There is a fantastic example in codeproject to Encrypt and decrypt data using Cryptography namespace. Unfortunately I could not make the downloaded code worked. That is why I copy the code from the site and build a console application.
1. Create a class for Cryptography.
classSymmCrypto
{
///<remarks>
/// Supported .Net intrinsic SymmetricAlgorithm classes.
///</remarks>
publicenumSymmProvEnum : int
{
DES, RC2, Rijndael
}
privateSymmetricAlgorithm mobjCryptoService;
///<remarks>
/// Constructor for using an intrinsic .Net SymmetricAlgorithm class.
///</remarks>
public SymmCrypto(SymmProvEnum NetSelected)
{
switch (NetSelected)
{
caseSymmProvEnum.DES:
mobjCryptoService = newDESCryptoServiceProvider();
break;
caseSymmProvEnum.RC2:
mobjCryptoService = newRC2CryptoServiceProvider();
break;
caseSymmProvEnum.Rijndael:
mobjCryptoService = newRijndaelManaged();
break;
}
}
///<remarks>
/// Constructor for using a customized SymmetricAlgorithm class.
///</remarks>
public SymmCrypto(SymmetricAlgorithm ServiceProvider)
{
mobjCryptoService = ServiceProvider;
}
///<remarks>
/// Depending on the legal key size limitations of a specific CryptoService provider
/// and length of the private key provided, padding the secret key with space character
/// to meet the legal size of the algorithm.
///</remarks>
privatebyte[] GetLegalKey(string Key)
{
string sTemp;
if (mobjCryptoService.LegalKeySizes.Length > 0)
{
int lessSize = 0, moreSize = mobjCryptoService.LegalKeySizes[0].MinSize;
// key sizes are in bits
while (Key.Length * 8 > moreSize)
{
lessSize = moreSize;
moreSize += mobjCryptoService.LegalKeySizes[0].SkipSize;
}
sTemp = Key.PadRight(moreSize / 8, ‘ ‘);
}
else
sTemp = Key;
// convert the secret key to byte array
returnASCIIEncoding.ASCII.GetBytes(sTemp);
}
publicstring Encrypting(string Source, string Key)
{
byte[] bytIn = System.Text.ASCIIEncoding.ASCII.GetBytes(Source);
// create a MemoryStream so that the process can be done without I/O files
System.IO.MemoryStream ms = new System.IO.MemoryStream();
byte[] bytKey = GetLegalKey(Key);
// set the private key
mobjCryptoService.Key = bytKey;
mobjCryptoService.IV = bytKey;
// create an Encryptor from the Provider Service instance
ICryptoTransform encrypto = mobjCryptoService.CreateEncryptor();
// create Crypto Stream that transforms a stream using the encryption
CryptoStream cs = newCryptoStream(ms, encrypto, CryptoStreamMode.Write);
// write out encrypted content into MemoryStream
cs.Write(bytIn, 0, bytIn.Length);
cs.FlushFinalBlock();
// get the output and trim the ” bytes
byte[] bytOut = ms.GetBuffer();
int i = 0;
for (i = 0; i < bytOut.Length; i++)
if (bytOut[i] == 0)
break;
// convert into Base64 so that the result can be used in xml
return System.Convert.ToBase64String(bytOut, 0, i);
}
publicstring Decrypting(string Source, string Key)
{
// convert from Base64 to binary
byte[] bytIn = System.Convert.FromBase64String(Source);
// create a MemoryStream with the input
System.IO.MemoryStream ms = new System.IO.MemoryStream(bytIn, 0, bytIn.Length);
byte[] bytKey = GetLegalKey(Key);
// set the private key
mobjCryptoService.Key = bytKey;
mobjCryptoService.IV = bytKey;
// create a Decryptor from the Provider Service instance
ICryptoTransform encrypto = mobjCryptoService.CreateDecryptor();
// create Crypto Stream that transforms a stream using the decryption
CryptoStream cs = newCryptoStream(ms, encrypto, CryptoStreamMode.Read);
// read out the result from the Crypto Stream
System.IO.StreamReader sr = new System.IO.StreamReader(cs);
return sr.ReadToEnd();
}
}
2. Type the code in the main program as follow.
staticvoid Main(string[] args)
{
SymmCrypto sc = newSymmCrypto(ConAppCryptography.SymmCrypto.SymmProvEnum.DES);
string hello = sc.Encrypting(“Hello world”, “Hello”);
Console.WriteLine(hello);
Console.WriteLine(“=============================================================================”);
hello = sc.Decrypting(hello, “Hello”);
Console.WriteLine(hello);
//http://www.codeproject.com/Articles/1967/Encryption-Decryption-with-NET
}
You can also download a single solution from http://skydrive.live.com. The sample file name is ConAppCryptography.rar My MSN ID is chanmmn@hotmail.com.
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