How to Share a Secret In this paper we show how to divide data D into n pieces in such a way that D is easily reconstructable from any k pieces, but even complete knowledge of k - 1 pieces reveals olutely no information about D. This technique enables the construction of robust key management schemes for cryptographic systems that can function securely and reliably even when misfortunes destroy half the pieces and security breaches expose all but one of the remaining pieces. CACM November, 1979 Shamir, A. Cryptography, key management, interpolation 5.39 5.6 CA791105 DB January 23, 1980 11:48 AM 3038 4 3177 3111 4 3177 3177 4 3177 3021 5 3177 3177 5 3177 3177 5 3177 3177 5 3177