Shamir's Secret Sharing

Shamir's Secret Sharing is an algorithm created by Adi Shamir (an Israeli cryptographer) to break something into parts that can be reconstituted if at least some certain number of the parts (which might be less than all of them) are brought back together. It can be used for sharing a secret key in a way that requires multiple recipients to get together in order to do the decryption. Horcrux (jesseduffield) uses this algorithm for key splitting.

Links

 * Wikipedia article
 * How to share a secret (ACM paper, paywalled)
 * GNU implementation