Encrypts a stream with the specified symmetric provider. The returned stream is at position zero and ready to be read. - CSharp System.Security.Cryptography

CSharp examples for System.Security.Cryptography:Encrypt Decrypt

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Description

Encrypts a stream with the specified symmetric provider. The returned stream is at position zero and ready to be read.

Demo Code


using System.Security.Cryptography;
using System.IO;// www  . j  a va  2s  .co m
using System;

public class Main{
      /// <summary>
      /// Encrypts a stream with the specified symmetric provider.  The returned stream
      /// is at position zero and ready to be read.
      /// </summary>
      /// <param name="inStream">The stream to encrypt.</param>
      /// <param name="provider">The cryptographic provider to use for encryption.</param>
      /// <returns>Encrypted stream ready to be read.</returns>
      public static Stream GetEncryptedStream(Stream inStream, SymmetricAlgorithm provider) 
      {
         // Make sure we got valid input
         if (inStream == null) throw new ArgumentNullException("Invalid stream.", "inStream");
         if (provider == null) throw new ArgumentNullException("Invalid provider.", "provider");

         // Create the output stream
         MemoryStream outStream = new MemoryStream();
         CryptoStream encryptStream = new CryptoStream(outStream, provider.CreateEncryptor(), CryptoStreamMode.Write);

         // Encrypt the stream by reading all bytes from the input stream and
         // writing them to the output encryption stream.  Note that we're depending
         // on the fact that ~CryptoStream does not close the underlying stream.
         int numBytes;
         byte [] inputBytes = new byte[_bufferSize];
         while((numBytes = inStream.Read(inputBytes, 0, inputBytes.Length)) != 0) 
         {
            encryptStream.Write(inputBytes, 0, numBytes);
         }
         encryptStream.FlushFinalBlock();

         // Go back to the beginning of the newly encrypted stream and return it
         outStream.Position = 0;
         return outStream;
      }
}

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