3 ms·

Duplicate hashes are an issue because of the birthday problem: http://en.wikipedia.org/wiki/Birthday_problem http://en.wikipedia.org/wiki/Birthday_problem The

• gibybo 14y ago
  No, it's still not an issue. Check out the table for 256 bit numbers in the article you linked. To get a 0.1% probability of even a single collision, you need to generate 1.5e37 hashes. At 10 TH/s, that would take 3e17 years. 10 million times longer than the age of the universe.
• mikeash 14y ago
  The birthday paradox basically says that you can expect a collision when you've explored the square root of the problem space. For birthdays, you expect a collision in a group of sqrt(365) ~= 19 people. For a 256-bit hash, you expec a collision in a group of 2^128 hashes. That is still huge. Absent a weakness in the hash being found, it's unlikely anyone will ever generate two colliding hashes.