private SymmetricAlgorithm DecryptEncryptedKeyClass(EncryptedKey encryptedKey, string symmetricAlgorithmUri)
{
if (encryptedKey == null)
{
throw ExceptionUtility.ArgumentNull(nameof(encryptedKey));
}
SymmetricAlgorithm decryptionKey = null;
if (encryptedKey.KeyInfo != null)
{
foreach (var keyInfo in encryptedKey.KeyInfo)
{
// Извлечение ключа по имени
if (keyInfo is KeyInfoName)
{
var keyName = ((KeyInfoName)keyInfo).Value;
var keyAlgorithm = this.GetKeyNameMapping()[keyName];
if (keyAlgorithm != null)
{
if (keyAlgorithm is SymmetricAlgorithm)
{
decryptionKey = DecryptKeyClass(encryptedKey.CipherData.CipherValue, (SymmetricAlgorithm)keyAlgorithm, symmetricAlgorithmUri, encryptedKey.EncryptionMethod.KeyAlgorithm);
}
else if (keyAlgorithm is RSA)
{
var useOaep = (encryptedKey.EncryptionMethod != null) && (encryptedKey.EncryptionMethod.KeyAlgorithm == XmlEncRSAOAEPUrl);
decryptionKey = DecryptKeyClass(encryptedKey.CipherData.CipherValue, (RSA)keyAlgorithm, useOaep, symmetricAlgorithmUri);
}
else if (keyAlgorithm is GostAsymmetricAlgorithm)
{
decryptionKey = DecryptKeyClass(encryptedKey.CipherData.CipherValue, (GostAsymmetricAlgorithm)keyAlgorithm);
}
}
break;
}
// Извлечение ключа из сертификата
if (keyInfo is KeyInfoX509Data)
{
var certificates = CryptographyXmlUtils.BuildBagOfCertsDecryption((KeyInfoX509Data)keyInfo);
foreach (var certificate in certificates)
{
var privateKey = certificate.GetPrivateKeyAlgorithm();
if (privateKey is RSA)
{
var useOaep = (encryptedKey.EncryptionMethod != null) && (encryptedKey.EncryptionMethod.KeyAlgorithm == XmlEncRSAOAEPUrl);
decryptionKey = DecryptKeyClass(encryptedKey.CipherData.CipherValue, (RSA)privateKey, useOaep, symmetricAlgorithmUri);
}
else if (privateKey is GostAsymmetricAlgorithm)
{
decryptionKey = DecryptKeyClass(encryptedKey.CipherData.CipherValue, (GostAsymmetricAlgorithm)privateKey);
}
}
break;
}
// Извлечение ключа по ссылке
if (keyInfo is KeyInfoRetrievalMethod)
{
var idValue = CryptographyXmlUtils.ExtractIdFromLocalUri(((KeyInfoRetrievalMethod)keyInfo).Uri);
var idElement = GetIdElement(this.GetDocument(), idValue);
if (idElement != null)
{
var secondEncryptedKey = new EncryptedKey();
secondEncryptedKey.LoadXml(idElement);
decryptionKey = DecryptEncryptedKeyClass(secondEncryptedKey, symmetricAlgorithmUri);
}
break;
}
// Ключ в готовом виде
if (keyInfo is KeyInfoEncryptedKey)
{
var secondEncryptedKey = ((KeyInfoEncryptedKey)keyInfo).EncryptedKey;
var symmetricAlgorithm = DecryptEncryptedKeyClass(secondEncryptedKey, symmetricAlgorithmUri);
if (symmetricAlgorithm != null)
{
decryptionKey = DecryptKeyClass(encryptedKey.CipherData.CipherValue, symmetricAlgorithm, symmetricAlgorithmUri, encryptedKey.EncryptionMethod.KeyAlgorithm);
}
break;
}
}
}
return(decryptionKey);
}
public override SymmetricAlgorithm GetDecryptionKey(EncryptedData encryptedData, string symmetricAlgorithmUri)
{
if (encryptedData == null)
{
throw ExceptionUtility.ArgumentNull(nameof(encryptedData));
}
SymmetricAlgorithm decryptionKey = null;
if (encryptedData.KeyInfo != null)
{
EncryptedKey encryptedKey = null;
foreach (var keyInfo in encryptedData.KeyInfo)
{
// Извлечение ключа по имени
if (keyInfo is KeyInfoName)
{
var keyName = ((KeyInfoName)keyInfo).Value;
var keyAlgorithm = this.GetKeyNameMapping()[keyName];
if (keyAlgorithm == null)
{
var nsManager = new XmlNamespaceManager(this.GetDocument().NameTable);
nsManager.AddNamespace("enc", XmlEncNamespaceUrl);
var encryptedKeyNodes = this.GetDocument().SelectNodes("//enc:EncryptedKey", nsManager);
if (encryptedKeyNodes != null)
{
foreach (XmlElement encryptedKeyNode in encryptedKeyNodes)
{
var currentEncryptedKey = new EncryptedKey();
currentEncryptedKey.LoadXml(encryptedKeyNode);
if ((currentEncryptedKey.CarriedKeyName == keyName) && (currentEncryptedKey.Recipient == Recipient))
{
encryptedKey = currentEncryptedKey;
break;
}
}
}
}
else
{
decryptionKey = (SymmetricAlgorithm)keyAlgorithm;
}
break;
}
// Извлечение ключа по ссылке
if (keyInfo is KeyInfoRetrievalMethod)
{
var idValue = CryptographyXmlUtils.ExtractIdFromLocalUri(((KeyInfoRetrievalMethod)keyInfo).Uri);
var idElement = GetIdElement(this.GetDocument(), idValue);
if (idElement != null)
{
encryptedKey = new EncryptedKey();
encryptedKey.LoadXml(idElement);
}
break;
}
// Ключ в готовом виде
if (keyInfo is KeyInfoEncryptedKey)
{
encryptedKey = ((KeyInfoEncryptedKey)keyInfo).EncryptedKey;
break;
}
}
if (decryptionKey == null && encryptedKey != null)
{
if (symmetricAlgorithmUri == null)
{
if (encryptedData.EncryptionMethod == null)
{
throw ExceptionUtility.CryptographicException(Resources.XmlMissingAlgorithm);
}
symmetricAlgorithmUri = encryptedData.EncryptionMethod.KeyAlgorithm;
}
decryptionKey = DecryptEncryptedKeyClass(encryptedKey, symmetricAlgorithmUri);
}
}
return(decryptionKey);
}