// Encrypts the given element with the certificate specified. The certificate is added as
// an X509Data KeyInfo to an EncryptedKey (AES session key) generated randomly.
public EncryptedData Encrypt(XmlElement inputElement, X509Certificate2 certificate)
{
if (inputElement == null)
{
throw new ArgumentNullException(nameof(inputElement));
}
if (certificate == null)
{
throw new ArgumentNullException(nameof(certificate));
}
using (RSA rsaPublicKey = certificate.GetRSAPublicKey())
{
if (rsaPublicKey == null)
{
throw new NotSupportedException(SR.NotSupported_KeyAlgorithm);
}
// Create the EncryptedData object, using an AES-256 session key by default.
EncryptedData ed = new EncryptedData();
ed.Type = EncryptedXml.XmlEncElementUrl;
ed.EncryptionMethod = new EncryptionMethod(EncryptedXml.XmlEncAES256Url);
// Include the certificate in the EncryptedKey KeyInfo.
EncryptedKey ek = new EncryptedKey();
ek.EncryptionMethod = new EncryptionMethod(EncryptedXml.XmlEncRSA15Url);
ek.KeyInfo.AddClause(new KeyInfoX509Data(certificate));
// Create a random AES session key and encrypt it with the public key associated with the certificate.
RijndaelManaged rijn = new RijndaelManaged();
ek.CipherData.CipherValue = EncryptedXml.EncryptKey(rijn.Key, rsaPublicKey, false);
// Encrypt the input element with the random session key that we've created above.
KeyInfoEncryptedKey kek = new KeyInfoEncryptedKey(ek);
ed.KeyInfo.AddClause(kek);
ed.CipherData.CipherValue = EncryptData(inputElement, rijn, false);
return(ed);
}
}
// Encrypts the given element with the key name specified. A corresponding key name mapping
// has to be defined before calling this method. The key name is added as
// a KeyNameInfo KeyInfo to an EncryptedKey (AES session key) generated randomly.
public EncryptedData Encrypt(XmlElement inputElement, string keyName)
{
if (inputElement == null)
{
throw new ArgumentNullException(nameof(inputElement));
}
if (keyName == null)
{
throw new ArgumentNullException(nameof(keyName));
}
object encryptionKey = null;
if (_keyNameMapping != null)
{
encryptionKey = _keyNameMapping[keyName];
}
if (encryptionKey == null)
{
throw new CryptographicException(SR.Cryptography_Xml_MissingEncryptionKey);
}
// kek is either a SymmetricAlgorithm or an RSA key, otherwise, we wouldn't be able to insert it in the hash table
SymmetricAlgorithm symKey = encryptionKey as SymmetricAlgorithm;
RSA rsa = encryptionKey as RSA;
// Create the EncryptedData object, using an AES-256 session key by default.
EncryptedData ed = new EncryptedData();
ed.Type = EncryptedXml.XmlEncElementUrl;
ed.EncryptionMethod = new EncryptionMethod(EncryptedXml.XmlEncAES256Url);
// Include the key name in the EncryptedKey KeyInfo.
string encryptionMethod = null;
if (symKey == null)
{
encryptionMethod = EncryptedXml.XmlEncRSA15Url;
}
else if (symKey is TripleDES)
{
// CMS Triple DES Key Wrap
encryptionMethod = EncryptedXml.XmlEncTripleDESKeyWrapUrl;
}
else if (symKey is Rijndael || symKey is Aes)
{
// FIPS AES Key Wrap
switch (symKey.KeySize)
{
case 128:
encryptionMethod = EncryptedXml.XmlEncAES128KeyWrapUrl;
break;
case 192:
encryptionMethod = EncryptedXml.XmlEncAES192KeyWrapUrl;
break;
case 256:
encryptionMethod = EncryptedXml.XmlEncAES256KeyWrapUrl;
break;
}
}
else
{
// throw an exception if the transform is not in the previous categories
throw new CryptographicException(SR.Cryptography_Xml_NotSupportedCryptographicTransform);
}
EncryptedKey ek = new EncryptedKey();
ek.EncryptionMethod = new EncryptionMethod(encryptionMethod);
ek.KeyInfo.AddClause(new KeyInfoName(keyName));
// Create a random AES session key and encrypt it with the public key associated with the certificate.
RijndaelManaged rijn = new RijndaelManaged();
ek.CipherData.CipherValue = (symKey == null ? EncryptedXml.EncryptKey(rijn.Key, rsa, false) : EncryptedXml.EncryptKey(rijn.Key, symKey));
// Encrypt the input element with the random session key that we've created above.
KeyInfoEncryptedKey kek = new KeyInfoEncryptedKey(ek);
ed.KeyInfo.AddClause(kek);
ed.CipherData.CipherValue = EncryptData(inputElement, rijn, false);
return(ed);
}
