What is Single-Key FHE?

Single-key Fully Homomorphic Encryption (FHE) refers to an FHE scheme where all the homomorphic operations are performed using the same encryption key. This means that the same key is used to both encrypt the data and perform computations on the encrypted data. Here’s a more detailed explanation:

Key Characteristics of Single-Key FHE include:

Single Encryption Key:

In a single-key FHE system, there is only one encryption key that is used to encrypt data, perform homomorphic operations, and ultimately decrypt the data. This simplifies the key management process as there is no need to handle multiple keys.

Homomorphic Operations:

The core feature of FHE is the ability to perform arbitrary computations on ciphertexts, which results in a ciphertext that, when decrypted, matches the result of the operations as if they were performed on the plaintext. Single-key FHE maintains this capability using the same encryption key for all steps. Security:

Single-key FHE is useful in scenarios where a single entity needs to perform computations on encrypted data while ensuring privacy, such as secure data storage and processing. Typical applications are cloud computing and secure out-sourced data processing.