[MS-RDPELE]:
Remote Desktop Protocol: Licensing Extension
Intellectual Property Rights Notice for Open Specifications Documentation
Technical Documentation. Microsoft publishes Open Specifications documentation for protocols, file formats, languages, standards as well as overviews of the interaction among each of these technologies.
Copyrights. This documentation is covered by Microsoft copyrights. Regardless of any other terms that are contained in the terms of use for the Microsoft website that hosts this documentation, you may make copies of it in order to develop implementations of the technologies described in the Open Specifications and may distribute portions of it in your implementations using these technologies or your documentation as necessary to properly document the implementation. You may also distribute in your implementation, with or without modification, any schema, IDL's, or code samples that are included in the documentation. This permission also applies to any documents that are referenced in the Open Specifications.
No Trade Secrets. Microsoft does not claim any trade secret rights in this documentation.
Patents. Microsoft has patents that may cover your implementations of the technologies described in the Open Specifications. Neither this notice nor Microsoft's delivery of the documentation grants any licenses under those or any other Microsoft patents. However, a given Open Specification may be covered by Microsoft Open Specification Promise or the Community Promise. If you would prefer a written license, or if the technologies described in the Open Specifications are not covered by the Open Specifications Promise or Community Promise, as applicable, patent licenses are available by contacting .
Trademarks. The names of companies and products contained in this documentation may be covered by trademarks or similar intellectual property rights. This notice does not grant any licenses under those rights. For a list of Microsoft trademarks, visit
Fictitious Names. The example companies, organizations, products, domain names, e-mail addresses, logos, people, places, and events depicted in this documentation are fictitious. No association with any real company, organization, product, domain name, email address, logo, person, place, or event is intended or should be inferred.
Reservation of Rights. All other rights are reserved, and this notice does not grant any rights other than specifically described above, whether by implication, estoppel, or otherwise.
Tools. The Open Specifications do not require the use of Microsoft programming tools or programming environments in order for you to develop an implementation. If you have access to Microsoft programming tools and environments you are free to take advantage of them. Certain Open Specifications are intended for use in conjunction with publicly available standard specifications and network programming art, and assumes that the reader either is familiar with the aforementioned material or has immediate access to it.
Revision Summary
Date / Revision History / Revision Class / Comments7/20/2007 / 0.1 / Major / MCPP Milestone 5 Initial Availability
9/28/2007 / 0.2 / Minor / Clarified the meaning of the technical content.
10/23/2007 / 0.3 / Minor / Clarified the meaning of the technical content.
11/30/2007 / 0.4 / Minor / Clarified the meaning of the technical content.
1/25/2008 / 0.4.1 / Editorial / Changed language and formatting in the technical content.
3/14/2008 / 0.5 / Minor / Clarified the meaning of the technical content.
5/16/2008 / 0.5.1 / Editorial / Changed language and formatting in the technical content.
6/20/2008 / 1.0 / Major / Updated and revised the technical content.
7/25/2008 / 2.0 / Major / Updated and revised the technical content.
8/29/2008 / 2.1 / Minor / Clarified the meaning of the technical content.
10/24/2008 / 2.2 / Minor / Clarified the meaning of the technical content.
12/5/2008 / 3.0 / Major / Updated and revised the technical content.
1/16/2009 / 3.0.1 / Editorial / Changed language and formatting in the technical content.
2/27/2009 / 4.0 / Major / Updated and revised the technical content.
4/10/2009 / 4.1 / Minor / Clarified the meaning of the technical content.
5/22/2009 / 4.1.1 / Editorial / Changed language and formatting in the technical content.
7/2/2009 / 4.1.2 / Editorial / Changed language and formatting in the technical content.
8/14/2009 / 4.2 / Minor / Clarified the meaning of the technical content.
9/25/2009 / 4.3 / Minor / Clarified the meaning of the technical content.
11/6/2009 / 4.3.1 / Editorial / Changed language and formatting in the technical content.
12/18/2009 / 5.0 / Major / Updated and revised the technical content.
1/29/2010 / 5.1 / Minor / Clarified the meaning of the technical content.
3/12/2010 / 6.0 / Major / Updated and revised the technical content.
4/23/2010 / 7.0 / Major / Updated and revised the technical content.
6/4/2010 / 8.0 / Major / Updated and revised the technical content.
