<div class="content" name="SECURITYBINDING" uuid="785c00a1-6637-412e-8167-befb0710022e"><p>The SECURITYBINDING structure describes an <a href="ba4c4d80-ef81-49b4-848f-9714d72b5c01#gt_8a7f6700-8311-45bc-af10-82e10accd331" data-linktype="relative-path">RPC</a> <a href="ba4c4d80-ef81-49b4-848f-9714d72b5c01#gt_05fd3925-0672-4f24-9dd9-2b9d441eb333" data-linktype="relative-path">security provider</a> and a <a href="ba4c4d80-ef81-49b4-848f-9714d72b5c01#gt_547217ca-134f-4b43-b375-f5bca4c16ce4" data-linktype="relative-path">service principal name (SPN)</a>.
A client uses these to communicate with either an <a href="ba4c4d80-ef81-49b4-848f-9714d72b5c01#gt_19f75354-9b0b-47cb-a00b-4ff196883b32" data-linktype="relative-path">object resolver</a> or an <a href="ba4c4d80-ef81-49b4-848f-9714d72b5c01#gt_5b284f60-ee33-4d15-9a7b-0fb82d7c6b68" data-linktype="relative-path">object exporter</a>.</p><table>
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 <tr>
  <td colspan="16">wAuthnSvc</td>
  <td colspan="16">Reserved (optional)</td>
 </tr>
 <tr>
  <td colspan="32">aPrincName (variable)</td>
 </tr>
 <tr>
  <td colspan="32">...</td>
 </tr>
</tbody></table><p><b>wAuthnSvc (2 bytes): </b> An RPC security provider
constant, as specified in <a href="../ms-rpce/290c38b1-92fe-4229-91e6-4fc376610c15" data-linktype="relative-path">[MS-RPCE]</a>
section <a href="../ms-rpce/d4097450-c62f-484b-872f-ddf59a7a0d36" data-linktype="relative-path">2.2.1.1.7</a>.
This field MUST NOT contain the value RPC_C_AUTHN_DEFAULT. Additionally, if
this field is RPC_C_AUTHN_NONE, the <b>Reserved</b> and <b>aPrincName</b>
fields MUST NOT be present, and this indicates that the client MUST NOT use any
security on the ORPC invocations (see section <a href="a32b1703-e8dc-4940-9624-825ccc7db328" data-linktype="relative-path">3.2.4.2</a>). If this field is
not RPC_C_AUTHN_NONE, the <b>Reserved</b> and <b>aPrincName</b> fields MUST be
present.</p><p><b>Reserved (2 bytes): </b>If present, MUST be set to
0xffff when sent and MUST be ignored on receipt. </p><p><b>aPrincName (variable): </b>An optional
null-terminated Unicode string that, if present, MUST contain an SPN. An empty
null-terminated Unicode string in this field indicates that no SPN is
specified, and the client MUST NOT use an SPN for the ORPC invocations (see
section 3.2.4.2).</p></div>