文件的对称加密与解密

<pre name="code" class="csharp">    //Encryption,MD5 Hash Algorithm
    class MD5Encryption
    {
        public string GetMd5Hash(string input)
        {
            using (MD5CryptoServiceProvider md5=new MD5CryptoServiceProvider ())
            {
                return BitConverter.ToString(md5.ComputeHash
                    (UTF8Encoding.Default.GetBytes(input))).Replace("-","");
            }
        }
        public string GetFileMd5Hash(string filePath)
        {
            using (MD5CryptoServiceProvider md5=new MD5CryptoServiceProvider ())
            using (FileStream fs=new FileStream(filePath,FileMode.Open,FileAccess.Read,FileShare.Read))
            {
                return BitConverter.ToString(md5.ComputeHash(fs)).Replace("-", "");
            }

        }
    }

对称加密

    //Symmetric Algorithm
    class SymmetricEncryption
    {
        static int bufferSize = 128 * 1024;
        //salt key
        static byte[] salt = { 134, 216, 7, 36, 88, 164, 91, 227, 174, 76, 191, 197, 192, 154, 200, 248 };
        static byte[] iv =   { 134, 216, 7, 36, 88, 164, 91, 227, 174, 76, 191, 197, 192, 154, 200, 248 };
        private static SymmetricAlgorithm CreateRijndael(string password, byte[] salt)
        {
            PasswordDeriveBytes pdb = new PasswordDeriveBytes(password, salt, "SHA256", 1000);
            SymmetricAlgorithm sma = Rijndael.Create();
            sma.KeySize = 256;
            sma.Key = pdb.GetBytes(32);
            sma.Padding = PaddingMode.PKCS7;
            return sma;
        }
        public static void EncryptFile(string inFile, string outFile, string password)
        {
            using (FileStream infs=File.OpenRead(inFile),
                outfs=File.Open(outFile,FileMode.OpenOrCreate))
            using (SymmetricAlgorithm algorithm =CreateRijndael(password,salt))
            {
                algorithm.IV = iv;
                using (CryptoStream crypoStream=new CryptoStream (outfs,algorithm.CreateEncryptor(),CryptoStreamMode.Write))
                {
                    byte[] bytes = new byte[bufferSize];
                    int readSize = -1;
                    while ((readSize=infs.Read(bytes,0,bytes.Length))!=0)
                    {
                        crypoStream.Write(bytes, 0, readSize);
                    }
                    crypoStream.Flush();
                }
            }
        }
        public static void DecryptFile(string inFile, string outFile, string password)
        {
            using (FileStream infs=File.OpenRead(inFile),
                outfs=File.OpenWrite(outFile))
            using(SymmetricAlgorithm algorithm=CreateRijndael(password,salt))
            {
                algorithm.IV = iv;
                using (CryptoStream crypoStream=new CryptoStream (infs,algorithm.CreateDecryptor(),CryptoStreamMode.Read))
                {
                    byte[] bytes = new byte[bufferSize];
                    int readSize = -1;
                    int numReads = (int)(infs.Length / bufferSize);
                    int slack = (int)(infs.Length % bufferSize);
                    for (int i = 0; i < numReads; ++i)
                    {
                        readSize = crypoStream.Read(bytes, 0, bytes.Length);
                        outfs.Write(bytes, 0, readSize);
                    }
                    if (slack>0)
                    {
                        readSize = crypoStream.Read(bytes, 0, (int)slack);
                        outfs.Write(bytes, 0, readSize);
                    }
                    outfs.Flush();
                }
            }
        }
    }