A character-mapping technique based on letter frequency for enhancing feature-based text steganography

In the field of text steganography, researchers introduce diverse techniques to ensure that the hidden information remains undetectable. One widely used technique is feature-based text steganography, which involves modifying the features of characters in the text. However, this technique faces challenges of delivering and preserving the security of information while altering the characters in the cover text. The character dependency limits the utilization of cover text, as the concealment of the hidden text depends on the availability of provided characters. This study aims to overcome character dependency issue in the feature-based text steganography by proposing the Character-Mapping technique. The objectives include designing, developing, and evaluating the Character-Mapping technique within a text steganography system implemented based on a Java platform prototype. The proposed Character-Mapping technique utilizes the frequency of letters in English text to conceal the hidden text, according to the established character-mapping table. In addition, the study conducts a comparison between the proposed technique and the two existing techniques, Bit- One-Count and Extended-1 using capacity, imperceptibility, and robustness as the three evaluation aspects to assess their performance. Experimental results imply that the Character-Mapping technique attains a capacity ratio of 0.024, an imperceptibility ratio of 0.904, and a robustness level of 99.98%. The performance analysis demonstrates that the proposed Character-Mapping technique provides a good capacity, imperceptibility, and robustness. The proposed Character-Mapping technique enhances feature-based text steganography in overcoming the character dependency limitation. It preserves the naturalness of the cover text while maintaining resistance against modification. The findings contribute to improving the applicability of the feature-based technique in safeguarding text concealment