利用Visual C++ .net2003开发的一款用于保护文件的小程序。

对文件产生MD5值同时对源文件用DES加密，并用私钥加密签名。

对加密文件解密，验证用公钥解密签名与解密文件的MD5值比较，以判断文件是否被修改。

遇到的问题：微软提供的签名函数可能有问题，无论用公钥还是私钥签名，用公钥、私钥（任一）均可解密。怪！希望在此与大家交流交流。-The use of Visual C++. Net2003 developed a document for the protection of small procedures. MD5 value of the document produced at the same time the source file using DES encryption, and signature private key encryption. Encrypted files decryption, authentication using public key to decrypt the signature and decrypt files MD5 value to determine whether a document is modified. Problems encountered: Microsoft to provide the signature function may be a problem regardless of whether it uses a public key or private key signature, using public key, private key (any one) can be decrypted. Strange! Would like to exchange with the U.S. exchanges.