An administrator is testing the collision resistance of different hashing algorithms.
Which of the following is the strongest collision resistance test?
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A. B. C. D.A.
The correct answer is A. Find two identical messages with different hashes.
Hashing algorithms are used to convert data of any size into a fixed size output. Hashes are used in many applications such as digital signatures, password storage, and message authentication. A hash function is considered to be collision-resistant if it is very difficult to find two inputs that produce the same hash output.
The strongest test for collision resistance is to find two identical messages with different hashes. This test is also known as a "birthday attack." The birthday attack is based on the probability that in a group of n people, there is a 50% chance that two people will have the same birthday when n is 23.
Similarly, in hashing, if there are n possible outputs, there is a 50% chance that two inputs will have the same output when the number of inputs is approximately the square root of n. Therefore, to test the collision resistance of a hashing algorithm, an attacker would attempt to find two inputs that produce the same hash output.
Option B, finding two identical messages with the same hash, is not a strong collision resistance test because it is relatively easy to find two identical messages with the same hash output. Option C, finding a common hash between two specific messages, and option D, finding a common hash between a specific message and a random message, are also weak tests because they do not test the strength of the hashing algorithm in finding collisions.