This is the soap envelope:

<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"><soap:Header><Action xmlns="http://www.w3.org/2005/08/addressing">urn:sap-com:document:sap:rfc:functions:SRT_TEST_STATELESS:SRT_TEST_STATELESSRequest</Action><MessageID xmlns="http://www.w3.org/2005/08/addressing">urn:uuid:ae1fc1ce-1143-4895-a4cf-c6160f165d25</MessageID><To xmlns="http://www.w3.org/2005/08/addressing">https://sapadx01.generali.it/sap/bc/srt/rfc/sap/srt_test_stateless/700/srt_test_stateless_saml2/srt_test_stateless_saml2</To><ReplyTo xmlns="http://www.w3.org/2005/08/addressing"><Address>http://www.w3.org/2005/08/addressing/anonymous</Address></ReplyTo><wsse:Security xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd" xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd" soap:mustUnderstand="1"><wsu:Timestamp wsu:Id="TS-2"><wsu:Created>2013-05-23T13:54:34.958Z</wsu:Created><wsu:Expires>2013-05-23T13:59:34.958Z</wsu:Expires></wsu:Timestamp><saml:Assertion xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion" ID="ID_2107d9c4-cf0f-402d-9287-8c90816a1825" IssueInstant="2013-05-23T13:54:34.814Z" Version="2.0"><saml:Issuer xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion">PicketLinkSTS</saml:Issuer><dsig:Signature xmlns:dsig="http://www.w3.org/2000/09/xmldsig#"><dsig:SignedInfo xmlns:dsig="http://www.w3.org/2000/09/xmldsig#"><dsig:CanonicalizationMethod xmlns:dsig="http://www.w3.org/2000/09/xmldsig#" Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#WithComments"/><dsig:SignatureMethod xmlns:dsig="http://www.w3.org/2000/09/xmldsig#" Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1"/><dsig:Reference xmlns:dsig="http://www.w3.org/2000/09/xmldsig#" URI="#ID_2107d9c4-cf0f-402d-9287-8c90816a1825"><dsig:Transforms xmlns:dsig="http://www.w3.org/2000/09/xmldsig#"><dsig:Transform xmlns:dsig="http://www.w3.org/2000/09/xmldsig#" Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"/><dsig:Transform xmlns:dsig="http://www.w3.org/2000/09/xmldsig#" Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/></dsig:Transforms><dsig:DigestMethod xmlns:dsig="http://www.w3.org/2000/09/xmldsig#" Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/><dsig:DigestValue xmlns:dsig="http://www.w3.org/2000/09/xmldsig#">gxeiRp3twSZTduS3Glz+f6FjguM=</dsig:DigestValue></dsig:Reference></dsig:SignedInfo><dsig:SignatureValue xmlns:dsig="http://www.w3.org/2000/09/xmldsig#">ceJ2p9kC77FOy46HIVFNtxYBH5rQWFY7CEiUJgt33+GS/mQ1ny/Z/2/TY9b1lgeLZLObjW5Y5uCZEP6l1Ttz2XIgWfzXGu5qI6O9D5Qngx5zzZgZEKL4aOJaqxm6pGIXQIEJkQw/+z9/rbwFIs8mw4SdIk+Eo5g33siHn+WsFVh+BxTxW4ixweWTMj85SanXxC3z0wlXYgJNGfEjEeUaocBgroQC4Ww8nv4N+0UImfdlKV7s75nZZgrmFXyP+vB9Z1EucveOnCyg8AcFzxq+V+mfnjHIUDAHmpCoMCRXCis871igvQ2gi/vb5NFcJcuEAtx770YoG/ZMvuGvmT7qSw==</dsig:SignatureValue><dsig:KeyInfo