Clear DefinitionsKey Sharding
1 min read
Pronunciation
[kee shahr-ding]
Analogy
Key sharding is like cutting a treasure map into pieces—only by assembling enough pieces can you find the treasure.
Definition
Splitting a private key into multiple shares using secret sharing (e.g., Shamir’s) so that only a threshold of shares can reconstruct the key.
Key Points Intro
Key sharding secures keys via:
Key Points
Shamir’s Secret Sharing: n shares, threshold k.
Distributed storage: Shares held by distinct parties.
Threshold reconstruction: k shares needed to rebuild key.
Resilience: Tolerates loss of some shares.
Example
A 2-of-3 key sharding splits a private key into 3 shares; any 2 shares reconstruct the key for signing.
Technical Deep Dive
Using polynomial interpolation over a finite field: generate random degree k-1 polynomial with constant term = key. Evaluate at n points to produce shares. Reconstruction uses Lagrange interpolation on k shares.
Security Warning
Shares must be stored securely; share leakage reduces threshold security.
Caveat
Managing share distribution and backup increases operational complexity.
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