4 ms·
Birthday paradox.
by blumentopf 10y ago
Birthday paradox.
- Ar-Curunir 10y agoLol the chances of a collision are still too low.
- moyix 10y agoSuppose the ace02468bdf13579 is a random hex string. That's 8 bytes of data, or 1/2^64 to get that specific value. With the birthday paradox, that only gets you down to 1/2^32 or one in 4 billion chance. Not happening.
- pklausler 10y agoWhile that 64-bit value would be just as likely to occur as any other if randomly chosen, any competent programmer is going to recognize a very strong pattern in that value's binary representation that makes it much more likely to have been chosen with intent. In fact, the pattern is so strong, there's a chance that the appearances of the value in two places is simply a coincidence.
- pklausler 10y agoSpecifically, in C, it's (0x01234567uLL + 0x55555555 & 0x77777777) * 0x200000002 + 0x11111111
- acqq 10y agoYes, googling for the 32-bit parts of that 64-bit hex value gets me two distinct hits: 2015: http://www.ijirst.org/articles/IJIRSTV1I9059.pdf http://www.ijirst.org/articles/IJIRSTV1I9059.pdf and 2013: https://www.halowaypoint.com/en-us/forums/d76f090378914a9bb85312f87cf09b99/topics/classified-section-3-decoding-center/ac50b7bf-5abc-4043-bc7f-772fd764047b/posts?page=11 https://www.halowaypoint.com/en-us/forums/d76f090378914a9bb8... Still, the string (instead of the binary values) is somewhat less probable than this to be an accidental match.
- ttctciyf 10y agoWell, if the string was a widely occuring one (say, because it's useful in some coding task, etc.) you might expect it to turn up a few times in a google search for occurrences prior to Aug 1 2016. But, apparently not: https://www.google.com/search?q=ace02468bdf13579&client=firefox-b&source=lnt&tbs=cdr%3A1%2Ccd_min%3A%2Ccd_max%3A8%2F1%2F2016&tbm= https://www.google.com/search?q=ace02468bdf13579&client=fire...