Revision Summary Date Revision History Revision Class Comments 12/18/2006 0.1 New Version 0.1 release 3/2/2007 1.0 Major Version 1.0 release 4/3/2007 1.1 Minor Version 1.1 release 5/11/2007 1.2 Minor Version 1.2 release 6/1/2007 2.0 Major Updated and revised the technical content. 7/3/2007 2.1 Minor Clarified the meaning of the technical content. 7/20/2007 3.0 Major Rewrite to include dependencies on Netlogon. 8/10/2007 3.0.1 Editorial Changed language and formatting in the technical content. 9/28/2007 3.0.2 Editorial Changed language and formatting in the technical content. 10/23/2007 3.0.3 Editorial Changed language and formatting in the technical content. 11/30/2007 3.1 Minor Replaced reference for SNTP. 1/25/2008 3.2 Minor Clarified the meaning of the technical content. 3/14/2008 4.0 Major Updated and revised the technical content.
5/16/2008 4.0.1 Editorial Changed language and formatting in the technical content. 6/20/2008 4.0.2 Editorial Changed language and formatting in the technical content. 7/25/2008 4.1 Clarified the meaning of the technical content. 8/29/2008 4.1.1 Editorial Changed language and formatting in the technical content. 10/24/2008 4.1.2 Editorial Changed language and formatting in the technical content. 12/5/2008 5.0 Updated and revised the technical content. 1/16/2009 6.0 Major Updated and revised the technical content. 2/27/2009 7.0 Major Updated and revised the technical content. 4/10/2009 8.0 Major Updated and revised the technical content. 5/22/2009 9.0 Major Updated and revised the technical content. 7/2/2009 10.0 Major Updated and revised the technical content. 8/14/2009 10.1 Minor Clarified the meaning of
the technical content. 9/25/2009 10.2 Clarified the meaning of the technical content. 11/6/2009 10.3 Minor Clarified the meaning of the technical content. 12/18/2009 11.0 Major Updated and revised the technical content. 1/29/2010 12.0 Major Updated and revised the technical content. 3/12/2010 12.0.1 Editorial Changed language and formatting in the technical content. 4/23/2010 13.0 Major Updated and revised the technical content. 6/4/2010 14.0 Major Updated and revised the technical content. 7/16/2010 15.0 Major Updated and revised the technical content. 8/27/2010 16.0 Major Updated and revised the technical content. 10/8/2010 17.0 Major Updated and revised the technical content. 11/19/2010 18.0 Updated and revised the technical content. 1/7/2011 19.0 Updated and revised the
technical content. 2/11/2011 20.0 Major Updated and revised the technical content. 3/25/2011 20.0 None No changes to the meaning, language, or formatting of the technical content. 5/6/2011 20.0 None No changes to the meaning, language, or formatting of the technical content. 6/17/2011 20.1 Minor Clarified the meaning of the technical content. 9/23/2011 20.1 None No changes to the meaning, language, or formatting of the technical content. 12/16/2011 21.0 Major Updated and revised the technical content. 3/30/2012 21.0 None No changes to the meaning, language, or formatting of the technical content. 7/12/2012 22.0 Major Updated and revised the technical content. 10/25/2012 23.0 Major Updated and revised the technical content. 1/31/2013 23.0 None No changes to the
meaning, language, or formatting of the technical content. 8/8/2013 24.0 Major Updated and revised the technical content. 11/14/2013 24.0 None No changes to the meaning, language, or formatting of the technical content. 2/13/2014 24.0 None No changes to the meaning, language, or formatting of the technical content. 5/15/2014 24.0 None No changes to the meaning, language, or formatting of the technical content. 6/30/2015 25.0 Major Significantly changed the technical content. 10/16/2015 25.0 None No changes to the meaning, language, or formatting of the technical content. 7/14/2016 26.0 Significantly changed the technical content. 6/1/2017 27.0 Major Significantly changed the technical content.
