/// <summary>
/// Deserialize from the XML representation.
/// </summary>
/// <remarks>
/// Based upon https://www.w3.org/TR/xmldsig-core/#sec-DSAKeyValue.
/// </remarks>
/// <param name="value">
/// An <see cref="XmlElement"/> containing the XML representation. This cannot be null.
/// </param>
/// <exception cref="ArgumentNullException">
/// <paramref name="value"/> cannot be null.
/// </exception>
/// <exception cref="CryptographicException">
/// The XML has the incorrect schema or the DSA parameters are invalid.
/// </exception>
public override void LoadXml(XmlElement value)
{
if (value == null)
{
throw new ArgumentNullException("value");
}
if (value.Name != KeyValueElementName ||
value.NamespaceURI != SignedXml.XmlDsigNamespaceUrl)
{
throw new System.Security.Cryptography.CryptographicException(String.Format("Root element must be {KeyValueElementName} element in namepsace {SignedXml.XmlDsigNamespaceUrl}"));
}
const string xmlDsigNamespacePrefix = "dsig";
XmlNamespaceManager xmlNamespaceManager = new XmlNamespaceManager(value.OwnerDocument.NameTable);
xmlNamespaceManager.AddNamespace(xmlDsigNamespacePrefix, SignedXml.XmlDsigNamespaceUrl);
XmlNode dsaKeyValueElement = value.SelectSingleNode(String.Format("{xmlDsigNamespacePrefix}:{DSAKeyValueElementName}"), xmlNamespaceManager);
if (dsaKeyValueElement == null)
{
throw new System.Security.Cryptography.CryptographicException(String.Format("{KeyValueElementName} must contain child element {DSAKeyValueElementName}"));
}
XmlNode yNode = dsaKeyValueElement.SelectSingleNode(String.Format("{xmlDsigNamespacePrefix}:{YElementName}"), xmlNamespaceManager);
if (yNode == null)
{
throw new System.Security.Cryptography.CryptographicException(String.Format("{YElementName} is missing"));
}
XmlNode pNode = dsaKeyValueElement.SelectSingleNode(String.Format("{xmlDsigNamespacePrefix}:{PElementName}"), xmlNamespaceManager);
XmlNode qNode = dsaKeyValueElement.SelectSingleNode(String.Format("{xmlDsigNamespacePrefix}:{QElementName}"), xmlNamespaceManager);
if ((pNode == null && qNode != null) || (pNode != null && qNode == null))
{
throw new System.Security.Cryptography.CryptographicException(String.Format("{PElementName} and {QElementName} can only occour in combination"));
}
XmlNode gNode = dsaKeyValueElement.SelectSingleNode(String.Format("{xmlDsigNamespacePrefix}:{GElementName}"), xmlNamespaceManager);
XmlNode jNode = dsaKeyValueElement.SelectSingleNode(String.Format("{xmlDsigNamespacePrefix}:{JElementName}"), xmlNamespaceManager);
XmlNode seedNode = dsaKeyValueElement.SelectSingleNode(String.Format("{xmlDsigNamespacePrefix}:{SeedElementName}"), xmlNamespaceManager);
XmlNode pgenCounterNode = dsaKeyValueElement.SelectSingleNode(String.Format("{xmlDsigNamespacePrefix}:{PgenCounterElementName}"), xmlNamespaceManager);
if ((seedNode == null && pgenCounterNode != null) || (seedNode != null && pgenCounterNode == null))
{
throw new System.Security.Cryptography.CryptographicException(String.Format("{SeedElementName} and {PgenCounterElementName} can only occur in combination"));
}
try
{
_key = new DsaPublicKeyParameters(new Math.BigInteger(Convert.FromBase64String(yNode.InnerText)),
new DsaParameters(
new Math.BigInteger((pNode != null) ? Convert.FromBase64String(pNode.InnerText) : null),
new Math.BigInteger((qNode != null) ? Convert.FromBase64String(qNode.InnerText) : null),
new Math.BigInteger((gNode != null) ? Convert.FromBase64String(gNode.InnerText) : null),
new DsaValidationParameters(
(seedNode != null) ? Convert.FromBase64String(seedNode.InnerText) : null,
(pgenCounterNode != null) ? Utils.ConvertByteArrayToInt(Convert.FromBase64String(pgenCounterNode.InnerText)) : 0)));
}
catch (Exception ex)
{
throw new System.Security.Cryptography.CryptographicException("An error occurred parsing the key components", ex);
}
}
