4 ms·
Sharing secrets and distributing passwords
- dexter313 14y agoIt explains how a password can be cut up in pieces and distributed so that each piece individualy can be used to reveal the secret. Skip to >>Shamir’s Algorithm<< section to get to the most interesting part.
- cypherpunks01 14y agoThe ssss unix utility does this, it's fun to use. Docs at http://point-at-infinity.org/ssss/ http://point-at-infinity.org/ssss/, demo at http://point-at-infinity.org/ssss/demo.html http://point-at-infinity.org/ssss/demo.html and it can be installed on ubuntu through the 'ssss' package, listed as ssss - Shamir's secret sharing scheme implementation.
- ryan-c 14y agoHere's one I wrote that wraps the algorithm with passwords https://github.com/ryancdotorg/threshcrypt https://github.com/ryancdotorg/threshcrypt and you can set the same password multiple times to accomplish the second 'advanced scenario'.
- xk_id 14y agohmm.. the article says: "If we encoded our secret with a cubic function and distributed coordinate sub-passwords it would require any combination of four points to determine the intercept and the secret." Maybe I'm missing something here, but, taking any of the cubic function diagrams as example, what if all four coordinates have their "x" between -10 and 0? Those four coordinates will not be enough to generate the whole curve, no?
- lucas-beyer 14y agoNo. As soon as you have 4 points, these 4 points uniquely define a cubic. Even if those 4 points are "right next" to eachother. If this is difficult to imagine, it is the same with a line. Wherever you place 2 points, they always uniquely define a single line. Unless, of course, you place 2 points exactly on top of eachother.
- xk_id 14y agoreally? that's amazing! I'd love to see a formal proof of this. edit: I suppose this counts as proof http://www.had2know.com/academics/cubic-through-4-points.html http://www.had2know.com/academics/cubic-through-4-points.htm..., but atm I don't remember why matrixes are connected with equations.
- joshzayin 14y agoThere's a more general proof at https://docs.google.com/viewer?a=v&q=cache:euFgQLUCTfwJ:nm.mathforcollege.com/mws/gen/05inp/mws_gen_inp_bck_introduction.pdf+&hl=en&gl=us&pid=bl&srcid=ADGEESg6HcId-jvRg7Ihh3dMF3DGTmBUCUOukBjCH1SunBJxGZFV3gri-zWyN91qUSinDMFJ3lvexKfgAvN3xewN2mWfG6idDKfHutuAcb62pH-UHJJXLUnbo3dCjt12NyTTYiZHuqDR&sig=AHIEtbSO9AURkaDNywKJ62dsSWklsecAEw https://docs.google.com/viewer?a=v&q=cache:euFgQLUCTfwJ:... that looks reasonable at a skim.
- xk_id 14y agoAwesome!
- cprussin 14y agohttps://en.wikipedia.org/wiki/Threshold_cryptosystem https://en.wikipedia.org/wiki/Threshold_cryptosystem
- snprbob86 14y agoThis is an extremely interesting and well written article. More like this please!