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SSGAN: Secure Steganography Based on Generative Adversarial Networks

Haichao Shi, Jing Dong, Wei Wang, Yinlong Qian, Xiaoyu Zhang

arXiv:1707.01613v4cs.CVcs.MM

TL;DR

Secure steganography needs covers that conceal messages while remaining difficult to detect. The paper proposes SSGAN, using WGAN-generated covers, embedding methods, and GNCNN-based assessment; experiments report faster convergence, improved visual quality, and more secure covers, including with random keys.

  • Problem

    Secure steganography is difficult because existing schemes may require unavailable cover-distribution priors and often incorporate steganalysis heuristically.

  • Method

    SSGAN generates cover images with WGAN, embeds messages using methods such as HUGO, and uses GNCNN to assess steganographic operations and embedding suitability.

  • Results

    The experiments report faster convergence than DCGAN, higher visual quality, more difficult detection, and suitability for embedding with random keys.

  • Takeaways & Limitations

    SSGAN provides a generative-adversarial approach for producing more suitable and secure steganographic covers, with evaluation on CelebA datasets.

Abstract

from arXiv · show

In this paper, a novel strategy of Secure Steganograpy based on Generative Adversarial Networks is proposed to generate suitable and secure covers for steganography. The proposed architecture has one generative network, and two discriminative networks. The generative network mainly evaluates the visual quality of the generated images for steganography, and the discriminative networks are utilized to assess their suitableness for information hiding. Different from the existing work which adopts Deep Convolutional Generative Adversarial Networks, we utilize another form of generative adversarial networks. By using this new form of generative adversarial networks, significant improvements are made on the convergence speed, the training stability and the image quality. Furthermore, a sophisticated steganalysis network is reconstructed for the discriminative network, and the network can better evaluate the performance of the generated images. Numerous experiments are conducted on the publicly available datasets to demonstrate the effectiveness and robustness of the proposed method.

1 Introduction

The paper frames secure steganography as designing covers that conceal messages while accounting for steganalysis. SSGAN generates suitable covers with improved visual quality, security assessment, and embedding suitability.

  • Secure steganography must conceal messages without detectable hidden content, making secure scheme design important for secret communications.
  • Existing schemes often require difficult-to-obtain cover-distribution priors and conventionally account for steganalysis only heuristically.
  • The paper focuses on spatial-domain steganography and considers ±1-embedding alongside content-adaptive methods such as HUGO, WOW, and S-UNIWARD.
  • The proposed SSGAN generates covers first, embeds messages using methods such as HUGO, and then uses GNCNN to detect steganographic operations.
  • Perceptibility: WGAN replaces DCGAN to generate cover images with higher visual quality and faster training.
  • Security and Diversity: GNCNN assesses generated-image suitability instead of an earlier steganalysis network, while also competing against the generator to improve embedding suitability.

2 Secure Steganography Based on Generative Adversarial Networks

SSGAN uses adversarial learning to generate realistic, secure steganographic covers by training one generator against separate visual-quality and steganalysis discriminators. WGAN generation, a steganalysis-focused S network, and joint update rules target image realism and embedding suitability.

  • Adversarial Learning: Adversarial training jointly updates a generator and discriminator, with D distinguishing real from generated samples and G learning to produce similar data.Each iteration performs gradient ascent on D followed by gradient descent on G.
  • Adversarial Learning: WGANs are used to generate and discriminate images through adversarial training, addressing traditional GAN training difficulty described in the paper.The paper motivates WGANs in the context of improving the generation and discrimination process.
  • Model Design: SSGAN contains one generative network and two discriminative networks that evaluate visual quality and steganographic suitability.The generator is trained to compete against both D and the steganalysis network S.
  • Model Design: A convex combination of D and S, controlled by α ∈[0,1], balances generated-image realism against steganalysis evaluation.The paper reports that α ≤0.7 produces results closer to the noise.
  • Generator G: The generator uses a fully connected layer, four fractionally-strided convolution layers, and a hyperbolic tangent layer to generate secure covers.This architecture is presented as the generative network structure in Fig. 2.
  • Discriminators D and S: D evaluates visual quality with four convolutional layers and a fully connected layer, while S applies a predefined high-pass filter before convolutional and classification layers.S is designed to assess the suitability of generated images for information hiding.
  • Update Rules: The update rules train G, D, and S separately, with G maximizing errors from both D and S rather than only D.The paper describes this objective as maximizing the normalization errors of D and S.

3 Experiments

Experiments evaluate SSGAN’s visual quality, convergence, and steganographic security using CelebA images and steganalysis networks. Results indicate improved image quality, faster WGAN convergence, and greater resistance to detection, including under random-key conditions.

  • 3.1 Data preparation: Experiments use CelebA images cropped to 64 × 64 pixels, with separate training and testing sets for steganalysis.The resulting steganography datasets contain 380,000 training images and 20,000 testing images.
  • 3.1 Data preparation: SSGAN and SGAN images are compared after seven training epochs, with SSGAN producing higher visual quality.The comparison uses generated examples from the CelebA dataset.
  • 3.1 Data preparation: WGAN provides faster convergence and a more pronounced effect than DCGAN in the seven-epoch runtime comparison.The paper reports this comparison in Table 1.
  • 3.2 Experimental Setup: The first security experiment embeds messages in real and generated images, then evaluates them with a steganalysis network.Embedding uses LSB Matching with a payload of 0.4 bits per pixel.
  • 3.2 Experimental Setup: SSGAN increases classification error rates relative to ordinary WGAN-generated images, indicating more secure steganographic carriers.The paper reports that ordinary WGAN synthetic images can be easily detected by a steganalyser.
  • 3.3 Discussion: Using GNCNN, SSGAN-generated images become more difficult to detect while also achieving better and more realistic visual quality.The generated-image experiments follow conditions S1–S3 and use an independent steganalyser network for evaluation.

4 Conclusion And Future Work

The paper concludes that SSGAN can generate suitable, visually improved, and more secure steganographic covers. It reports suitability for random-key embedding and identifies adaptive steganography for social networks as a future use.

  • 4 Conclusion And Future Work: SSGAN generates covers with higher visual quality and suitability for embedding with a random key.The model is evaluated on the CelebA dataset and is reported to produce more secure covers for steganography.
  • 4 Conclusion And Future Work: The authors suggest SSGAN could support adaptive steganographic algorithms for social networks.They also state that exploring additional steganography properties could improve performance.
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