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2010-05-26T15:31:19Z

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2010-05-26T11:45:37Z

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==Illustrates asymmetric cryptography==

<source lang="csharp">
/*
Mastering Visual C# .NET
by Jason Price, Mike Gunderloy
Publisher: Sybex;
ISBN: 0782129110
*/
/*
Example19_11.cs illustrates asymmetric cryptography
*/
using System;
using System.IO;
using System.Security.Cryptography;
public class Example19_11
{
public static void Main()
{
// Create a new crypto provider
RSACryptoServiceProvider rsa =
new RSACryptoServiceProvider();
// Data to encrypt
Byte[] testData = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
// Encrypt the data
Byte[] encryptedData = rsa.Encrypt(testData, false);
Console.WriteLine("Encrypted data:");
for(int i=0; i<encryptedData.GetLength(0); i++)
{
Console.Write("{0} ", encryptedData[i]);
}
Console.WriteLine();
// Decrypt the data
Byte[] decryptedData = rsa.Decrypt(encryptedData, false);
Console.WriteLine("Decrypted Data:");
for(int i=0; i<decryptedData.GetLength(0); i++)
{
Console.Write("{0} ", decryptedData[i]);
}
Console.WriteLine();
}
}

</source>

==Illustrates declarative role-based security==

<source lang="csharp">
/*
Mastering Visual C# .NET
by Jason Price, Mike Gunderloy
Publisher: Sybex;
ISBN: 0782129110
*/

/*
Example19_8.cs illustrates declarative role-based security
*/
using System;
using System.IO;
using System.Security.Permissions;
[PrincipalPermissionAttribute(SecurityAction.Demand, Role="Administrators")]
public class Example19_8
{
public static void Main()
{
// Create a new file to work with
FileStream fsOut = File.Create(@"c:\\temp\\test.txt");
// Create a StreamWriter to handle writing
StreamWriter sw = new StreamWriter(fsOut);
// And write some data
sw.WriteLine(""Twas brillig, and the slithy toves");
sw.WriteLine("Did gyre and gimble in the wabe.");
sw.Flush();
sw.Close();
}
}

</source>

==Illustrates decrypting a file==

<source lang="csharp">
/*
Mastering Visual C# .NET
by Jason Price, Mike Gunderloy
Publisher: Sybex;
ISBN: 0782129110
*/
/*
Example19_10.cs illustrates decrypting a file
*/
using System;
using System.IO;
using System.Security.Cryptography;
public class Example19_10
{
public static void Main()
{
// Create a new crypto provider
TripleDESCryptoServiceProvider tdes =
new TripleDESCryptoServiceProvider();
// open the file containing the key and IV
FileStream fsKeyIn = File.OpenRead(@"c:\temp\encrypted.key");

// use a BinaryReader to read formatted data from the file
BinaryReader br = new BinaryReader(fsKeyIn);
// read data from the file and close it
tdes.Key = br.ReadBytes(24);
tdes.IV = br.ReadBytes(8);
// Open the encrypted file
FileStream fsIn = File.OpenRead(@"c:\\temp\\encrypted.txt");
// Create a cryptostream to decrypt from the filestream
CryptoStream cs = new CryptoStream(fsIn, tdes.CreateDecryptor(),
CryptoStreamMode.Read);
// Create a StreamReader to format the input
StreamReader sr = new StreamReader(cs);
// And decrypt the data
Console.WriteLine(sr.ReadToEnd());
sr.Close();
}
}

</source>

==Illustrates demanding permissions==

<source lang="csharp">
/*
Mastering Visual C# .NET
by Jason Price, Mike Gunderloy
Publisher: Sybex;
ISBN: 0782129110
*/
/*
Example19_5.cs illustrates demanding permissions
*/
using System;
using System.IO;
using System.Security.Permissions;
[FileIOPermissionAttribute(SecurityAction.Demand,
All=@"c:\\temp")]
public class Example19_5
{
public static void MakeFile()
{
// Create a new file to work with
FileStream fsOut = File.Create(@"c:\\temp\\test.txt");
// Create a StreamWriter to handle writing
StreamWriter sw = new StreamWriter(fsOut);
// And write some data
sw.WriteLine(""Twas brillig, and the slithy toves");
sw.WriteLine("Did gyre and gimble in the wabe.");
sw.Flush();
sw.Close();
}
}

</source>

==Illustrates encrypting a file==

<source lang="csharp">
/*
Mastering Visual C# .NET
by Jason Price, Mike Gunderloy
Publisher: Sybex;
ISBN: 0782129110
*/
/*
Example19_9.cs illustrates encrypting a file
*/
using System;
using System.IO;
using System.Security.Cryptography;
public class Example19_9
{
public static void Main()
{
// Create a new file to work with
FileStream fsOut = File.Create(@"c:\temp\encrypted.txt");
// Create a new crypto provider
TripleDESCryptoServiceProvider tdes =
new TripleDESCryptoServiceProvider();
// Create a cryptostream to encrypt to the filestream
CryptoStream cs = new CryptoStream(fsOut, tdes.CreateEncryptor(),
CryptoStreamMode.Write);
// Create a StreamWriter to format the output
StreamWriter sw = new StreamWriter(cs);
// And write some data
sw.WriteLine(""Twas brillig, and the slithy toves");
sw.WriteLine("Did gyre and gimble in the wabe.");
sw.Flush();
sw.Close();
// save the key and IV for future use
FileStream fsKeyOut = File.Create(@"c:\\temp\encrypted.key");

// use a BinaryWriter to write formatted data to the file
BinaryWriter bw = new BinaryWriter(fsKeyOut);
// write data to the file
bw.Write( tdes.Key );
bw.Write( tdes.IV );
// flush and close
bw.Flush();
bw.Close();
}
}

</source>

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