7/16/2010 / 8.1 / Minor / Clarified the meaning of the technical content.
8/27/2010 / 9.0 / Major / Updated and revised the technical content.
10/8/2010 / 10.0 / Major / Updated and revised the technical content.
11/19/2010 / 10.0 / None / No changes to the meaning, language, or formatting of the technical content.
1/7/2011 / 10.0 / None / No changes to the meaning, language, or formatting of the technical content.
2/11/2011 / 10.0 / None / No changes to the meaning, language, or formatting of the technical content.
3/25/2011 / 10.0 / None / No changes to the meaning, language, or formatting of the technical content.
5/6/2011 / 10.0 / None / No changes to the meaning, language, or formatting of the technical content.
6/17/2011 / 10.1 / Minor / Clarified the meaning of the technical content.
9/23/2011 / 10.1 / None / No changes to the meaning, language, or formatting of the technical content.
12/16/2011 / 11.0 / Major / Updated and revised the technical content.
3/30/2012 / 11.0 / None / No changes to the meaning, language, or formatting of the technical content.
7/12/2012 / 11.1 / Minor / Clarified the meaning of the technical content.
10/25/2012 / 11.2 / Minor / Clarified the meaning of the technical content.
1/31/2013 / 11.2 / None / No changes to the meaning, language, or formatting of the technical content.
8/8/2013 / 11.2 / None / No changes to the meaning, language, or formatting of the technical content.
11/14/2013 / 11.2 / None / No changes to the meaning, language, or formatting of the technical content.
2/13/2014 / 11.2 / None / No changes to the meaning, language, or formatting of the technical content.
5/15/2014 / 11.2 / None / No changes to the meaning, language, or formatting of the technical content.
6/30/2015 / 12.0 / Major / Significantly changed the technical content.
10/16/2015 / 12.0 / No Change / No changes to the meaning, language, or formatting of the technical content.
Table of Contents
1Introduction
1.1Glossary
1.2References
1.2.1Normative References
1.2.2Informative References
1.3Overview
1.3.1Licensing Architecture
1.3.2X.509 Certificate Chains
1.3.3Licensing PDU Flows
1.3.3.1New License Flow
1.3.3.2Upgrade License Flow
1.4Relationship to Other Protocols
1.5Prerequisites/Preconditions
1.6Applicability Statement
1.7Versioning and Capability Negotiation
1.8Vendor-Extensible Fields
1.9Standards Assignments
2Messages
2.1Transport
2.2Message Syntax
2.2.1Common Data Structures
2.2.1.1Security Headers
2.2.1.1.1Basic (TS_SECURITY_HEADER)
2.2.1.1.2Non-FIPS (TS_SECURITY_HEADER1)
2.2.1.1.3FIPS (TS_SECURITY_HEADER2)
2.2.1.2Licensing Preamble (LICENSE_PREAMBLE)
2.2.1.3Licensing Binary BLOB (LICENSE_BINARY_BLOB)
2.2.1.4Server Certificate (SERVER_CERTIFICATE)
2.2.1.4.1Server Proprietary Certificate (PROPRIETARYSERVERCERTIFICATE)
2.2.1.4.2X.509 Certificate Chain (X509 _CERTIFICATE_CHAIN)
2.2.1.4.2.1CertBlob (CERT_BLOB)
2.2.1.4.3Proprietary Certificate (PROPRIETARYSERVERCERTIFICATE)
2.2.2Licensing PDU (TS_LICENSING_PDU)
2.2.2.1Server License Request (SERVER_LICENSE_REQUEST)
2.2.2.1.1Product Information (PRODUCT_INFO)
2.2.2.1.2Scope List (SCOPE_LIST)
2.2.2.1.2.1Scope (SCOPE)
2.2.2.2Client New License Request (CLIENT_NEW_LICENSE_REQUEST)
2.2.2.3Client License Information (CLIENT_LICENSE_INFO)
2.2.2.3.1Client Hardware Identification (CLIENT_HARDWARE_ID)
2.2.2.4Server Platform Challenge (SERVER_PLATFORM_CHALLENGE)
