The current online digital world, consisting of thousands of newspapers, blogs, social media, and cloud file sharing services, is providing easy and unlimited access to a large treasure of text contents. Making copies of these text contents is simple and virtually costless. As a result, producers and owners of text content are interested in the protection of their intellectual property (IP) rights. Digital watermarking has become crucially important in the protection of digital contents. Out of all, text watermarking poses many challenges, since text is characterized by a low capacity to embed a watermark and allows only a restricted number of alternative syntactic and semantic permutations. This becomes even harder when authors want to protect not just a whole book or article, but each single sentence or paragraph, a problem well known to copyright law. In this paper, we present a fine-grain text watermarking method that protects even small portions of the digital content. The core method is based on homoglyph characters substitution for latin symbols and whitespaces. It allows to produce a watermarked version of the original text, preserving the anonymity of the users according to the right to privacy. In particular, the embedding and extraction algorithms allow to continuously protect the watermark through the whole document in a fine-grain fashion. It ensures visual indistinguishability and length preservation, meaning that it does not cause overhead to the original document, and it is robust to the copy and past of small excerpts of the text. We use a real dataset of 1.8 million New York articles to evaluate our method. We evaluate and compare the robustness against common attacks, and we propose a new measure for partial copy and paste robustness. The results show the effectiveness of our approach providing an average length of 101 characters needed to embed the watermark and allowing to protect paragraph-long excerpt or smaller the 94.5% of the times.

中文翻译：

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细粒度水印保护知识产权

当前的在线数字世界由数千种报纸，博客，社交媒体和云文件共享服务组成，可轻松无限制地访问大量的文本内容。复制这些文本内容非常简单，而且几乎没有成本。结果，文本内容的生产者和所有者对保护其知识产权（IP）感兴趣。数字水印在保护数字内容方面已变得至关重要。总而言之，文本水印提出了许多挑战，因为文本的特点是嵌入水印的能力低，并且仅允许有限数量的替代句法和语义排列。当作者不仅要保护整本书或文章，而且要保护每个句子或段落时，这就变得更加困难。版权法众所周知的问题。在本文中，我们提出了一种细粒度的文本水印方法，该方法可以保护即使是一小部分的数字内容。核心方法基于对拉丁符号和空格的象形文字替换。它允许产生原始文本的水印版本，并根据隐私权保护用户的匿名性。特别地，嵌入和提取算法允许以细粒度的方式连续保护整个文档中的水印。它确保了视觉上的可区分性和长度保留，这意味着它不会对原始文​​档造成开销，并且对于文本的较小摘录的复本和过去具有鲁棒性。我们使用180万纽约文章的真实数据集来评估我们的方法。我们评估并比较了针对常见攻击的鲁棒性，并提出了一种针对部分复制和粘贴鲁棒性的新措施。结果表明，我们的方法有效，可提供嵌入水印所需的平均101个字符的长度，并可以保护94.5％的段落或以下段落摘要。