Prepare-and-Measure Certified Deletion

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This example protocol implements the functionality of Quantum Encryption with Certified Deletion using single-qubit state preparation and measurement.



The scheme consists of 5 circuits-

  • Key: This circuit generates the key used in later stages
  • Enc: This circuit encrypts the message using the key
  • Dec: This circuit decrypts the ciphertext using the key and generates an error flag bit
  • Del: This circuit deletes the ciphertext state and generates a deletion certificate
  • Ver: This circuit verifies the validity of the deletion certificate using the key



Protocol Description

Circuit 1: Key

The key generation circuit

Input : None

Output: A key state

  1. Sample
  2. Sample where
  3. Sample
  4. Sample
  5. Sample
  6. Sample
  7. Sample
  8. Output

Circuit 2: Enc

The encryption circuit

Input : A plaintext state and a key state

Output: A ciphertext state

  1. Sample where
  2. Compute where
  3. Compute
  4. Compute
  5. Output

Circuit 3: Dec

The decryption circuit

Input : A key state and a ciphertext

Output: A plaintext state and an error flag

  1. Compute
  2. Measure in the computational basis. Call the result
  3. Compute where
  4. Compute
  5. If , then set . Else, set
  6. Compute
  7. Output

Circuit 4: Del

The deletion circuit

Input : A ciphertext

Output: A certificate string

  1. Measure in the Hadamard basis. Call the output y.
  2. Output

Circuit 5: Ver

The verification circuit

Input : A key state and a certificate string

Output: A bit

  1. Compute where
  2. Compute
  3. If , output . Else, output .

Further Information