stegstr

name	stegstr
summary	Embed and decode hidden messages in PNG images. Steganographic Nostr client for hiding data in images—works offline, no registration.
description	Decode and embed Stegstr payloads in PNG images. Use when the user needs to extract hidden Nostr data from a Stegstr image, encode a payload into a cover PNG, or work with steganographic social networking (Nostr-in-images). Supports CLI (stegstr-cli decode, detect, embed, post) for scripts and AI agents.
license	MIT
tags	steganography, nostr, images, crypto, integration, file-management, automation, cli
install	{"requirements":"- Rust (latest stable) - https://rustup.rs\n- Git\n","steps":"1. git clone https://github.com/brunkstr/Stegstr.git\n2. cd Stegstr/src-tauri && cargo build --release --bin stegstr-cli\n3. Binary: target/release/stegstr-cli (Windows: stegstr-cli.exe)\n"}
permissions	["filesystem"]
metadata	{"homepage":"https://stegstr.com","for-agents":"https://www.stegstr.com/wiki/for-agents.html","repo":"https://github.com/brunkstr/Stegstr"}

Stegstr

Stegstr hides Nostr messages and arbitrary payloads inside PNG images using steganography. Users embed their feed (posts, DMs, JSON) into images and share them; recipients use Detect to load the hidden content. No registration, works offline.

When to use this skill

• User wants to decode (extract) hidden data from a PNG that contains Stegstr data.
• User wants to embed a payload into a cover PNG (e.g. Nostr bundle, JSON, text).
• User mentions steganography, Nostr-in-images, Stegstr, hiding data in images, or secret messages in photos.
• User needs programmatic access for automation, scripts, or AI agents.

CLI (headless)

Build the CLI from the Stegstr repo:

git clone https://github.com/brunkstr/Stegstr.git
cd Stegstr/src-tauri
cargo build --release --bin stegstr-cli

Binary: target/release/stegstr-cli (or stegstr-cli.exe on Windows).

Decode (extract payload)

stegstr-cli decode image.png

Writes raw payload to stdout. Valid UTF-8 JSON is printed as text; otherwise base64:<data>. Exit 0 on success.

Detect (decode + decrypt app bundle)

stegstr-cli detect image.png

Decodes and decrypts; prints Nostr bundle JSON { "version": 1, "events": [...] }.

Embed (hide payload in image)

stegstr-cli embed cover.png -o out.png --payload "text or JSON"
stegstr-cli embed cover.png -o out.png --payload @bundle.json
stegstr-cli embed cover.png -o out.png --payload @bundle.json --encrypt

Use --payload @file to load from file. Use --encrypt so any Stegstr user can detect. Use --payload-base64 <base64> for binary payloads.

Post (create kind 1 note bundle)

stegstr-cli post "Your message here" --output bundle.json
stegstr-cli post "Message" --privkey-hex <64-char-hex> --output bundle.json

Creates a Nostr bundle; use stegstr-cli embed to hide it in an image.

Example workflow

# Create a post bundle
stegstr-cli post  --output bundle.json


stegstr-cli embed cover.png -o stego.png --payload @bundle.json --encrypt


stegstr-cli detect stego.png