Timeline for Can future Bitcoin hashes be considered a good source to generate random numbers?
Current License: CC BY-SA 4.0
23 events
| when toggle format | what | by | license | comment | |
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| Sep 6, 2019 at 21:44 | vote | accept | Serginho | ||
| Jul 31, 2019 at 13:45 | answer | added | István András Seres | timeline score: 5 | |
| S Jul 2, 2019 at 16:01 | history | bounty ended | CommunityBot | ||
| S Jul 2, 2019 at 16:01 | history | notice removed | CommunityBot | ||
| Jun 26, 2019 at 7:13 | comment | added | forest | @camp0 Those hash functions do not add any entropy. If you feed a hash function with a string with a certain amount of entropy, the resulting digest will have no more, and possibly less. | |
| Jun 25, 2019 at 21:16 | history | edited | Serginho | CC BY-SA 4.0 |
added 274 characters in body
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| Jun 25, 2019 at 21:08 | comment | added | Paul Uszak | Ah! You might want to then edit the question with this. Otherwise the detail gets lost in all the chit chat... | |
| Jun 25, 2019 at 21:04 | comment | added | Serginho | @PaulUszak For example, use the bitcoin hash as a entropy or seed to generate random numbers. How would you solve this problem? What algorithm would you use to generate random numbers with the bitcoin hash as a input seed? but the algorithm should be secure and have a good entropy | |
| Jun 25, 2019 at 9:00 | history | tweeted | twitter.com/StackCrypto/status/1143443851568435200 | ||
| S Jun 25, 2019 at 4:13 | history | suggested | Patriot | CC BY-SA 4.0 |
minor mistakes; verbal agreement
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| Jun 25, 2019 at 1:20 | review | Suggested edits | |||
| S Jun 25, 2019 at 4:13 | |||||
| Jun 24, 2019 at 22:52 | comment | added | Paul Uszak | Answers might be more forthcoming if you expand the question slightly. One sentence is a little short to explain what you mean by "generated hashes have a good randomness?" | |
| Jun 24, 2019 at 15:22 | comment | added | camp0 | In general the SHA256, BLAKE, SHA-3 , etc.. have good entropy so you can consider if you want that are random if you generate a file with them, you will see that the dispersion of the bytes is homogeneus. | |
| S Jun 24, 2019 at 14:12 | history | bounty started | Serginho | ||
| S Jun 24, 2019 at 14:12 | history | notice added | Serginho | Draw attention | |
| Jun 23, 2019 at 3:15 | comment | added | forest | @JonHutton Hex is just a representation of a hash output. The output itself is binary. | |
| Jun 23, 2019 at 0:03 | comment | added | Jon Hutton | What method would you use to take a 256 hex char table into something usable as a rng. Wouldn't you have to transform it to binary to make it usable? | |
| Jun 22, 2019 at 15:53 | comment | added | Future Security | (Using a counter is actually slightly cheaper and faster than using a new random number every time. Again, with no negative side effects. Real mining hardware might use some other form of "counting", eg. using a hardware LFSR, to save a little more energy. This is also very theoretical. Someone succeeding in biasing results has to win the mining race, which probably wouldn't be likely or worth the expense. At least while bitcoin is popular.) | |
| Jun 22, 2019 at 15:40 | comment | added | Future Security |
I've not looked into details of mining hardware and this is over-simplified, but I've read that miners basically pick a random r to start with; then each subsequent hash uses ++r. Everyone can use this one strategy without miners repeating work that's already failed for someone else. If you ignore the fact that a miner might not have hardware that's designed for this, the initial r can be rounded to a multiple of 5 and ++r can be replaced with r += 5. That wouldn't effect the probability of success or required number of hashes. Nor does it have the redundant mining issue.
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| Jun 22, 2019 at 11:48 | comment | added | Serginho | @FutureSecurity I suppose each miner use a different strategy to get the right hash, otherwise everyone would be calculating the same hashes and it would always win the fastest. So if we have a group of people that uses strategies and another group that uses random strings (I pretty sure this group exists, specially if you can't rival with the most powerful), we can consider the next hash is completely random and unpredictable. | |
| Jun 22, 2019 at 0:46 | comment | added | Future Security | They don't have to try random strings. Any input is as likely as every other input to create a SHA-256 output with a desired prefix. A miner can try to win Bitcoin's high-carbon-footprint lottery using only inputs that were a multiple of 5, for example, or only inputs that end with the ASCII bytes for the string "cat". They would find a winning input in the same expected number of tries, even though they aren't using random inputs, because SHA-2 behaves somewhat like a random oracle. So they could bias the result and succeed with a probability equal to them first winning the Bitcoin race. | |
| Jun 21, 2019 at 15:50 | review | First posts | |||
| Jun 22, 2019 at 15:39 | |||||
| Jun 21, 2019 at 15:46 | history | asked | Serginho | CC BY-SA 4.0 |