Client Configuration for Authentication A client might need to be manually configured to participate in the NTP Authentication Extensions detailed in this specification. On a machine that is joined to a domain, the client uses these authentication extensions to synchronize time. Applicability Statement The NTP Authentication Extensions are designed for authenticated time synchronization in domains between clients and . Clients that are joined to a domain use the NTP Authentication Extensions to synchronize time. Versioning and Capability Negotiation The NTP Authentication Extensions incorporate implicit capability negotiation based on the NTP message length, as described in sections , , and . NTP version 3, as specified in , and SNTP version 4, as specified in , apply to this extension. Vendor-Extensible Fields The NTP Authentication Extensions do not define any vendor-extensible fields. They do, however, redefine the Authenticator field of from 96 to 160 bits (per ), as described in section . Standards Assignments The NTP Authentication Extensions do not use any additional standards assignments other than the ones in the base protocols.
0 1 2 3 4 5 6 7 8 9 1 0 1 2 3 4 5 6 7 8 9 2 0 1 2 3 4 5 6 7 8 9 3 0 1 Key Identifier Reserved Flags ClientHashIDHints SignatureHashID Crypto-Checksum (64 bytes) ... ... Key Identifier (4 bytes): A 32-bit, unsigned integer in little-endian byte order (least significant byte first). This field identifies the cryptographic key used to generate the crypto-checksum. Reserved (1 byte): MUST be set to zero and MUST be ignored upon receipt. Flags (1 byte): An 8-bit, unsigned integer in little-endian byte order that contains bit values from the following table. All other values are reserved for future use. Value Meaning USE_OLDKEY_VERSION 0x00000001 The older cryptographic key of the pair of keys associated with the account is used. ClientHashIDHints (1 byte): An 8-bit, unsigned integer in little-endian byte order that contains bit values from the following table. All other values are reserved for future use. Value Meaning NTLM_PWD_HASH 0x00000001 The client supports the mechanism described in section for computing the SignatureHashID (1 byte): An 8-bit, unsigned integer in little-endian byte order containing one of the values from the following table. All other values are reserved for future use. Value Meaning NTLM_PWD_HASH 0x00000001 The Crypto-CheckSum field was computed using the mechanism described in section 3.1.5.5. Crypto-Checksum (64 bytes): A 512-bit crypto-checksum that the encryption procedure computes. Server ExtendedAuthenticator NTP Response The subfields of the ExtendedAuthenticator field of the Server ExtendedAuthenticator NTP Response message include the following. 0 1 2 3 4 5 6 7 8 9 1 0 1 2 3 4 5 6 7 8 9 2 0 1 2 3 4 5 6 7 8 9 3 0 1 Key Identifier
(exactly as it was received from the server's peer) to the client that is identified by the Address field in the entry, as described in [RFC1305] section 3.4.2. If a matching entry is not found in ChainingCache, the response is processed as described in section . Non-Domain Controller Processing of the Authenticated Server NTP Response If the server is not a or an , the server MUST ignore the client request without responding. LocalClockDispersion Processing If the ADM element sys.refid is set to "LOCL", then the server MUST set the Root Dispersion (sys.rootdispersion) ADM element to the value of the LocalClockDispersion element. The sys.refid and sys.rootdispersion ADM elements are defined in section 3.2.1, "Common Variables". Chaining-Cache Cleaning Processing To the chaining cache, each entry in the ChainingCache ADM element is processed using the following logic. If the ArrivalTime of the entry indicates a time that is prior to the current time minus the value of the ChainingEntryTimeout ADM element, the entry MUST be removed from ChainingCache. If the ArrivalTime of the entry indicates a time that is after the current time, the entry MUST be removed from ChainingCache. Timer Events No events are used. Local Events No additional events are used.
A Abstract data model 16 32 10 10 B 8 C 10 50 Client 16 31 32 23 initialization ( 21, 32) 31 24 13 31 24 31 20 10 14 13 31 D Data model - abstract 16 32 32 E 41 14 14 9 F 10 G 6 H Higher-layer triggered events 23 36 I 44 44 8 Initialization client ( 21, 32) 32 34 6 L events 31 40 M Message processing 24 36 Messages 14 13 11 14 13 11 11 N 7 13 13 O Other local events 31 40 P 44 44 10 10 45 Protocol Details 16 R 7 8 7 9