in the worst
possible, physically observable setting. In particular, we
?consider an adversary that has full (and indeed adaptive) access to any leaked information;
?show that some of the basic theorems and intuitions of traditional cryptography no longer
hold in a physically observable…