2.2.2.5Client Platform Challenge Response (CLIENT_PLATFORM_CHALLENGE_RESPONSE)
2.2.2.5.1Platform Challenge Response Data (PLATFORM_CHALLENGE_RESPONSE_DATA)
2.2.2.6Server Upgrade License (SERVER_UPGRADE_LICENSE)
2.2.2.6.1New License Information (NEW_LICENSE_INFO)
2.2.2.7Server New License (SERVER_NEW_LICENSE)
2.2.2.7.1License Error Message (LICENSE_ERROR_MESSAGE)
3Protocol Details
3.1Common Details
3.1.1Abstract Data Model
3.1.2Timers
3.1.3Initialization
3.1.4Higher-Layer Triggered Events
3.1.5Message Processing Events and Sequencing Rules
3.1.5.1Message Integrity Checking
3.1.5.2Sending License Error Messages
3.1.5.3Processing License Error Messages
3.1.5.3.1Client State Transition
3.1.5.3.2Server State Transition
3.1.6Timer Events
3.1.7Other Local Events
3.2Server Details
3.2.1Abstract Data Model
3.2.1.1Server Random
3.2.1.2Product Information
3.2.1.3Server Certificate
3.2.1.4Key Exchange List
3.2.1.5Scope List
3.2.1.6Platform Challenge
3.2.1.7License
3.2.1.8ClientUserName
3.2.1.9ClientMachineName
3.2.1.10Encryption Keys
3.2.1.11Server Licensing States
3.2.2Timers
3.2.3Initialization
3.2.4Higher-Layer Triggered Events
3.2.5Message Processing Events and Sequencing Rules
3.2.5.1Sending Server License Request PDUs
3.2.5.2Processing Client New License Requests
3.2.5.3Processing Client License Information
3.2.5.4Sending Server Platform Challenges
3.2.5.5Processing Client Platform Challenge Responses
3.2.5.6Sending Server Upgrade Licenses
3.2.5.7Sending Server New Licenses
3.2.5.8Handling Out-of-Sequence or Unrecognized Messages
3.2.5.9Handling Invalid MACs
3.2.6Timer Events
3.2.7Other Local Events
3.3Client Details
3.3.1Abstract Data Model
3.3.1.1Platform ID
3.3.1.2Client Random
3.3.1.3Preferred Key Exchange Algorithm ID
3.3.1.4Client User Name
3.3.1.5Client Machine Name
3.3.1.6Encrypted Premaster Secret
3.3.1.7License
3.3.1.8License Store
3.3.1.9Client Hardware Identification
3.3.1.10Encryption Keys
3.3.1.11Client Licensing States
3.3.2Timers
3.3.2.1Client Packet Wait Timer
3.3.3Initialization
3.3.4Higher-Layer Triggered Events
3.3.5Message Processing Events and Sequencing Rules
3.3.5.1Processing Server License Requests
3.3.5.2Sending Client New License Requests
3.3.5.3Sending Client License Information
3.3.5.4Processing Server Platform Challenges
3.3.5.5Sending Client Platform Challenge Responses
3.3.5.6Processing Server Upgrade Licenses
3.3.5.7Processing Server New Licenses
3.3.5.8Handling Out-of-Sequence or Unrecognized Messages
3.3.5.9Handling Invalid MACs
3.3.6Timer Events
3.3.7Other Local Events
4Protocol Examples
4.1SERVER LICENSE REQUEST
4.2CLIENT NEW LICENSE REQUEST
4.3CLIENT LICENSE INFO
4.4SERVER PLATFORM CHALLENGE
4.5CLIENT PLATFORM CHALLENGE RESPONSE
4.6SERVER NEW LICENSE
4.7SERVER UPGRADE LICENSE
5Security
5.1Security Considerations for Implementers
5.1.1X.509 Certificate
5.1.2Client and Server Random Values and Premaster Secrets
5.1.2.1Encrypting the Premaster Secret
5.1.2.2Decrypting the Premaster Secret
5.1.3Generating the Licensing Encryption and MAC Salt Keys
5.1.4Encrypting Licensing Session Data
5.1.5Decrypting Licensing Session Data
5.1.6MAC Generation
5.2Index of Security Parameters
6Appendix A: Product Behavior
7Change Tracking
8Index
1Introduction
The Remote Desktop Protocol: Licensing Extension expands on the licensing protocol sequence specified in [MS-RDPBCGR].
