Shamir’s Secret Sharing

[radumarias]

Using Shamir's secret sharing, build a group encrypted folder with a minimum number of members available to access the files. This is good for shared folders where you want to increase security so that if one part of the key is compromised, it doesn't compromise the whole key, hence all the data.

Ref

• https://www.linkedin.com/pulse/building-threshold-cryptography-library-inrust-luis-soares-m-sc--hljxf/

The disadvantage is that each user can reconstruct the whole key and decrypt anything. See a solution that addresses this.

Structure notes

• Create a dedicated crate for this that uses rencfs (the core) as a lib. You can create attractions and common minimalistic generic functionality in the core but keep the core more generic

[radumarias]

• the alternative is the public key, because the single point of failure is that we need to reconstruct the key on one node
• also use zero sharing
• we could have each user have a key, and each chunk is encrypted with a different key, and on decrypt, we ask each user to decrypt sending content via TLS

[MarcIlunga]

I just wanted to add clarifications: The recommendation above is to avoid zero-sharing issues, both upon share construction and key reconstruction. See our writeup for more info on the issue.

[radumarias]

@MarcIlunga thank you, will investigate that