Create quantum_cryptography.py

quantum/algorithms/quantum_cryptography.py

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+# quantum_cryptography.py
+import numpy as np
+from qiskit import QuantumCircuit, Aer, transpile, assemble, execute
+from qiskit.visualization import plot_histogram
+from qiskit.quantum_info import Statevector
+
+class QuantumDigitalSignature:
+    def __init__(self, message):
+        """
+        Initialize the Quantum Digital Signature protocol.
+
+        Parameters:
+        - message: The message to be signed.
+        """
+        self.message = message
+        self.key = None
+
+    def generate_key(self):
+        """Generate a random key for signing."""
+        self.key = np.random.randint(0, 2, len(self.message))
+
+    def sign(self):
+        """
+        Sign the message using the generated key.
+
+        Returns:
+        - signed_message: The signed message as a quantum state.
+        """
+        if self.key is None:
+            raise ValueError("Key not generated. Call generate_key() first.")
+
+        # Create a quantum circuit for signing
+        circuit = QuantumCircuit(len(self.message))
+
+        # Encode the message and key into the quantum state
+        for i in range(len(self.message)):
+            if self.message[i] == '1':
+                circuit.x(i)  # Apply X gate for '1' bits
+
+            if self.key[i] == 1:
+                circuit.h(i)  # Apply Hadamard gate for key bits
+
+        # Measure the signed message
+        circuit.measure_all()
+
+        # Execute the circuit
+        backend = Aer.get_backend('qasm_simulator')
+        transpiled_circuit = transpile(circuit, backend)
+        qobj = assemble(transpiled_circuit)
+        result = execute(qobj, backend, shots=1024).result()
+        counts = result.get_counts()
+
+        return counts
+
+class QuantumSecretSharing:
+    def __init__(self, secret, n_shares):
+        """
+        Initialize the Quantum Secret Sharing protocol.
+
+        Parameters:
+        - secret: The secret to be shared (binary string).
+        - n_shares: Number of shares to create.
+        """
+        self.secret = secret
+        self.n_shares = n_shares
+
+    def share_secret(self):
+        """
+        Share the secret among n participants.
+
+        Returns:
+        - shares: List of shares for each participant.
+        """
+        # Create a quantum circuit for sharing the secret
+        circuit = QuantumCircuit(len(self.secret) + self.n_shares)
+
+        # Encode the secret into the quantum state
+        for i in range(len(self.secret)):
+            if self.secret[i] == '1':
+                circuit.x(i)  # Apply X gate for '1' bits
+
+        # Create shares using entanglement
+        for i in range(len(self.secret)):
+            for j in range(self.n_shares):
+                circuit.cx(i, len(self.secret) + j)  # CNOT to create shares
+
+        # Measure the shares
+        circuit.measure_all()
+
+        # Execute the circuit
+        backend = Aer.get_backend('qasm_simulator')
+        transpiled_circuit = transpile(circuit, backend)
+        qobj = assemble(transpiled_circuit)
+        result = execute(qobj, backend, shots=1024).result()
+        counts = result.get_counts()
+
+        # Extract shares from the measurement results
+        shares = []
+        for i in range(self.n_shares):
+            share = ''.join([counts.get(f"{i:0{len(self.secret)}b}", 0) for i in range(2**len(self.secret))])
+            shares.append(share)
+
+        return shares
+
+if __name__ == "__main__":
+    # Example usage for Quantum Digital Signature
+    message = "1011"
+    qds = QuantumDigitalSignature(message)
+    qds.generate_key()
+    signed_message = qds.sign()
+    print("Signed Message Counts:", signed_message)
+
+    # Example usage for Quantum Secret Sharing
+    secret = "1101"
+    n_shares = 3
+    qss = QuantumSecretSharing(secret, n_shares)
+    shares = qss.share_secret()
+    print("Shares:", shares)