本論文以1024-bits RSA加密法保護交易的訊息，再以數位簽章處理買賣方(buyer-seller)的問題，防止買方非法散佈以及賣方假造散佈；然後將簽章編成條碼(bar-code)當作浮水印嵌入，使其具有相當高的錯誤矯正能力，只要從被破壞的影像中析出的浮水印相似度(Similarity)還在某個標準之上就可完全回復其文字型態的內容。
以條碼當作浮水印是一種完全創新的想法，以往強固性浮水印是將一個商標(meaningful logo)當作浮水印嵌入，並輔以錯誤矯正碼(error correcting code)修復破壞後的結果。而如果將要藏入的文字訊息先編成條碼，其承受破壞的能力將遠超過任何一種錯誤矯正碼，原因在於條碼才是真正有序的圖形，所謂的meaningful logo只對人眼有意義，圖檔本身其實是無序的，所以條碼可根據本身所具有的一些規則擁有強大的自我修復能力，這是使用meaningful logo再加上錯誤矯正碼也做不到的要求，這點在實驗的結果中很明顯地呈現出來。

In this thesis, we use 1024-bits RSA cryptography to protect the trade messages. We also use digital signature to prevent a buyer from unauthorized copies and to prevent a seller from forged unauthorized copies. We encode the signature with bar-code and embed the bar-code image into the original image. As long as the similarity of watermark extracts from the damaged image over a threshold, the signature can be fully recovered.
It is a new idea to bring the bar-code concept into the watermark system. The general method of robust watermark that people would utilize is to embed a meaningful logo into an image and correct the damaged watermark with error correcting code (ECC). Our simulation shows that the proposed algorithm gets much better results than that with ECC.

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