Cryptography & Security
Advanced
Birthday Bound
Collisions become likely after about √ of the hash space.
Formula
Variables
nItems for 50% collision
bHash size (bits)
Example
64-bit hash: n ≈ 5×10⁹ before a collision is likely
Did You Know?
The birthday paradox is why a 256-bit hash gives only 128 bits of collision resistance.
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