BPCS (Bit-Plane Complexity Segmentation) steganography in CrypTool 2

Welcome to this demonstration of Bit-Plane Complexity Segmentation (BPCS) Steganography using CrypTool 2! This video showcases the practical implementation of digital information hiding, a core concept in cryptography and steganography. This demonstration is part of the IKB21303 "Cryptography & Steganography" course at Universiti Kuala Lumpur (UniKL MIIT). What is BPCS Steganography? BPCS steganography is a technique used to hide secret data within an insignificant part of a cover medium (like an image) without causing noticeable degradation to the cover. It leverages the "complexity" of bit planes in an image to identify suitable areas for embedding data. Demonstration Overview: In this video, I will walk you through the process of embedding a secret message into a 24-bit BMP image and then extracting it, verifying the integrity of the hidden data. This process adheres to the guidelines of our Lab Assignment 2. Step-by-Step Process Shown in This Video: Setting Up the Workspace in CrypTool 2: We begin by opening CrypTool 2 and creating a new workspace. This provides a clean canvas for our steganography operations. Loading the Cover Image: An "Image" component is dragged onto the workspace. For this demonstration, we use a 24-bit BMP image (e.g., lena.bmp) as our cover medium. This is the image that will carry our hidden secret. Preparing the Secret Data: A "File Input" component is added to load our secret message, typically a .txt file (e.g., secret.txt). In this example, the secret file is a text document. You can see the secret.txt file in my project folder. Adding the BPCS Steganography Component: The core of our operation is the "BPCS Steganography" component, which is searched for and dragged into the workspace. Connecting the Components (Embedding Phase): The "Image" component (our cover image) is linked to the "Cover Image" input of the BPCS component. The "File Input" component (our secret data) is linked to the "Secret Data" input of the BPCS component. Configuring BPCS Parameters for Embedding: We double-click the BPCS component to set its parameters. The Threshold (α) is set to 0.3, which defines the complexity tolerance for embedding. The mode is explicitly set to "Embed". (Optionally, "Encrypt before embedding" can be checked for added security). Executing the Embedding Process: By right-clicking the BPCS component and selecting "Execute," the embedding process begins. Once completed, our secret data is hidden within the cover image. Saving the Stego Image: The output of the BPCS component is connected to an "Image Output" component. The resulting image, now containing the hidden data, is saved as stego_image.bmp. You can see this stego_image.bmp file in my project folder. Extracting the Secret Data (Verification Phase): To verify our work, a new BPCS component is added, and its mode is set to "Extract". The stego_image.bmp (our stego image) is connected to its "Cover Image" input. A "File Output" component is connected to the "Secret Data" output of this extraction BPCS component. After execution, the extracted data is saved as extracted_secret.txt. You can see this extracted_secret.txt file in my project folder. Validating the Results: The crucial final step is to compare the original secret.txt with the extracted_secret.txt to ensure that the secret data was fully recovered and matches the original bit-for-bit, proving the success of our BPCS steganography implementation. My screenshots show that the secret and extracted_secret files both have a size of 1 KB, indicating a successful extraction.