A retrospective study on NTRU cryptosystem

Homomorphic Encryption, a magic wand in the field of cryptography that enables the user to perform secure computation over encrypted data, without decrypting the data. It allows cloud service providers to have access to encrypted data instead of original data, which also facilitates secure computation over encrypted data along with the secure transmission of it. NTRU, open-source public-key cryptography, based on lattices, is one of the standards of Homomorphic Encryption, can be used for secure outsourcing, the transmission of data, and performing computation on encrypted data. NTRU scheme is not vulnerable to quantum computer-based attacks, unlike existing traditional cryptographic techniques. In this paper, NTRU, the homomorphic encryption scheme is reviewed. The different variants of NTRU are also explainedthrough a detailed literature studybased on ring structure.The analysis also has been done that may help researchers to have a clear understanding of NTRU and its different variants and to distinguish them easily. The availability of different types of fields, rings based on different structures, different algebra, etc. for implementation of NTRU opens a new way for researchers to explore them to achieve a more efficient NTRU scheme for real-life applications.