GHZ-Based Quantum Secret Sharing
Category: cryptography | Difficulty: intermediate | Qubits: 3 | Gates: 8 | Depth: 6
Quantum secret sharing uses a GHZ state to distribute a secret among N parties such that all parties must cooperate to reconstruct it. Alice encodes her secret (a random phase) into the GHZ state. Bob and Charlie each hold one qubit; neither can recover the secret without the other's measurement result. Security is guaranteed by quantum no-cloning and entanglement monogamy.
Expected Output
Measurement parity: c[0] XOR c[1] XOR c[2] = 0 (GHZ correlation)
Circuit
The OpenQASM 2.0 circuit is in circuit.qasm.
OPENQASM 2.0;
include "qelib1.inc";
// GHZ-based 3-party quantum secret sharing
// q[0]: Alice, q[1]: Bob, q[2]: Charlie
qreg q[3];
creg c[3];
// Create GHZ resource state
h q[0];
cx q[0],q[1];
cx q[0],q[2];
// Alice encodes secret (phase rotation pi/4 as example)
rz(0.7853981633974483) q[0];
// All parties measure in X basis to check correlations
h q[0]; h q[1]; h q[2];
measure q[0] -> c[0];
measure q[1] -> c[1];
measure q[2] -> c[2];
Tags
secret-sharing ghz-state cryptography multipartite
References
License
MIT -- part of the OpenQC Algorithm Catalog.