Birthday Attack Calculator
Calculate birthday attack parameters, collision probability, time to collision, and attack feasibility for hash functions.
Inputs
bits
Results
Birthday Bound
400,651,869,298,001,200,000,000,000,000,000,000,000
50% Probability Bound
400,651,869,298,001,200,000,000,000,000,000,000,000
Time to Collision
0 years
Storage Required11,940,356,174,051,796,000,000,000,000,000 GB
Estimated Cost$4,006,518,692,980,011,700,000,000,000,000.00
How to Use This Calculator
- Enter the hash function output size in bits.
- Set the number of hashes the attacker can compute per second.
- Review the number of hash computations needed for a 50% collision probability.
- Verify that your hash function output size is at least 2x the desired security level in bits.
- For 128-bit security, use SHA-256 or stronger -- MD5 and SHA-1 are vulnerable.
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Formula
Birthday Bound ≈ √(2 × m × ln(1/(1-P)))Related Calculators
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