Fully Homomorphic Encryption

November 21, 2023 - Around 3 mins mins to read

Understanding Fully Homomorphic Encryption

Fully Homomorphic Encryption (FHE) is a specific type of encryption scheme that allows computations to be performed on encrypted data without the need for decryption. The primary goal of FHE is to enable computations on ciphertexts without decrypting the data for intermediate steps during the computation process.

This unique functionality of FHE is particularly beneficial in scenarios such as cloud computing and big data analytics, where large amounts of data need to be processed while maintaining the privacy of sensitive or proprietary information from third parties.

Initially, the concept of performing operations on encrypted data may seem impossible. How can operations like addition and multiplication be performed on data without decrypting it?

The challenge arises from the fact that traditional encryption schemes have separate keys for encryption and decryption, and performing operations on encrypted data requires decrypting it first.

However, with Fully Homomorphic Encryption (FHE), an encryption key is used, but unlike traditional schemes, computations can be performed on plaintext in an arbitrary manner without the need for decryption.

The Advantages of Homomorphic Encryption

Fully Homomorphic Encryption offers a highly valuable property by enabling computation on sensitive data without exposing it to the entity performing the computation.

For example, consider a scenario where a database of medical information is fully homomorphically encrypted. In this case, a doctor can be provided with an encryption key, allowing them to perform queries on the database to determine whether patients with specific symptoms have been treated. This enables the doctor to obtain information about their patients without accessing the actual data stored in the database.

Distinguishing FHE from Other Forms of Homomorphic Encryption

Homomorphic encryption encompasses various types based on the possibility of computations over encrypted data, including partially homomorphic, somewhat homomorphic, leveled fully homomorphic, and fully homomorphic encryption.

Partially homomorphic and somewhat homomorphic encryption only support specific types of operations on encrypted data, and their repetition is limited.

In contrast, fully homomorphic encryption allows an unlimited number of operations to be performed on encrypted data, without any restrictions on repetition.

Benefits of Fully Homomorphic Encryption

FHE enables the storage of sensitive private data on third-party servers while allowing computation on that data without compromising its encryption. This ensures that server administrators cannot access the details of the computations performed on the private data, assuming a secure FHE implementation.
FHE eliminates the tradeoff between data usability and privacy. It preserves data privacy without the need to mask or remove any features.
A properly implemented FHE scheme provides high resilience against quantum attacks, making it quantum-safe.

However, it is important to note that FHE is still an emerging technology and is currently considered commercially infeasible. Extensive research and development are required before it can be widely adopted.

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