Status & Updates

⚠ Breaking Change: This update introduces Brotli compression and file/document embedding, which required a new payload format. The old and new formats are not interchangeable — images encoded with previous versions cannot be decoded by the new version, and vice versa.

What this means for you: Decode any existing stego images before updating. After updating, re-encode them with the latest version. Update Phasm on all your devices to ensure cross-platform interoperability.

Phasm now compresses your message payload with Brotli before encrypting and embedding it. Brotli delivers excellent compression ratios on short text, meaning you can fit longer messages into the same image — or use a smaller image for the same message.

Compression is applied automatically on encode and transparently decompressed on decode. No configuration needed.

You can now attach files and documents to your hidden messages. The file is embedded alongside your text inside the stego image, encrypted with the same passphrase.

On decode, the recipient receives both the text message and the attached file. Supported on all platforms (iOS, Android, and Web).

Fortress mode is a new Armor sub-mode that survives aggressive social media recompression, including WhatsApp. It uses Block-Average QIM (BA-QIM) to embed one bit per 8x8 DCT block in the block-average brightness domain.

Fortress activates automatically for short messages when using Armor mode. Images must be pre-resized to 1600px and pre-settled at QF75 before encoding. Adaptive Watson masking adjusts the quantization step per block based on visual texture, balancing image quality and robustness.

Phasm offers two steganography modes to match your threat model:

• Armor (default) — STDM embedding with Reed-Solomon error correction and adaptive repetition coding. Designed to survive JPEG recompression, resizing, and social media pipelines.
• Ghost — J-UNIWARD cost function with Syndrome-Trellis Coding. Optimized for stealth: minimizes statistical detectability so the image looks untouched to analysis tools.

Select your mode when encoding. On decode, Phasm auto-detects the mode — no guesswork required.

Every hidden message is encrypted with AES-256-GCM-SIV, a misuse-resistant authenticated cipher. The encryption key is derived from your passphrase using Argon2id, a memory-hard key derivation function that resists brute-force attacks.

All cryptographic operations happen entirely on your device. Your passphrase is never transmitted, stored, or logged — not even when using Phasm Share cloud links.

Share your stego images by uploading them to Phasm Share and sending the recipient a short phasm.link URL. After encoding, tap the Phasm Share button to upload and get a link like phasm.link/XVQhXBUe.

The recipient opens the link in any browser, enters the passphrase, and the message is decoded client-side via WebAssembly. Links expire automatically (configurable from 1 hour to 24 hours). Decoding always happens on-device — the server never sees your passphrase or plaintext.