The Dalì Attack on Digital Signature 1
The Dalì Attack on Digital Signature 1
复制标题
Dalì 对数字签名的攻击 1
DOI：
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复制
发表时间：
2008
期刊：
影响因子：
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通讯作者：
G. Lax
中科院分区：
文献类型：
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作者：
F. Buccafurri;G. Caminiti;G. Lax
最近的文献主要在数字签名的背景下对电子文档的模糊表示问题进行了深入的研究。实际上，尽管数字签名的预期目标是保证任何签名文档的完整性，但上述问题表明，其内容的可视化可能因上下文而异。文献中已知的歧义的主要来源是许多文档格式的特征，即根据某些嵌入式指令的执行具有动态表示。例如，PDF文件可能包含java脚本。当文档可以导入外部字体时，可能会出现类似的问题。从这个角度来看，人们普遍认为某些格式，如图像（位图，tiff等）和纯文本（以及某些特定格式，如PDF/A）是非常安全的，因为这些格式的文档不能是动态的。因此，大多数国家的技术规则强烈建议在需要高度信任的情况下签署文件。在本文中，我们提出了一种新的电子文档歧义源，它也可能涉及图像文件，使我们能够实现一种针对数字签名的新型攻击，旨在获得具有不同于签名者所期望的潜在（法律）效果的签名文档。文中通过实例证明了这种攻击方法，并给出了一种可能的对比方法。
The problem of ambiguous presentation of electronic documents has been deeply investigated in the recent literature mainly in the context of digital signature. Indeed, despite the intended goal of digital signature to guarantee the integrity of any signed document, the above problem demonstrates that the visualization of its content might vary, depending on the context. The main source of ambiguity known in the literature is the feature of many document formats to have a dynamic presentation depending on the execution of some embedded instruction. This is for example the case of PDF files which may incorporate java scripts. A similar problem may occur whenever a document can import external fonts. It is widely accepted that some formats like image (bitmap, tiff, etc.) and plain text (beside some specific format like PDF/A) are extremely safe from this point of view, since documents in these formats cannot be dynamic. As a consequence they are strongly recommended by technical rules of most countries for documents being signed in case a high level of trust is required. In this paper we present a new source of ambiguity of electronic documents which may regard also image files, allowing us to implement a new type of attack on digital signature aimed to obtain signed documents with potential (legal) effects different from those desired by the signer. The paper proves the attack by example and gives a possible way to contrast it.