Various methods have been proposed to secure access to sensitive information over time, such as the many cryptographic methods in use to facilitate secure communications on the internet. But other methods like steganography have been overlooked which may be more suitable in cases where the act of transmission of sensitive information itself should remain a secret. Multiple techniques that are commonly discussed for such scenarios suffer from low capacity and high distortion in the output signal. This research introduces a novel steganographic approach for concealing a confidential portable document format (PDF) document within a host image by employing the Hybrid Firefly algorithm (HFA) proposed to select the pixel arrangement. This algorithm combines two widely used optimization algorithms to improve their performance. The suggested methodology utilizes the HFA algorithm to conduct a search for optimal pixel placements in the spatial domain. The purpose of this search is to accomplish two main goals: increasing the host image's capacity and reducing distortion. Moreover, the proposed approach intends to reduce the time required for the embedding procedure. The findings indicate a decrease in image distortion and an accelerated rate of convergence in the search process. The resultant embeddings exhibit robustness against steganalytic assaults, hence rendering the identification of the embedded data a formidable undertaking.

翻译：随着时间推移，人们提出了多种保护敏感信息访问安全的方法，例如互联网上用于实现安全通信的众多加密方法。然而，其他诸如隐写术等方法却被忽视了，而在信息传输行为本身需要保密的情况下，这些方法可能更为适用。针对此类场景的常见技术存在输出信号容量低、失真度高的问题。本研究提出了一种新颖的隐写方法，通过采用混合萤火虫算法选择像素排列方式，将机密便携式文档格式文件隐藏到宿主图像中。该算法融合了两种广泛应用的优化算法以提升性能。所提出的方法利用HFA算法在空间域中搜索最佳像素放置方案，旨在实现两个主要目标：提高宿主图像的容量并降低失真度。此外，该方法还旨在缩短嵌入过程所需的时间。实验结果表明，图像失真度降低且搜索过程的收敛速度加快。最终生成的嵌入结果对隐写分析攻击具有鲁棒性，使得识别嵌入数据成为一项极具挑战性的任务。