"With 64-bit sessions, the odds of having two people have the same session is 1 in approximately 18446744073709551616." Please read about the Birthday Paradox:

"With 64-bit sessions, the odds of having two people have the same session is 1 in approximately 18446744073709551616." Please read about the Birthday Paradox: http://en.wikipedia.org/wiki/Birthday_Paradox http://en.wikipedia.org/wiki/Birthday_Paradox . The probably of a random collision in 64 bits is 1 in 2^32, not 1 in 264.