Why this project?
Steganography — hiding secret messages inside seemingly normal images — is a cornerstone technique in cybersecurity, digital forensics, and Capture The Flag competitions. While tools exist to create steganographic images, very few interactive tools let you analyze and detect hidden data visually. This project fills that gap.
What is it?
Bit Plane Analyzer decomposes any uploaded image into its constituent bit planes — isolating each individual bit position across all color channels. In standard LSB (Least Significant Bit) steganography, hidden data is encoded by flipping the least significant bits of pixel values, making changes invisible to the naked eye. By extracting and examining these bit planes individually, hidden patterns and embedded messages become immediately visible. The tool also performs chi-square statistical analysis to detect LSB embedding even when visual inspection isn't conclusive.
How does it work?
Bit Plane Decomposition: Each pixel channel (R, G, B) is stored as an 8-bit value (0–255). The tool extracts each of the 8 bit positions independently — bit 0 (LSB) through bit 7 (MSB) — creating 24 individual bit plane images. MSB planes retain most of the visible structure, while LSB planes appear as noise unless they've been modified by steganography.
Chi-Square Test: The tool compares pairs of gray levels (2n, 2n+1) in each channel's histogram. In clean images, these pairs have different frequencies. After LSB embedding, pairs become statistically indistinguishable. The chi-square statistic quantifies this deviation, flagging channels where embedding is likely.
Histogram Pair Analysis: Visual comparison of paired gray level frequencies across all channels, highlighting anomalies that suggest data embedding.
How to use it
- Upload: Drag and drop an image onto the upload zone, or click to select a file. Supports PNG, BMP, and WebP (avoid JPEG due to lossy compression destroying LSB data).
- Bit Planes: Click any button in the Bit Plane Explorer to view a specific channel and bit position. The
R-0 through B-7 buttons show individual planes; Combined shows the original image.
- Chi-Square: The statistical analysis panel shows per-channel chi-square values. Green = likely clean. Red = suspicious (potential steganography).
- Histogram: Paired gray level frequency bars for each channel. Look for unusually matched pairs — a sign of LSB modification.
- Metadata: File and image dimensions, bit depth, and color space information.
- Tip: If you're analyzing a CTF challenge, focus on the LSB planes (bit 0) — especially the Red channel, which is most commonly used for LSB embedding.