xmlns:dsig="http://www.w3.org/2000/09/xmldsig#"><dsig:X509Data xmlns:dsig="http://www.w3.org/2000/09/xmldsig#"><dsig:X509Certificate xmlns:dsig="http://www.w3.org/2000/09/xmldsig#">MIIGhDCCBWygAwIBAgIKWXKzygAAAAACZzANBgkqhkiG9w0BAQUFADBmMRMwEQYKCZImiZPyLGQBGRYDbmV0MRgwFgYKCZImiZPyLGQBGRYIZ2VuZXJhbGkxFDASBgoJkiaJk/IsZAEZFgRjb3JwMR8wHQYDVQQDExZHRU5FUkFMSS1JbnRlcm5hbEVOVENBMB4XDTEzMDUwNjEyNTMzOFoXDTE1MDUwNjEyNTMzOFowga8xCzAJBgNVBAYTAklUMRAwDgYDVQQIEwdUcmV2aXNvMRgwFgYDVQQHEw9Nb2dsaWFubyBWZW5ldG8xJjAkBgNVBAoTHUFzc2ljdXJhemlvbmkgR2VuZXJhbGkgUy5wLkEuMS0wKwYDVQQLEyRHZW5lcmFsaSBCdXNpbmVzcyBTb2x1dGlvbnMgUy5DLnAuQS4xHTAbBgNVBAMTFHN0c2hjczAxLmdlbmVyYWxpLml0MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAjMHsMBAQPU9bPQjrgys2qmppLMkCNKKeCwvIFfHtWp4n0/jV6QHegThXm+mYpLY+6rNl26ifWddDFOBPtcKtXKAa834AHU1mT/XJX59eNfin80TRaIoNotbZIMam3/Pok3PUw1klDzD/k+6ofcLywlLcCHIXhesR90VLxSrKiwt+DJB5nzQFISE9rX0xXfHXtQ5h6wUm9a3E5ZLw9b/B6laVT9lUgURmx1QMtZFO3+DYZx0uUQsftBcD+Nf57rOHBndoQntm6EO1dA61diaZYP0trrcxjjCBSyFjFa9LkeHc3+2ed+dFKHhd+pmIPQOC4guRUR61SP3342ESsvBuYwIDAQABo4IC6DCCAuQwHQYDVR0OBBYEFDwdzeLTgT1UWkI94BVpyI65dxxpMB8GA1UdIwQYMBaAFNDkZ+qBOaM5xF162+E8/VH/GI72MIIBEwYDVR0fBIIBCjCCAQYwggECoIH/oIH8hoHCbGRhcDovLy9DTj1HRU5FUkFMSS1JbnRlcm5hbEVOVENBLENOPUQzRU5UQ0FUVjAxLENOPUNEUCxDTj1QdWJsaWMlMjBLZXklMjBTZXJ2aWNlcyxDTj1TZXJ2aWNlcyxDTj1Db25maWd1cmF0aW9uLERDPWdlbmVyYWxpLERDPW5ldD9jZXJ0aWZpY2F0ZVJldm9jYXRpb25MaXN0P2Jhc2U/b2JqZWN0Q2xhc3M9Y1JMRGlzdHJpYnV0aW9uUG9pbnSGNWh0dHA6Ly9wa2kuZ2VuZXJhbGkuaXQvQ0RQL0dFTkVSQUxJLUludGVybmFsRU5UQ0EuY3JsMIIBDAYIKwYBBQUHAQEEgf8wgfwwgbYGCCsGAQUFBzAChoGpbGRhcDovLy9DTj1HRU5FUkFMSS1JbnRlcm5hbEVOVENBLENOPUFJQSxDTj1QdWJsaWMlMjBLZXklMjBTZXJ2aWNlcyxDTj1TZXJ2aWNlcyxDTj1Db25maWd1cmF0aW9uLERDPWdlbmVyYWxpLERDPW5ldD9jQUNlcnRpZmljYXRlP2Jhc2U/b2JqZWN0Q2xhc3M9Y2VydGlmaWNhdGlvbkF1dGhvcml0eTBBBggrBgEFBQcwAoY1aHR0cDovL3BraS5nZW5lcmFsaS5pdC9BSUEvR0VORVJBTEktSW50ZXJuYWxFTlRDQS5jcnQwCwYDVR0PBAQDAgWgMDwGCSsGAQQBgjcVBwQvMC0GJSsGAQQBgjcVCIeLhCSm3C6G8Zkgh9LcA4brzn9UhajTSoXF4R8CAWQCAQQwEwYDVR0lBAwwCgYIKwYBBQUHAwEwGwYJKwYBBAGCNxUKBA4wDDAKBggrBgEFBQcDATANBgkqhkiG9w0BAQUFAAOCAQEANpfYnc1M4Ya2z0OKfRwpVnXWvWVEnZKh7oskSxrz9b8hCKma+/ChHxHkc+PpPPKymZwTsWL0AY/5GGAz1U8LzjuCBgSWgu+NheJYM9WJeu4POxG1Jbv5VXCwQ/e/oIZf+6zkmlntU/tTliKuDqoVRvXn9yRNj9Wbyj351T6Jd9TVIpJ8fNt4lQ9I5Fp7YfqhrsR15TpXrhOFAc6lK1TcY4rT0UMUx61udR+kliRjgwaMwZMolUoUApFsX1H2UvivvIpsqQVlaW+xllkJVIBuHQHkkv5k9MwFOl36GF3//UnHj99y0CiwNDDb9KdXyU2u4pnWG5HVYNvz+MvrB3P3kg==</dsig:X509Certificate></dsig:X509Data></dsig:KeyInfo></dsig:Signature><saml:Subject xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion"><saml:NameID xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion" Format="urn:oasis:names:tc:SAML:1.1:nameid-format:unspecified">POLONI</saml:NameID><saml:SubjectConfirmation xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion" Method="urn:oasis:names:tc:SAML:2.0:cm:holder-of-key"><saml:SubjectConfirmationData xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion"><ds:KeyInfo xmlns:ds="http://www.w3.org/2000/09/xmldsig#"><xenc:EncryptedKey xmlns:xenc="http://www.w3.org/2001/04/xmlenc#"><xenc:EncryptionMethod xmlns:xenc="http://www.w3.org/2001/04/xmlenc#" Algorithm="http://www.w3.org/2001/04/xmlenc#rsa-1_5"/><ds:KeyInfo xmlns:ds="http://www.w3.org/2000/09/xmldsig#"><ds:X509Data xmlns:ds="http://www.w3.org/2000/09/xmldsig#"><ds:X509IssuerSerial xmlns:ds="http://www.w3.org/2000/09/xmldsig#"><ds:X509IssuerName xmlns:ds="http://www.w3.org/2000/09/xmldsig#">CN=GENERALI-InternalENTCA, DC=corp, DC=generali, DC=net</ds:X509IssuerName><ds:X509SerialNumber xmlns:ds="http://www.w3.org/2000/09/xmldsig#">521626961400866690564724</ds:X509SerialNumber></ds:X509IssuerSerial></ds:X509Data></ds:KeyInfo><xenc:CipherData xmlns:xenc="http://www.w3.org/2001/04/xmlenc#"><xenc:CipherValue xmlns:xenc="http://www.w3.org/2001/04/xmlenc#">bnFodGBPEbyRqIu3p+sI10pWnSTL4kxPkZy/FrofP5ZGznMsy8tHlYc8G0cwKJIHuryD769nKve8qnQkWFTnzN8H5rqUyzhsJ9FXyW+7IdiKCbsvDKQNiU6e8tbLjaGik4EYHlKoU3xwUIE0DbC8PuDvcgJPtaru/reoAplL+AOV7ZKt5StdJtPs6fy4rWsYnT0C41LnnxJ7O//PQ+42iUDn+wURCMTL+0b1bXi7Q8v1mVlkdRh9vhyNk9gaRff6RacqknzQ4MNsadUdpcCDoDttSvsfqr2CP6uO54NfsvJt8PPn+/HzH0ImJjbzPgRsEoAmhBhGM1cehjgSAdEQxg==</xenc:CipherValue></xenc:CipherData></xenc:EncryptedKey></ds:KeyInfo></saml:SubjectConfirmationData></saml:SubjectConfirmation></saml:Subject><saml:Conditions xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion" NotBefore="2013-05-23T13:54:34.814Z" NotOnOrAfter="2013-05-23T15:54:34.814Z"><saml:AudienceRestriction xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion"><saml:Audience xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion">https://sapadx01.generali.it/sap/bc/srt/rfc/sap/srt_test_stateless/700/srt_test_stateless_saml2/srt_test_stateless_saml2</saml:Audience></saml:AudienceRestriction></saml:Conditions><saml:AuthnStatement xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion" AuthnInstant="2013-05-23T13:54:34.814Z"><saml:AuthnContext xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion"><saml:AuthnContextClassRef xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion">urn:oasis:names:tc:SAML:2.0:cm:holder-of-key</saml:AuthnContextClassRef></saml:AuthnContext></saml:AuthnStatement></saml:Assertion><wsc:DerivedKeyToken xmlns:wsc="http://docs.oasis-open.org/ws-sx/ws-secureconversation/200512" wsu:Id="DK-3"><wsse:SecurityTokenReference xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd" xmlns:wsse11="http://docs.oasis-open.org/wss/oasis-wss-wssecurity-secext-1.1.xsd" wsse11:TokenType="http://docs.oasis-open.org/wss/oasis-wss-saml-token-profile-1.1#SAMLV2.0"><wsse:KeyIdentifier xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd" ValueType="http://docs.oasis-open.org/wss/oasis-wss-saml-token-profile-1.1#SAMLID">#ID_2107d9c4-cf0f-402d-9287-8c90816a1825</wsse:KeyIdentifier></wsse:SecurityTokenReference><wsc:Offset>0</wsc:Offset><wsc:Length>16</wsc:Length><wsc:Nonce>iFzF77T5AhTqn6UfYvYRvg==</wsc:Nonce></wsc:DerivedKeyToken><ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#" Id="SIG-4"><ds:SignedInfo><ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"><ec:InclusiveNamespaces xmlns:ec="http://www.w3.org/2001/10/xml-exc-c14n#" PrefixList="soap"/></ds:CanonicalizationMethod><ds:SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#hmac-sha1"/><ds:Reference URI="#TS-2"><ds:Transforms><ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"><ec:InclusiveNamespaces xmlns:ec="http://www.w3.org/2001/10/xml-exc-c14n#" PrefixList="wsse soap"/></ds:Transform></ds:Transforms><ds:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/><ds:DigestValue>2NkS3TRf1dFWGKwRr6MxyaZ4u0w=</ds:DigestValue></ds:Reference></ds:SignedInfo><ds:SignatureValue>EWgsNxfXWOe1QKWRor8qwuntGz0=</ds:SignatureValue><ds:KeyInfo Id="KI-9A1F52EBD1712881EB13693172750241"><wsse:SecurityTokenReference wsu:Id="STR-9A1F52EBD1712881EB13693172750262"><wsse:Reference URI="#DK-3"/></wsse:SecurityTokenReference></ds:KeyInfo></ds:Signature></wsse:Security></soap:Header><soap:Body><ns2:SRT_TEST_STATELESS xmlns:ns2="urn:sap-com:document:sap:rfc:functions"><IM_ERROR></IM_ERROR><IM_STRING>pippo</IM_STRING></ns2:SRT_TEST_STATELESS></soap:Body></soap:Envelope>


Here is the keyidentifier contained in the envelope:

<wsse:KeyIdentifier xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd" ValueType="http://docs.oasis-open.org/wss/oasis-wss-saml-token-profile-1.1#SAMLID">#ID_2107d9c4-cf0f-402d-9287-8c90816a1825</wsse:KeyIdentifier>

As you can see the id ID_2107d9c4-cf0f-402d-9287-8c90816a1825 has an # before it.