Building an E2EE Chat App in Flask - Part 3: Keeping File Uploads Safe

May 23, 2026 · 2:43 AM UTC ·3 min read · 0 reactions · 0 comments · 30 views

#python #security #webdev #encryption #tutorial

TL;DR · WeSearch summary

The article discusses the importance of securing file uploads in an end-to-end encrypted chat application built with Flask. It outlines the potential risks associated with user-uploaded files and presents a systematic approach to mitigate these risks. Key strategies include whitelisting allowed file types, sanitizing filenames, and organizing files by type to enhance security.

Key facts

▪Users can upload potentially harmful files, including viruses and oversized files that could disrupt the application.
▪The author implemented checks to only accept specific file types, such as images and videos, while rejecting unsafe formats.
▪Filename sanitization is performed to prevent attackers from exploiting file paths to access sensitive areas of the system.

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DEV.to (Top) files mainly under programming. We currently carry 4,924 of its stories.

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Record

Original publisher	DEV.to (Top)
Canonical URL	https://dev.to/avash_karn/building-an-e2ee-chat-app-in-flask-part-3-keeping-file-uploads-safe-iid
Publication time	Sat, 23 May 2026 02:43:26 +0000
Retrieval time	2026-05-23T03:07:24.414Z
Last seen	2026-05-23T03:07:24.414Z
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Excerpt source	publisher body
Excerpt method	First ~120 words (~800 chars) of extracted publisher body, fair-use limited.
Summary	WeSearch · cerebras-chat (WeSearch summarizer)
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Cluster	SZnzhgfRvXDb · 2 stories
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Publisher visit	Yes — open original
Substitutes article?	No — link-out required for full text

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WeSearch handling by dimension

Indexing	May the item be indexed (stored, ranked, made findable)?	Allowed
Snippet	May a short excerpt of the publisher's text be shown?	Allowed
AI summary	May WeSearch generate its own short summary of the article?	Limited
Retrieval / RAG	May the content be exposed for third-party retrieval-augmented generation?	Not asserted
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Commercial reuse	May the content be reused commercially?	Not permitted

Basis: Derived from the published RSS/Atom feed. Contact: [email protected]. Reviewed: 2026-07-24.

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Opening excerpt (first ~120 words) tap to expand

try { if(localStorage) { let currentUser = localStorage.getItem('current_user'); if (currentUser) { currentUser = JSON.parse(currentUser); if (currentUser.id === 3933233) { document.getElementById('article-show-container').classList.add('current-user-is-article-author'); } } } } catch (e) { console.error(e); } Avash Karn Posted on May 23 Building an E2EE Chat App in Flask - Part 3: Keeping File Uploads Safe #python #security #tutorial #webdev E2EE chat (3 Part Series) 1 Building an E2EE Chat App in Flask - Part 1: Why Encryption Matters 2 Building an E2EE Chat App in Flask - Part 2: Secure Password Storage 3 Building an E2EE Chat App in Flask - Part 3: Keeping File Uploads Safe Okay hi, so imagine you have a mailbox at your house.

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