ABSTRACT:

Steganography plays a critical role in modern cybersecurity by concealing the existence of sensitive data within seemingly innocent media, such as images. This paper introduces a novel technique for data embedding using Discrete Wavelet Transform (DWT), which enables the embedding of multiple color images into a single cover image while maintaining high security. The proposed method involves decomposing both the cover and secret images into their Red, Green, and Blue (RGB) color planes. By applying N-level DWT decomposition, frequency components of the cover and secret images are merged in a way that minimizes perceptible changes to the cover image. The secret images are later extracted from the resulting stego image. This approach ensures that the changes in the cover image are subtle, preserving its visual integrity while providing robust security for the hidden data. The method demonstrates high effectiveness in securing sensitive information with minimal perceptual distortion, making it a promising technique for applications in digital steganography and information security.

INTRODUCTION:

Steganography, derived from the Greek words Steganos meaning "secret" and graphic meaning "writing," is the art and science of hiding information within other non-suspicious data. It is commonly used to protect sensitive information by embedding secret messages within various types of media such as images, videos, text, and sound. The main components of a steganographic system include the cover message (the medium used to hide the secret message), the secret message (the data to be concealed), and the embedding algorithm (the technique used to hide the secret message effectively).
While steganography can be performed in both the spatial and frequency domains, frequency domain techniques offer greater security and robustness against image manipulations. The Least Significant Bit (LSB) substitution, a popular spatial domain technique, embeds secret data in the least significant bits of the cover image, which can be easily detected with slight alterations. Consequently, it is considered unsuitable for securely transmitting confidential data. To address these vulnerabilities, frequency domain techniques such as Discrete Cosine Transform (DCT) and Discrete Wavelet Transform (DWT) are often employed.
DCT-based steganography divides an image into frequency bands (low, mid, and high) and embeds the secret data in mid-frequency bands, leaving high-frequency bands unused. While effective, DCT is susceptible to artifacts and has limitations in terms of compression. In contrast, DWT offers superior advantages for steganography. By decomposing the image into multiple levels of frequency components, DWT ensures higher compression ratios and minimizes the impact of artifacts, making it an ideal choice for embedding data securely. Furthermore, DWT’s multi-level decomposition enables the hiding of multiple secret images in a single cover image, improving data density while maintaining a high degree of imperceptibility.
This paper proposes a novel steganographic technique that embeds multiple color images into a single cover image using DWT. The cover image is decomposed into RGB color planes, with the secret images embedded in these planes after performing N-level DWT decomposition. The combined frequency components of the cover and secret images result in a stego image with minimal perceptual changes, providing high data security. This approach ensures that sensitive information remains concealed while the visual integrity of the cover image is preserved, making it a robust method for secure data transmission.

DISCRETE WAVELET TRANSFORM:

The Discrete Wavelet Transform 5 can identify portions of cover image where secret data could be effectively hidden. DWT splits information into its high and low frequency components. The high frequency part of the signal contain details about the edge components, whereas the low frequency part contains most of the signal information of the image which is again split into higher and lower frequency parts. For each level of decomposition in two dimensional applications, first DWT is performed in the vertical direction followed by horizontal direction.

PROBLEM STATEMENT:

Traditional steganographic techniques, especially spatial domain methods like LSB substitution, are vulnerable to attacks such as compression and noise addition, making them unsuitable for secure data transmission. While frequency domain techniques like DCT offer better security, they suffer from compression artifacts. Discrete Wavelet Transform (DWT) provides higher security, better compression, and improved robustness. This work aims to develop a DWT-based steganographic technique for embedding multiple color images into a single cover image while ensuring minimal perceptibility and high security.

OBJECTIVES:

1. To develop a secure steganographic technique using Discrete Wavelet Transform (DWT) for embedding multiple color images into a single cover image.
2. To ensure minimal perceptibility of the embedded data by strategically placing secret images in different frequency components of the cover image.
3. To enhance data security and robustness against common attacks such as compression, noise addition, and filtering.
4. To improve data capacity and efficiency by utilizing multi-level DWT decomposition for embedding multiple secret images.
5. To evaluate the performance of the proposed method in terms of imperceptibility, security, and extraction accuracy.