# Coding Challenge #120 - md5sum

DevFeed: [Coding Challenge #120 - md5sum](<https://devfeed.tech/articles/coding-challenge-120-md5sum-29196.md>)

Original publisher: [Read original article](<https://codingchallenges.substack.com/p/coding-challenge-120-md5sum>)

Author: John Crickett

Published: 2026-05-16T08:16:11Z

Content type: tutorial

Language: en

Sources: [Coding Challenges](<https://devfeed.tech/sources/coding-challenges.md>)

Topics: [Code Challenge](<https://devfeed.tech/topics/code-challenge.md>), [Command-line interface](<https://devfeed.tech/topics/cli.md>), [hashing](<https://devfeed.tech/topics/hashing.md>), [integrity](<https://devfeed.tech/topics/integrity.md>), [Programming](<https://devfeed.tech/topics/programming.md>), [Security](<https://devfeed.tech/topics/security.md>)

Tags: [algorithm](<https://devfeed.tech/tags/algorithm.md>), [code](<https://devfeed.tech/tags/code.md>), [coding](<https://devfeed.tech/tags/coding.md>), [command-line](<https://devfeed.tech/tags/command-line.md>), [integrity](<https://devfeed.tech/tags/integrity.md>), [security](<https://devfeed.tech/tags/security.md>), [support](<https://devfeed.tech/tags/support.md>)

## AI overview

A coding challenge guides readers through building an md5sum command-line utility. One track uses a standard or third-party library for hashing, while another implements MD5 from scratch using RFC 1321, covering file handling, check mode, message padding, the Merkle-Damgård construction, and the compression function.

## Source excerpt

This challenge is to build your own md5sum.