Hybrid Cryptography & Homomorphic Encryption

A mixed approach ! Cryptography is a science, Whenever we use the word cryptography, Encryption and Decryption comes to our mind. Encryption, that is simply the process of converting plain-text into unintelligible text generally known as called cipher-text. While Decryption is the reverse process that is moving from the unintelligible cipher-text back to plain-text.

Two basic themes or types of Encryption are there, Symmetric encryption which is also referred to as private key cryptography is a type of encryption technique where same key is used for performing both encryption and decryption. Furthermore Asymmetrical encryption is also known as public key cryptography, it is a type of encryption technique which uses two keys (A set of private key and public key) to encrypt a plain text.

Hybrid Cryptography is a method of encryption that consolidations at least two encryption. It incorporates a combination of asymmetric and symmetric encryption to benefit from the strengths of each form of encryption.

To encrypt a message addressed to Alice in a hybrid crypto-system, Bob does the following:

1. Obtains Alice’s public key.
2. Generates a fresh symmetric key for the data encapsulation scheme.
3. Encrypts the message under the data encapsulation scheme, using the symmetric key just generated.
4. Encrypt the symmetric key under the key encapsulation scheme, using Alice’s public key.
5. Send both of these encryptions to Alice.

To decrypt this hybrid cipher-text, Alice does the following:

1. Uses her private key to decrypt the symmetric key contained in the key encapsulation segment.
2. Uses this symmetric key to decrypt the message contained in the data encapsulation segment.

Homomorphic Encryption

Homomorphism, two different structures of the same type (such as two groups, two rings, or two vector spaces). The word homomorphism comes from the ancient Greek language. “homo” meaning same and “morphe” meaning form or shape.

Homomorphic encryptions enable complex scientific tasks to be performed on scrambled information without trading off the encryption. without expecting access to the secret key. The results of the calculations are encoded, and can be decrypted only by the proprietor of the secret key.

Homomorphic encryption is required to have a vital influence in distributed computing, enabling organizations to store encoded information in an open cloud and exploit the cloud supplier’s systematic administrations and analytical services.

Example taken from “https://en.m.wikipedia.org/wiki/Hybrid_cryptosystem”