Cryptography How many possible 256 bit semiprimes exist? |
- How many possible 256 bit semiprimes exist?
- Algorithm for creating Smart lock passwords
- [CODE] AES encryption primitives
- Why are 2 prime numbers used for RSA rather than just 2 odd numbers?
- Key generating and exchanging for simple AES encryption
| How many possible 256 bit semiprimes exist? Posted: 27 Feb 2019 12:24 PM PST Say we're generating a public RSA key of 256 bits, that is the modulus n. We know that n must be 256 bits long, and must be a semiprime. Are there really that many 256 bit semiprimes? I'm just a bit confused on what a 256-bit number really means -- I know that it's a number that takes 256 bits to represent. This implies that a 256 bit number is between 0 and (2256 )-1 correct? [link] [comments]  |
| Algorithm for creating Smart lock passwords Posted: 27 Feb 2019 02:58 PM PST Hey guys, I've got several apartments listed on AirBnB and Booking, but lately I've had hard time coordinating them on web, bringing keys to the guests and so on, so I'd come up to an idea of installing keypad locks and distributing those time dependent keys automatically to guests from the site when they make a reservation. All my smart locks would have wi fi connection on server, but with wi fi signal lost or loss of power my lock wouldn't be online anymore. For such accidents I've thought of creating offline mode where battery powered keypad would still recognize password. For that purpose I need somehow to seed in three information inside password : 1)check in time 2)check out time 3)lock ID Check in time doesn't have to be more precise than 15 minutes (which gives us 96 separate possibilities during one day, or around 35000 a year), Check out could be thought of as 'time after check in' (if maximum stay is lets say 30 days, that gives us ~3000 values). Lock ID identifies certain apartment. Since I don't want my password to be longer than 6 digits, that gives us a million different combinations. Obviously far less then possible combinations of needed info. So my question is : can you think of best algorithm that would provide enough security to open the door even when there is no connection ? Note: When everything is normal and lock is online, only correct password would be the one sent by the server. Only in non-connected mode, lock would analyze the key through that alghorithm and if a guest enters one that fits inside information (time, date, lockID) it gives them access On following links I provide some already existing offline unlock solutions for this problem (so it's doable :D ). [link] [comments]  |
| [CODE] AES encryption primitives Posted: 27 Feb 2019 06:34 PM PST |
| Why are 2 prime numbers used for RSA rather than just 2 odd numbers? Posted: 27 Feb 2019 01:43 PM PST https://en.wikipedia.org/wiki/RSA_(cryptosystem) I do not see how using 2 large odd numbers is any different than 2 prime numbers. Why is multiplying 2 prime numbers secure but multiplying 2 odd numbers not secure? What does having more factors do to ease decryption? From that Wikipedia page I do not see anywhere in the steps where knowing any factor aids in decryption. [link] [comments]  |
| Key generating and exchanging for simple AES encryption Posted: 27 Feb 2019 02:33 AM PST Hello everyone. I'm working on a project that implement a simple AES encryption with C++. My teacher required us to perform key generation and exchange in addition to algorithm demo. Can anyone suggest a way to do it? I'm sorry if my question is too straightforward as I'm a totally newbie in this subject. Any help is appreciated. [link] [comments]  |
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