Sections 1.8, 2, and 3 of this specification are normative and can contain the terms MAY, SHOULD, MUST, MUST NOT, and SHOULD NOT as defined in [RFC2119]. Sections 1.5 and 1.9 are also normative but do not contain those terms. All other sections and examples in this specification are informative.
1.1Glossary
The following terms are specific to this document:
Active Directory: A general-purpose network directory service. Active Directory also refers to the Windows implementation of a directory service. Active Directory stores information about a variety of objects in the network. Importantly, user accounts, computer accounts, groups, and all related credential information used by the Windows implementation of Kerberos are stored in Active Directory. Active Directory is either deployed as Active Directory Domain Services (AD DS) or Active Directory Lightweight Directory Services (AD LDS). [MS-ADTS] describes both forms. For more information, see [MS-AUTHSOD] section 1.1.1.5.2, Lightweight Directory Access Protocol (LDAP) versions 2 and 3, Kerberos, and DNS.
American National Standards Institute (ANSI) character set: A character set (1) defined by a code page approved by the American National Standards Institute (ANSI). The term "ANSI" as used to signify Windows code pages is a historical reference and a misnomer that persists in the Windows community. The source of this misnomer stems from the fact that the Windows code page 1252 was originally based on an ANSI draft, which became International Organization for Standardization (ISO) Standard 8859-1 [ISO/IEC-8859-1]. In Windows, the ANSI character set can be any of the following code pages: 1252, 1250, 1251, 1253, 1254, 1255, 1256, 1257, 1258, 874, 932, 936, 949, or 950. For example, "ANSI application" is usually a reference to a non-Unicode or code-page-based application. Therefore, "ANSI character set" is often misused to refer to one of the character sets defined by a Windows code page that can be used as an active system code page; for example, character sets defined by code page 1252 or character sets defined by code page 950. Windows is now based on Unicode, so the use of ANSI character sets is strongly discouraged unless they are used to interoperate with legacy applications or legacy data.
clearing house: A Microsoft central authority for activating a license server and registering client access licenses (CALs).
client: A computer on which the remote procedure call (RPC) client is executing.
client access license (CAL): A license required by a client user or device for accessing a terminal server configured in Application Server mode.
client license: See client access license (CAL).
grace period: The duration of time during which a terminal server allows clients to connect without requiring a CAL. The grace period ends either when the duration is complete or when the terminal server receives the first permanent license from the license server.
license encryption key: A shared symmetric key generated by both the server and client that is used to encrypt licensing message data.
license server: A server that issues CALs.
license server certificate: An X.509 certificate used for signing CALs.
license store: A client-side database that stores CALs issued by a terminal server.
MD5 digest: A 128-bit message hash value generated as output by the MD5 Message-Digest algorithm. See [RFC1321].
Message Authentication Code (MAC): A message authenticator computed through the use of a symmetric key. A MAC algorithm accepts a secret key and a data buffer, and outputs a MAC. The data and MAC can then be sent to another party, which can verify the integrity and authenticity of the data by using the same secret key and the same MAC algorithm.
object identifier (OID): In the context of a directory service, a number identifying an object class or attribute (2). Object identifiers are issued by the ITU and form a hierarchy. An OID is represented as a dotted decimal string (for example, "1.2.3.4"). For more information on OIDs, see [X660] and [RFC3280] Appendix A. OIDs are used to uniquely identify certificate templates available to the certification authority (CA). Within a certificate (1), OIDs are used to identify standard extensions, as described in [RFC3280] section 4.2.1.x, as well as non-standard extensions.
permanent license: A CAL issued to authenticated clients.
personal terminal server: In general context, refers to a client SKU target machine that hosts remote desktop sessions. From a terminal service licensing perspective, the behavior of a personal terminal server is similar to that of a terminal server in remote administration mode. Thus any behavioral reference to a personal terminal server in this document essentially implies that the particular behavior is valid for a terminal server in remote administration mode as well. The term personal terminal server is therefore used to encompass all connections where either the end point is a client SKU operating system or is a terminal server running in remote administration mode.
premaster secret: A 48-byte random number used in license encryption key generation.
