Malware and Cryptography: Implementing Shamir Secret Sharing in C
By
cocomelonc
Summary
This article from a cybersecurity and cryptography series explores the Shamir Secret Sharing (SSS) cryptographic scheme. It explains how to split a secret (e.g., a private key or payload) into multiple shares so that no single share reveals the secret, but a threshold number of shares can reconstruct it. The post covers the mathematical foundation (polynomial interpolation over finite fields), provides a complete C language implementation with code examples, and discusses practical applications in malware development for distributed payload storage and key management. The article includes detailed explanations of prime field selection, share generation, and secret reconstruction using Lagrange interpolation.
Source
Twitter / XMalware and Cryptography: Implementing Shamir Secret Sharing in Ccocomelonc.github.ioKey quotes
· 3 pulledIn previous posts of the malware and cryptography series, we mostly looked at payload hiding: block ciphers, stream ciphers, S-boxes, DFT tricks, and other ways to transform bytes before executing or storing them.
Today I want to look at a different problem: how do we split a secret so that no single person, file, or server has enough information to recover it.
The core idea is simple: you take a secret, encode it as a point on a polynomial, and distribute shares that are other points on that same polynomial.
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