Monday, October 01, 2007

How to generate RSA public and private keys as well as export to XML

The following method shows how RSA keys can be saved to disk as an XML file. The XML files can then be used to make an RSA secure channel -- the public key is used for encryption and the private one for decryption.

///
/// Generates 2 XML files (public and private key)
///

/// RSA private key file path
/// RSA private key file path
/// secure size must be above 512
public static void GenerateRsa(string privateKeyPath, string publicKeyPath, int size)
{
//stream to save the keys
FileStream fs = null;
StreamWriter sw = null;
//create RSA provider
RSACryptoServiceProvider rsa = new RSACryptoServiceProvider(size);
try
{
//save private key
fs = new FileStream(privateKeyPath, FileMode.Create, FileAccess.Write);
sw = new StreamWriter(fs);
sw.Write(rsa.ToXmlString(true));
sw.Flush();
}
finally
{
if (sw != null) sw.Close();
if (fs != null) fs.Close();
}
try
{
//save public key
fs = new FileStream(publicKeyPath, FileMode.Create, FileAccess.Write);
sw = new StreamWriter(fs);
sw.Write(rsa.ToXmlString(false));
sw.Flush();
}
finally
{
if (sw != null) sw.Close();
if (fs != null) fs.Close();
}
rsa.Clear();
}

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