RC4: A variable key-length symmetric encryption algorithm. For more information, see [SCHNEIER] section 17.1.
remote administration mode: A terminal server may function in remote administration mode if either the terminal services role is not installed on the machine or the client used to invoke the session has enabled the /admin switch. The administrator can log in to the terminal server (with Windows Server 2003 operating system with Service Pack 2 (SP2), Windows Server 2008 operating system, Windows Server 2008 R2 operating system, Windows Server 2012 operating system, or Windows Server 2012 R2 operating system) in the remote administration mode by using the following command from any Remote Desktop client (with Terminal Services Client version 6.0 or 6.1). “mstsc /admin <remote machine name>”
Remote Desktop client: A device that connects to a terminal server and renders the user interface through which a user interacts with a remote session.
Remote Desktop Protocol (RDP): A multi-channel protocol that allows a user to connect to a computer running Microsoft Terminal Services (TS). RDP enables the exchange of client and server settings and also enables negotiation of common settings to use for the duration of the connection, so that input, graphics, and other data can be exchanged and processed between client and server.
server: A computer on which the remote procedure call (RPC) server is executing.
session encryption key: A shared key used for confidential exchange of data between the client and the server.
SHA-1 hash: A hashing algorithm as specified in [FIPS180-2] that was developed by the National Institute of Standards and Technology (NIST) and the National Security Agency (NSA).
temporary license: A type of CAL issued by a terminal server to a client in situations in which a permanent license is not available.
terminal server: The server to which a client initiates a remote desktop connection. The server hosts Remote Desktop sessions and enables interaction with each of these sessions on a connected client device.
terminal server certificate: A certificate that should be used to authenticate a terminal server.
Unicode string: A Unicode 8-bit string is an ordered sequence of 8-bit units, a Unicode 16-bit string is an ordered sequence of 16-bit code units, and a Unicode 32-bit string is an ordered sequence of 32-bit code units. In some cases, it may be acceptable not to terminate with a terminating null character. Unless otherwise specified, all Unicode strings follow the UTF-16LE encoding scheme with no Byte Order Mark (BOM).
MAY, SHOULD, MUST, SHOULD NOT, MUST NOT: These terms (in all caps) are used as defined in [RFC2119]. All statements of optional behavior use either MAY, SHOULD, or SHOULD NOT.
1.2References
Links to a document in the Microsoft Open Specifications library point to the correct section in the most recently published version of the referenced document. However, because individual documents in the library are not updated at the same time, the section numbers in the documents may not match. You can confirm the correct section numbering by checking the Errata.
1.2.1Normative References
We conduct frequent surveys of the normative references to assure their continued availability. If you have any issue with finding a normative reference, please contact . We will assist you in finding the relevant information.
[ISO/IEC-8859-1] International Organization for Standardization, "Information Technology -- 8-Bit Single-Byte Coded Graphic Character Sets -- Part 1: Latin Alphabet No. 1", ISO/IEC 8859-1, 1998,
Note There is a charge to download the specification.
[MS-RDPBCGR] Microsoft Corporation, "Remote Desktop Protocol: Basic Connectivity and Graphics Remoting".
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997,
[RFC3280] Housley, R., Polk, W., Ford, W., and Solo, D., "Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile", RFC 3280, April 2002,
[T123] ITU-T, "Network-Specific Data Protocol Stacks for Multimedia Conferencing", Recommendation T.123, May 1999,
Note There is a charge to download the specification.
[T125] ITU-T, "Multipoint Communication Service Protocol Specification", Recommendation T.125, February 1998,
Note There is a charge to download the specification.
[X224] ITU-T, "Information technology - Open Systems Interconnection - Protocol for Providing the Connection-Mode Transport Service", Recommendation X.224, November 1995,
Note There is a charge to download the specification.
1.2.2Informative References
[MS-EERR] Microsoft Corporation, "ExtendedError Remote Data Structure".
[MSDN-CAI] Microsoft Corporation, "CRYPT_ALGORITHM_IDENTIFIER structure",
[MSDN-OSVER] Microsoft Corporation, "Operating System Version",
[MSDN-RC4] Microsoft Corporation, "MSDN Security Glossary",
1.3Overview
The Remote Desktop Protocol: Licensing Extension is designed to allow authorized remote desktop clients or users to connect to a terminal server (A reference to terminal server in this document generally implies a terminal server in app-server mode). It involves communication between a Remote Desktop client, a terminal server, and a license server. The terminal server can be configured to function in per-device or per-user license mode. Client access licenses (CALs) are installed on a license server, so that when a terminal server requests a license on a client's behalf, the license server issues a license out of its available pool of licenses.