This property contains a key for signing/verification.
This property contains a key, used for signing of XML data. If SignatureMethodType is set to smtMAC, then only an object of type TElXMLKeyInfoHMACData can be used. If SignatureMethodType is set to smtSig, then only keypairs of the public-key based algorithms (descendants of TElXMLKeyInfoAsymmetricData type) can be used. Also, in case of smtSig, KeyData must contain both private and public keys, in order to perform signing.