Camenisch-Shoup Verifiable Encryption using Kryptology and Golang
So Alice has some ciphertext. How does Bob prove to Alice that he has used a certain key to encrypt the message? Well, one way is for Bob to provide a Non-interactive Zero-Knowledge Proof (NIZK), and which will not only prove the party who encrypted the message but also the party who has the secret key.
The encryption key might have been sourced from Trent and who has a public key (pk) and a secret key (sk). Then Bob might encrypt his secret key with Trent’s public key (pk) and then give this to Alice. Alice might then ask Bob to prove that the ciphertext will be decrypted using Trent’s secret key (sk). Bob is thus a proxy in-between and using Trent’s public key to encrypt his secret key.
For this, we bind to some public data —known as a label — within the encryption and decryption processes. Alice thus attaches a label to the ciphertext that defines the conditions for decryption, such as related to the expiration time or to Alice’s identity. If the decryption then takes place with a different label, it will not reveal anything about the original message. Along with this, verifiable encryption can be used by Alice to ask Trent for a proof that he has decrypted the ciphertext correctly.
Another application is within a fair exchange of data, and where Bob and Alice exchange data. With…
