Decrypts a stream with the specified symmetric provider. - CSharp System.Security.Cryptography

CSharp examples for System.Security.Cryptography:Encrypt Decrypt

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Description

Decrypts a stream with the specified symmetric provider.

Demo Code


using System.Security.Cryptography;
using System.IO;// w  ww. j a v a  2s.c  o  m
using System;

public class Main{
        /// <summary>
      /// Decrypts a stream with the specified symmetric provider.
      /// </summary>
      /// <param name="inStream">The stream to decrypt.</param>
      /// <param name="provider">The cryptographic provider to use for encrypting.</param>
      /// <returns>Plaintext stream ready to be read.</returns>
      public static Stream GetDecryptedStream(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 input and output streams
         CryptoStream decryptStream = new CryptoStream(inStream, provider.CreateDecryptor(), CryptoStreamMode.Read);
         MemoryStream outStream = new MemoryStream();
         
         // Read the stream and write it to the output. 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 = decryptStream.Read(inputBytes, 0, inputBytes.Length)) != 0) 
         {
            outStream.Write(inputBytes, 0, numBytes);
         }

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

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