Core System Components & Security Controls

STEGNOLINES is divided into five core functional modules, each responsible for a distinct phase in the transformation, encryption, and spatial steganography pipeline.

1. The Five Core Functional Modules

1. User Interface (UI) Module

The primary client-facing interaction surface. Manages user inputs, real-time embedding capacity meters, interactive diagnostic visualizers (Hex Stream, PRNG distribution map, XOR difference mask), and client-side input validation to prevent buffer exhaustions or empty submissions.

2. WebAssembly Brotli Compression Engine

A compiled Rust library executing inside the browser via WebAssembly (RFC 7932). Features an adaptive thresholding routine: if the compressed byte length is strictly smaller than the raw input, the payload is prefixed with the 0xFE flag byte; otherwise, the uncompressed stream is passed forward to eliminate dictionary overhead on tiny messages.

3. Cryptographic Engine (Key Handler & AES-CTR)

Enforces strict confidentiality using standard Web Crypto primitives. Utilizes PBKDF2 with HMAC-SHA-256 across 100,000 iterations to stretch user keys into a 48-byte stream (32-byte AES key + 16-byte CTR counter IV₀), bound deterministically to the first 16 bytes of the cover text SHA-256 hash.

4. Steganographic Engine (XOR Generator & VS Codec)

Executes deterministic spatial placement. Derives a 256-bit key from the Stego-Key via PBKDF2-HMAC-SHA256 (100,000 rounds), invokes the AES-256-CTR CSPRNG with Unbiased Rejection Sampling and O(K) Lazy Fisher-Yates shuffle to select scattered bit positions in the cover text (featuring a Dual-Engine Fallback to Mulberry32 for legacy message extraction), executes bitwise XOR ($K = C_P \oplus M$), and maps key bytes to Unicode Variation Selectors (U+FE00–U+FE0F for bytes 0–15 and U+E0100–U+E01EF for bytes 16–255).

5. Chat Scanner Engine

An automated forensics and bulk extraction engine. Designed to parse multi-message conversation transcripts exported from messaging apps, isolate candidate stego messages, extract hidden Variation Selectors, and execute batch decryption without requiring manual message separation.

2. System Interfaces & Security Controls

Preventive Dual-Password Security Control

The system enforces a dual-parameter security requirement for maximum access control:

• Stego-Key: Determines the PRNG seed for spatial bit placement. If incorrect, reverse XOR yields scrambled random bits.
• Key-Base (AES Password): Derives the 256-bit cryptographic decryption key and IV counter. If omitted by the user, the system safely falls back to using the Stego-Key as the key-base.