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Unformatted text preview: ntire year. For any given pair of people, the possibly of
them having the same birthday is 1/m = 1/365 ;
them Probability of zero collision
= Probability that all of the n people have different
= m * (m-1) * (m-2) *…* (m-n+1) / mn
= 1 – n(n-1)/2m approximately when m>>n
n(n-1)/2m Pcollision = 1 – Probability of zero collision
= n(n-1)/2m approximately
n(n-1)/2m How difficult to find a Hash collision ?
How secure is a one-way hash with 64-bit output ? Based on the property of a good hash function, the hash
output of any input string should be uniformly distributed over
the hash output space of size m=264
the This is analogous to the fact that the birthday of any given
person is uniformly distributed over any days within a year
(i.e. output space of size m = 365) Thus, according to the Birthday Paradox, if no. of all possible
outcomes = m, we only need to try about n = √ m inputs to
the hash function to have a good chance to f...
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This note was uploaded on 12/05/2013 for the course IERG 4130 taught by Professor Chowsze-ming,sherman during the Fall '13 term at CUHK.
- Fall '13