Prepare-and-Measure Certified Deletion

Revision as of 03:29, 2 February 2022 by Chirag (talk | contribs)


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

Assumptions

Outline

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

Notation

Properties

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

References