在這個資訊爆炸的時代，人們使用電腦已經成為生活中不可或缺的一部分，許多以往需要當面完成的動作，如今都只要在電腦前面便可以完成。也由於電腦和網路所帶來的便利性，使得許多原本現實生活中需要當面完成的識別動作，在網路上實行起來就格外的重要。而可以輕易達成確認雙方身份的數位簽章也就因應而生。
　　
　　然而，現今在網路世界中潛藏著許多的危機，使得人們在網路上交換訊息或資料的時候格外地注重隱秘性，在一般的情況下，可用加密演算法來達成，但是有的時候需要秘密地把某些重要的資料透過一個安全的管道傳送出去；近年來有許多學者提出了將秘密資訊隱藏在數位簽章中，這樣的簽章就外表而言和一般的數位簽章相同，但對於某些知情的人而言，卻可以得到藏在數位簽章內的秘密資訊，也可同時達成身份確認的動作，這種秘密資訊傳遞的方式即稱為潛隱通道(Subliminal Channel)。在本篇論文中，我們將探討在環簽章中這類的做法，並提出二個新的做法，並以數學的方法來証明其不可分辨性(Indistinguishableness)。

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