NIST established the Threshold Cryptography project to drive an effort to standardize threshold schemes for cryptographic primitives. Threshold schemes enable distribution of trust placed on human operators, and mitigate several single-points of failure in conventional cryptographic implementations.
Threshold schemes often rely on
secret-sharing schemes,
which
split a secret into parts, called shares.
Any “share” is unintelligible on its own, but
by combining several shares it is possible to recover the secret.
For example, Charlie can split a secret into two shares and send one to Alice and another to Bob.
Threshold schemes go beyond secret-sharing and enable crypto operations (such as signing, encrypting and decrypting) without ever reconstructing the key in any place.
Additional information: https://doi.org/10.6028/NIST.IR.8214A (Hint: this is just an informative slide ... you need to go somewhere else to find two shares and reconstruct a secret)
A simple example of Secret-Sharing
Reconstruct Charlie's 3-digit key from
the shares given to Alice and
Bob