Encrypted Image With Hidden Data Using AES Algorithm

Abstract

Steganography is the art of hiding the fact that communication is taking place by embedding information within other data. As digital communications increase, so does the importance of techniques like steganography. Unlike cryptography, which hides the content of a message, steganography hides the existence of the message itself. Among the various formats suitable for steganography, digital images are most popular due to their prevalence online. Numerous image steganography techniques exist, each with its own strengths and weaknesses. This project presents a secure image steganography technique that encrypts both the hidden data and the image itself using the AES algorithm, providing a dual layer of security.

Index Terms: AES Algorithm, Decryption, Encryption, Steganography

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I. Introduction

With the exponential growth of data sharing over networks, protecting the confidentiality and integrity of transmitted information has become increasingly important. Image steganography offers a means to embed information within an image file. The process involves data hiding, followed by a reversible method of retrieving that data.

Reversible data hiding ensures that the hidden data can be extracted, and the original image can be restored by authorized users. The performance of such algorithms is measured based on payload capacity, complexity, visual quality, and security. Our approach enhances security by applying AES encryption to both the data and the image, requiring decryption keys for data extraction and image recovery.

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II. Advanced Encryption Standard (AES) Algorithm

AES is a symmetric key block cipher standardized by NIST in December 2001. It encrypts and decrypts data blocks of 128 bits using keys of 128, 192, or 256 bits. AES is not a Feistel structure but rather a series of mathematical transformations.

Encryption converts plaintext into ciphertext using an encryption key, while decryption reverses this process using a decryption key. AES's security, efficiency, and straightforward implementation make it ideal for applications requiring secure data transmission.

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III. Existing System

The existing system embeds data using histogram modification and contrast enhancement via histogram equalization. Peak values in the histogram are used to embed the data. Although this method improves image contrast, it involves high computation time and offers limited security.

Disadvantages:

• High computation time
• Complex algorithm with high distortion
• Less secure due to single key usage
• Time-consuming histogram generation

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IV. Proposed System

Our system introduces Distributed Source Coding (DSC) for encrypting images. The original image is encrypted using a stream cipher, and a data-hider compresses and embeds secret bits into this encrypted image.

Upon reception, the recipient—possessing the embedding and decryption keys—can extract the secret data and recover the original image losslessly. This method ensures data and image security by using distinct keys for each.

Modules:

1. Data Encryption and Hiding:

• The user selects data and an image.
• Data is encrypted using AES.
• The encrypted data is embedded into the image.

1. Image Encryption:

• The stego image (with embedded data) is encrypted and saved in PNG format.
• A password is used to encrypt the image.

1. Data and Image Retrieval:

• Only users with both keys can decrypt the image and retrieve the data.

Advantages:

• Use of two distinct keys enhances security.
• Supports both data-only and image-only retrieval.
• Complete data and image recovery for authorized users.

Architecture Diagrams:

• Image encryption with hidden data
• Collaboration diagram illustrating image provider, data hider, and receiver roles

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V. Conclusion

This dual-layer security system hides data within an image and encrypts both components. Intruders unaware of the hidden data will only see an encrypted image. Only authenticated users with both keys can retrieve the data and original image, making this system ideal for sensitive use cases such as secure medical data transmission.

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Acknowledgement

The authors would like to thank Mr. S. Venkatasubramanian, Head of the Department, and Mr. P. Dineshkumar, Supervisor, for their valuable guidance and support throughout the project.