網路技術的迅速發展，使得人們的生活越來越仰賴網路，不但可透過網路來傳遞語音、文字和影像，甚至也可以用來購物和付款。但網路是個公開的環境，所以個人隱私的資料便可能被截取，必須要有加密的措施使被截取的資料不被輕易的解讀。本論文是在一個以S3C2410為處理器之發展板上發展自己的網路傳輸程式，並在檔案傳輸前以RSA加密程式來加密，傳送到接收端後再經過解密程式解回原來的訊息。

RSA是目前使用上最廣泛的公開金鑰密碼系統，相當適合在公開的系統下進行私密訊息的交換，也可以用在數位簽章及身份辨識。S3C2410是Samsung所發展出來的處理器，支援觸碰式螢幕，適合用來做為PDA等手持裝置。發展板採用Linux作業系統，因為具有容易移植、良好的網路傳輸能力及周邊裝置驅動能力、且容易發展新的應用程式，而最大的優點是它的原始碼公開。

Human life gets more and more dependent on internet as it grows rapidly. By means of internet, we can not only transfer text, audio, and video data, but also buy goods and pay for them. But in a public domain like internet, private personal information can be captured easily and therefore encryption is necessary to prevent captured data readable. Based on a developing platform with Samsung S3C2410 as its CPU, this thesis develops a internet transfer application that encrypts files with RSA before sending out via internet, and decrypts them after receiving at receiver end.

RSA is currently the most popular public key cryptographic system. It's quite appropriate to use when transferring private information under public domain and it can also be used for digital signature and identification certification. S3C2410, a touch-panel-supported CPU produced by Samsung, is considered suitable for mobile devices such as PDA. Linux, the operating system we use on the developing platform, is capable of great portability, efficient network transfer, support for a great deal of peripherals, and short time to market, and most important of all is that it's open source.

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