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What is the difference between weak and strong collision resistance?
Even though they seem similar, there is a subtle difference between strong and weak collision resistance. Weak collision resistance is bound to a particular input, whereas strong collision resistance applies to any two arbitrary inputs.
What do you mean by birthday attack?
From Wikipedia, the free encyclopedia. A birthday attack is a type of cryptographic attack that exploits the mathematics behind the birthday problem in probability theory. This attack can be used to abuse communication between two or more parties.
What is the birthday paradox in cryptography?
In probability theory, the birthday paradox or birthday problem considers the probability that some paired people in a set of n randomly chosen of them, will have the same birthday.
What is a weak collision resistance?
Weak collision resistance (CR), or second-preimage resistance, is the property that given x and h(x) (h a hash function) it’s difficult to find x′≠x such that h(x′)=h(x). Strong CR, or just collision resistance, is the property that it’s difficult to find any two x,x′ with the same hash value.
What is weak collision resistant?
Collision resistance is a security notion of cryptographic hash functions. A collision of a hash function is a pair of different inputs which give the same output. In the new definition, weak collision resistance means that the probability of failing to find a collision is not negligible.
Which of the following algorithm is vulnerable to birthday attacks?
S1- MD5 is vulnerable to the Birthday attack.
What is the difference between strong and weak collision resistance?
Weak collision resistance (CR), or second-preimage resistance, is the property that given x and h ( x) ( h a hash function) it’s difficult to find x ′ ≠ x such that h ( x ′) = h ( x) . Strong CR, or just collision resistance, is the property that it’s difficult to find any two x, x ′ with the same hash value.
Which is a weak or strong collision vulnerability?
Strong collision vulnerability: It is “computationally feasible” for an attacker Mallory to find a free collision — to find any two messages x1 and x2 such that h (x1) == h (x2). The “XOR checksum” (and each non-cryptographic hashe in general) is weak collision vulnerable — and therefore is strong collision vulnerable.
Which is easier a hash function or a collision function?
The latter is easier than the former; the former is the “hash function analogue” of “same birthday as me” and the latter the analogue of “any two persons sharing a birthday”. Now then, what would a collision attack look like?
Is there a H that is not strongly collision resistant?
A similar argument would say that any h that is not weakly collision resistant is strongly collision resistant. But it’s absurd that the negations of the two concepts are the same! Where have I gone wrong? I prefer using definitions that explicitly specify who does what.