Quantum Encryption with Certified Deletion

Functionality

This functionality allows encryption of classical data into a quantum ciphertext so that the recipient of the ciphertext can produce a deletion certificate (a classical string) which proves to the originator that the recipient can no longer obtain the original plaintext should the decryption key be revealed.

A Certified Deletion Encryption (CDE) scheme usually consists of the following 5 algorithms:

• KeyGen: This algorithm generates the key used in later stages
• Enc: This algorithm encrypts the classical plaintext into a quantum ciphertext
• Dec: This algorithm decrypts the quantum ciphertext to recover the classical plaintext
• Del: This algorithm deletes the ciphertext and generates a deletion certificate
• Ver: This algorithm verifies the deletion certificate

Properties

• Decryption-correctness: Given the ciphertext and the associated key, the probability that Dec does not output the correct plaintext is negligible in the security parameter
• Verification-correctness: Given a valid deletion certificate and its associated key, the probability that Ver does not accept the certificate is negligible in the security parameter
• Certified Deletion Security: Once the deletion certificate is issued, it becomes impossible to decrypt the certificate, even if the key is later leaked.

Protocols

• Prepare-and-Measure Certified Deletion
• Public Key Encryption with Certified Deletion
• Attribute-Based Encryption with Certified Deletion

References

• Broadbent & Islam (2019)
• Hiroka et al. (2021)