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What is timing attacks in PHP?
In cryptography, a timing attack is a side-channel attack in which the attacker attempts to compromise a cryptosystem by analyzing the time taken to execute cryptographic algorithms. Information can leak from a system through measurement of the time it takes to respond to certain queries.
What is the aim of chosen-ciphertext security?
During the chosen-ciphertext attack, a cryptanalyst can analyse any chosen ciphertexts together with their corresponding plaintexts. His goal is to acquire a secret key or to get as many information about the attacked system as possible.
What is chosen-ciphertext security?
A chosen-ciphertext attack (CCA) is an attack model for cryptanalysis where the cryptanalyst can gather information by obtaining the decryptions of chosen ciphertexts. From these pieces of information the adversary can attempt to recover the hidden secret key used for decryption.
How does a timing attack work in PHP?
Timing attacks against string comparisons are not PHP-specific. They work in any context where a user-provided string is checked against a secret string using the standard “short circuit” comparison algorithm (the check stops on the first non-matching byte).
Can a timing attack be used on a computer?
Every logical operation in a computer takes time to execute, and the time can differ based on the input; with precise measurements of the time for each operation, an attacker can work backwards to the input. Finding secrets through timing information may be significantly easier than using cryptanalysis of known plaintext, ciphertext pairs.
Which is the most powerful example of a timing attack?
The 2017 Meltdown and Spectre attacks which forced CPU manufacturers (including Intel, AMD, ARM, and IBM) to redesign their CPUs both rely on timing attacks. As of early 2018, almost every computer system in the world is affected by Spectre, making it the most powerful example of a timing attack in history.
Why is it difficult to remove timing dependencies?
Removing timing-dependencies is difficult in some algorithms that use low-level operations that frequently exhibit varied execution time. Timing attacks are often overlooked in the design phase because they are so dependent on the implementation and can be introduced unintentionally with compiler optimizations.