grempe / secretsharing

NO LONGER MAINTAINED, please see important news in README.md. Shamir's Secret Sharing is an algorithm in cryptography. It is a form of secret sharing, where a secret is divided into parts, giving each participant its own unique part, where some of the parts or all of them are needed in order to reconstruct the secret. Holders of a share gain no knowledge of the larger secret.

Hi there, I'm Glenn - aka @grempe 👋

I'm a Husband, Father, Developer, and the Founder & CEO of Truestamp (on GitHub @truestamp)!!

• 🌱 I’m currently growing Truestamp 🤣
• 👯 I’m focused on the intersection of Privacy, Security, Cryptography, and Integrity
• 🥅 Goals: Help my customers verify the integrity of their most important data
• ⚡ Fun fact: My vehicle license plate has a cryptography reference. I think it confuses most who see it

Connect with me

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• Twitter @grempe or @truestamp
• Mastodon @[email protected]
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GitHub Stats

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secretsharing's Issues

Published to Rubygems.

I'm very impressed with this implementation and looking forward to using it my own project. I notice that you have contributed some great code clean up to the originally published gem.

Will these changes be contributed back to a new version of the published 'secretsharing' gem or will they remain on your fork? I'm just trying to figure out the best way to get your latest code into my project.

Thanks!
Andy

Design Review - Abstract out Cryptographic Primatives

This is refactoring idea I've been kicking around. I would be happy to
implement this if I could get your thoughts before I take the plunge.

Right now the implementation is coupled tightly with OpenSSL. This this makes
sense for most users but it does not seem to be a core concern of the
SSS Algorithm.

Specifically, I do not us OpenSSL in my project, I use DJB's NaCl. Also, maintaining
tight control over my Random Number generator, is very important to me.

I'm wondering if we can abstract away some of these more primative functions.
Something like:

module SecretSharing
  class BigNumber
    # call OpenSSL::BN from One Place
  end
end

module SecretSharing
  class RandomNumber
    # call OpenSSL Random Number Generations from One Place
  end
end

This would allow us to depend on abstraction and provide the opportunity to swap out crypto libraries, leaving OpenSSL as the smart default.

Failing to retrieve secret with some combination of 3 out of 5

This combination fails

[27] pry(main)> secret='100057108055106048110037051094112064114038050069035073097053043122033082121074107056090102067'
=> "100057108055106048110037051094112064114038050069035073097053043122033082121074107056090102067"
[28] pry(main)> s=SecretSharing::Shamir.new(5,3)
=> #<SecretSharing::Shamir:0x0000000771f820
 @k=3,
 @n=5,
 @received_shares=[],
 @secret=nil,
 @shares=[]>
[29] pry(main)> s.set_fixed_secret(secret)
=> #<OpenSSL::BN:0x0000000784c810>
[30] pry(main)> shares=s.shares.map(&:to_s)
=> ["001FF69184824D423CC4BA75B320143BB541358BC03C0DF81BC899DF25F267E3B334304E7DD81807DB5A4D",
 "00279F04A8FE67F4331423AE9B867529800816314A1B77ED518F1390073495648F2FE98411547D3E6B8A4D",
 "003A0B40BA0C9D4FCD6AF67D7D8827460B297031517EC08C011997F1EAA843EFF9CA0A88CA92EB6DAB614D",
 "004173B45B7ACED550BC932E259252A9156A5438BD665E7D42A682704D04D7385F302935CA9936294607E4D",
 "005F2F13A1DF5803EE2ED8DD2E5D7F0B627B9040D8D0EDC5CD7AC0C8B82424267AD983FFAE55E01E06BF4D"]
[31] pry(main)> r=SecretSharing::Shamir.new(3)
=> #<SecretSharing::Shamir:0x000000078f4880
 @k=3,
 @n=3,
 @received_shares=[],
 @secret=nil,
 @shares=[]>
[32] pry(main)> r<<shares[0]
=> false
[33] pry(main)> r<<shares[1]
=> false
[34] pry(main)> r<<shares[4]
OpenSSL::BNError: no inverse
from /home/assaf/.rvm/gems/ruby-2.0.0-p353/gems/secretsharing-0.3/lib/secretsharing/shamir.rb:225:in `mod_inverse'
[35] pry(main)> 

This combination succeeds

[36] pry(main)> r2=SecretSharing::Shamir.new(3)
=> #<SecretSharing::Shamir:0x00000006119dc8
 @k=3,
 @n=3,
 @received_shares=[],
 @secret=nil,
 @shares=[]>
[37] pry(main)> r2<<shares[2]
=> false
[38] pry(main)> r2<<shares[1]
=> false
[39] pry(main)> r2<<shares[0]
=> true
[40] pry(main)> r2.secret.to_s
=> "100057108055106048110037051094112064114038050069035073097053043122033082121074107056090102067"
[41] pry(main)>