How Shamir's Secret Sharing Works
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Re: How Shamir's Secret Sharing Works
#2[flagged]
Re: How Shamir's Secret Sharing Works
#3before I learned of shamir secret sharing, I wondered why one couldn't do the same exact thing with a par2 like system (albiet with smaller pieces than a par2 system would traditionally have). i.e. you have X bits of data, you create Y*X/N sized recovery blocks (where Y > N). You hand each recovery block to individual users. and any N users can get together to recover the key and decrypt the contents.
Re: How Shamir's Secret Sharing Works
#4if the secret is large usually it's encrypted and the payload is distributed along with the shares of the key.
but you can also just use Reed-Solomon and split the payload, the difference with Shamir is that you lose information-theoretic security (you lose it the moment you use encryption anyway) and the payload also needs to undergo an all-or-nothing-transform (AONT).
AONT transforms the entire payload into an encrypted blob which also serves as its own key, a withheld piece is a de facto encryption key. this is required because Reed-Solomon can have pathological cases where pieces leak information.
Re: How Shamir's Secret Sharing Works
#5before I learned of shamir secret sharing, I wondered why one couldn't do the same exact thing with a par2 like system (albiet with smaller pieces than a par2 system would traditionally have). i.e. you have X bits of data, you create Y*X/N sized recovery blocks (where Y > N). You hand each recovery block to individual users. and any N users can get together to recover the key and decrypt the contents.
[deleted]
Re: How Shamir's Secret Sharing Works
#6Here is Ente's implementation: (https://2of3.ente.com/)
Re: How Shamir's Secret Sharing Works
#7if the secret is large usually it's encrypted and the payload is distributed along with the shares of the key. but you can also just use Reed-Solomon and split the payload, the difference with Shamir is that you lose information-theoretic security (you lose it the moment you use encryption anyway) and the payload also needs to undergo an all-or-nothing-transform (AONT). AONT transforms the entire payload into an encr…
Reed-Solomon is an Erasure code, and I definitely wouldn't look to that for Secret Splitting. Those leakage models are gnarly. But if you want something else that is more general - there are Monotone Span Programs. Seriously underused.
Re: How Shamir's Secret Sharing Works
#8This is such a cool technique, and you could even teach it in secondary schools as a neat thing computer scientists can do with polynomials.
Re: How Shamir's Secret Sharing Works
#9if the secret is large usually it's encrypted and the payload is distributed along with the shares of the key. but you can also just use Reed-Solomon and split the payload, the difference with Shamir is that you lose information-theoretic security (you lose it the moment you use encryption anyway) and the payload also needs to undergo an all-or-nothing-transform (AONT). AONT transforms the entire payload into an encr…
Reed-Solomon is an Erasure code, and I definitely wouldn't look to that for Secret Splitting. Those leakage models are gnarly. But if you want something else that is more general - there are Monotone Span Programs. Seriously underused.
> Reed-Solomon is an Erasure code
> Those leakage models are gnarly.
Re: How Shamir's Secret Sharing Works
#10something tangentially i am interested in is computing following the 'two person rule' for things like sudo. Yes I am logged into server X at terinal Y, and so is my co-worker and we both sign off on running command X