A front-runner in modern technological advancement, machine learning relies heavily on the use of personal data. It follows that, when assessing the scope of confidentiality for machine learning models, understanding the potential role of encryption is critical. Convolutional Neural Networks (CNN) are a subset of artificial feed-forward neural networks tailored specifically for image recognition and classification. As the popularity of CNN increases, so too does the need for privacy preserving classification. Homomorphic Encryption (HE) refers to a cryptographic system that allows for computation on encrypted data to obtain an encrypted result such that, when decrypted, the result is the same value that would have been obtained if the operations were performed on the original unencrypted data. The objective of this research was to explore the application of HE alongside CNN with the creation of privacy-preserving CNN layers that have the ability to operate on encrypted images. This was accomplished through (1) researching the underlying structure of preexisting privacy-preserving CNN classifiers, (2) creating privacy-preserving convolution, pooling, and fully-connected layers by mapping the computations found within each layer to a space of homomorphic computations, (3) developing a polynomial-approximated activation function and creating a privacy-preserving activation layer based on this approximation, (4) testing and profiling the designed application to asses efficiency, performance, accuracy, and overall practicality.

Library of Congress Subject Headings

Neural networks (Computer science); Convolutions (Mathematics); Data encryption (Computer science); Data protection

Publication Date


Document Type


Student Type


Degree Name

Computer Engineering (MS)

Department, Program, or Center

Computer Engineering (KGCOE)


Marcin Lukowiak

Advisor/Committee Member

Stanislaw Radziszowski

Advisor/Committee Member

Cory Merkel


RIT – Main Campus

Plan Codes