Phasm: Steganography
Hide Messages in Photos
Free · Designed for iPad
Hide encrypted messages and files inside ordinary photos. Ghost mode resists detection. Armor mode survives recompression. No account needed. Processing stays on device.
Hidden in plain sight.
Phasm hides your messages — and files — inside ordinary photos using steganography. The photo looks identical to the human eye, but it carries encrypted data that only the intended recipient can extract with the right passphrase.
TWO MODES FOR TWO NEEDS
• Ghost Mode — Maximum stealth. Uses advanced adaptive steganographic algorithms (J-UNIWARD + syndrome-trellis coding) to make hidden data virtually undetectable, even by statistical steganalysis tools. Supports file embedding: attach documents, images, or archives alongside your message. When you use a non-JPEG photo, Deep Cover mode activates automatically for even greater capacity.
• Armor Mode — Maximum durability. Your hidden message survives JPEG recompression, cross-library re-encoding, and mild cropping. Fortress sub-mode auto-activates for short messages and survives aggressive compression from popular messaging apps.
SERIOUS ENCRYPTION
• AES-256-GCM-SIV authenticated encryption on every message — always on, not optional.
• Argon2id key derivation — resistant to brute-force and GPU attacks.
• ChaCha20-based deterministic randomness for embedding.
• Post-quantum safe — 256-bit symmetric encryption remains secure against quantum computers.
• No backdoors. No key escrow. You hold the only key.
PRIVACY BY DESIGN
• All encoding and decoding happens on your device. Nothing is uploaded.
• No account required. No sign-up. No tracking. No ads.
• Open-source Rust cryptographic engine — auditable by anyone.
• Designed for journalists, researchers, activists, curious tinkerers — or just for fun.
SHARE YOUR WAY
• Share stego photos via AirDrop, Messages, email, or any app that handles images.
• phasm.link — generate a short link so recipients can decode without installing anything, right in the browser or via App Clip.
• For guaranteed delivery through messaging apps, use "send as file" to prevent recompression.
BUILT FOR iPHONE AND iPAD
• Native SwiftUI interface optimized for both iPhone and iPad.
• Floating tab bar on iPad. Two-column layouts on larger screens.
• Supports JPEG, PNG, GIF, WebP, HEIC, and progressive JPEG input — auto-converted for embedding.
• Real-time decode progress with integrity scoring.
• Brotli-compressed payloads for maximum capacity.
• 37 languages supported.
HONEST ABOUT LIMITATIONS
• Social media platforms that resize or re-encode photos may destroy hidden data. Use direct sharing or "send as file" for reliable delivery.
• Message capacity depends on image resolution — larger photos carry more data.
• Steganography hides the existence of a message. Encryption protects its content. Phasm gives you both.
Ratings & Reviews
This app hasn’t received enough ratings or reviews to display an overview.
Deep Cover Mode
Ghost mode now automatically activates SI-UNIWARD when you use a non-JPEG photo — PNG, screenshot, or straight from your camera. ~43% more steganographic capacity with even better stealth. Look for the green "Deep Cover" indicator below the capacity bar.
Smarter Capacity Bar
The capacity indicator now updates in real-time when attaching or removing files, with accurate readings across all modes.
Accurate Algorithm Details
Cryptographic and steganographic method descriptions throughout the app now correctly reflect AES-256-GCM-SIV encryption, J-UNIWARD + STC coding, and STDM + Reed-Solomon error correction.
Stability & Performance
Core engine hardening, safer code patterns, and cleanup across the entire codebase.
The developer, Christoph Gaffga, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Linked to You
The following data may be collected but it is not linked to your identity:
- Usage Data
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Christoph Gaffga
- Size
- 19.6 MB
- Category
- Utilities
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later. - iPad
Requires iPadOS 17.0 or later. - Mac
Requires macOS 14.0 or later and a Mac with Apple M1 chip or later.
- Languages
English and 34 more
- English, Arabic, Bengali, Croatian, Czech, Danish, Dutch, French, German, Greek, Hausa, Hebrew, Hindi, Hungarian, Indonesian, Italian, Japanese, Korean, Malay, Norwegian Bokmål, Persian, Polish, Portuguese, Romanian, Russian, Simplified Chinese, Slovak, Spanish, Swahili, Swedish, Thai, Turkish, Ukrainian, Urdu, Vietnamese
- Age Rating
4+
- 4+
- Copyright
- © 2026 Christoph Gaffga