Day 42: Homomorphic Encryption: Unleashing the Power of Privacy-Preserving Computations

Guilherme Soares
4 min readNov 11


Photo by Markus Winkler on Unsplash

“Privacy in computation is not just a feature, it’s a necessity for trust in a digital world.” — A Cryptography Scholar

In an era where data privacy and security have become paramount, homomorphic encryption stands as a beacon of hope. This innovative cryptographic technique allows computations on encrypted data (ciphertext) without ever needing to decrypt it. For software developers, understanding and implementing homomorphic encryption is a journey into the future of privacy-preserving technologies.

Understanding Homomorphic Encryption

Homomorphic encryption is a form of encryption that allows for certain types of computations to be carried out on ciphertext and generates an encrypted result which, when decrypted, matches the result of operations performed on the plaintext. It’s like being able to add two locked safes together and, upon unlocking the combined safe, finding the sum of the contents originally in each safe.

The Principle:

  • Encrypt data → Perform computations on encrypted data → Decrypt the result.
  • The decrypted result is identical to what you would get if you performed the same computations on the unencrypted data.

JavaScript Example: Implementing a Simple Homomorphic Operation

While fully homomorphic encryption (FHE) libraries are intricate and sometimes challenging to implement in JavaScript, let’s explore a simplified conceptual example using a basic add-only homomorphic system:

class SimpleHomomorphicEncryption {
constructor() {
this.key = this.generateKey();

generateKey() {
// In a real scenario, this would be a complex operation
return Math.floor(Math.random() * 100);

encrypt(data) {
// A simple 'encryption' by adding a key
return data + this.key;

decrypt(data) {
// Decrypting by subtracting the key
return data - this.key;

add(cipherText1, cipherText2) {
// Homomorphic addition: works directly on…
Guilherme Soares

I'm a senior software developer passionate about technology and to share knowledge.