Clear DefinitionsTiming Attack Analysis
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Pronunciation
[tahy-ming uh-tak uh-nal-uh-sis]
Analogy
Think of timing attack analysis like listening to the clicks of a lock to deduce its combination one number at a time.
Definition
The evaluation of software or hardware implementations to detect vulnerabilities that leak sensitive information through execution time variations.
Key Points Intro
Timing analysis uncovers side-channels that reveal secrets via timing differences.
Key Points
Constant-time coding: ensures operations take equal time regardless of inputs
Statistical testing: uses t-tests to detect significant timing variances
Microbenchmarking: profiles individual functions at nanosecond granularity
Mitigations: applies masking, blinding, and avoiding data-dependent branches
Example
An audit of an HMAC implementation measures comparison times to confirm no early-exit branches reveal partial matches.
Technical Deep Dive
Analysts instrument code paths with high-resolution timers, collect timing samples across varied inputs, apply statistical analysis (e.g., Welch’s t-test), and inspect assembly to identify data-dependent branches or memory access patterns. Countermeasures include lookup tables with uniform access and algorithmic blinding.
Security Warning
Unmitigated timing leaks can allow attackers to recover cryptographic keys or passwords.
Caveat
Achieving perfect constant-time behavior is challenging on complex CPU architectures and high-level runtimes.
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