Abstract:
A method of licensing software to a particular instance of a virtual machine that is being run as part of an Active Directory domain. Since a virtual machine is a simulation of a physical machine, i.e. a computer, it can easily be cloned to produce an exact duplicate. This poses a problem when it is desired to license an instance of software for use only on a particular virtual machine. The technology disclosed allows for software to be licensed for execution only on a particular instance of a virtual machine that is being run as part of an Active Directory domain.

Description:
BACKGROUND 
       [0001]    The technology disclosed relates to licensing software executing on virtual machines. Since a virtual machine is a simulation of a physical machine, i.e. a computer, it can easily be cloned to produce an exact duplicate. This poses a problem when it is desired to license an instance of software for use only on a particular virtual machine. 
         [0002]    Historically one of the primary software licensing methods has been to license software, such as an instance of a software application, such that it is only permitted to execute on a particular physical computer or “node” in a computer network. Another name for a node is a “machine.” In this sense the software license “locks” the software to the particular physical computer and hence the term “node-locked” license. 
         [0003]    This type of license makes use of unique characteristics of a node, such as the physical computing hardware, to identify a node, and lock the desired software license to it. This is typically done by executing licensing software on the node being licensed that retrieves a unique identifying characteristic of the machine such as the MAC address of a network card or the serial number of the main hard drive and sending this information to a remote license server which grants a license, in the form of license data, to the node. The licensing software then stores the license data in a location accessible to the node, such as a local disk drive or a network drive. The licensing software may or may not be part of the software being licensed. If it is not part of the software being licensed it is typically a software module that is called by the software being licensed. 
         [0004]    Upon execution, the software being licensed then invokes the licensing software which obtains the unique identifying characteristic of the node and compares it to unique identifying characteristic in the stored license data. If they match, the software being licensed continues execution normally. Otherwise it terminates execution and usually notifies the user that the license was not valid. 
         [0005]    However, the absence of a unique physical characteristic for a virtual machine renders the above methods unusable for licensing software operating on a virtual machine, since a virtual machine, even though it may be a complete simulation of a physical machine (computer), may easily be cloned to produce an exact copy with exactly the same characteristics as the original from which it was cloned. 
         [0006]    Thus, with the large number of virtual machines now in use, it is therefore desirable to devise a method that would provide a unique identifier for a virtual machine such as a digitally readable identification code that can be used for licensing purposes. 
       SUMMARY 
       [0007]    The technology disclosed provides a method of licensing software to a particular instance of a Microsoft Windows® operating system executing on a virtual machine, abbreviated VM, which belongs to a Microsoft Windows® Active Directory domain. There is a distinction here to be made between a VM and an operating system, abbreviated OS, running on the VM. Since a virtual machine is a simulation of a physical machine, i.e. a computer, it can easily be cloned to produce an exact duplicate. Furthermore, multiple operating systems can be run on both a physical machine and a VM simultaneously. This poses a problem when it is desired to license an instance of software for use only with a particular instance of an OS running on a VM. The technology disclosed provides a solution is intended to be used with installations of Microsoft Windows® OSs and applies to Active Directory domains implemented using Microsoft products as well as those implemented to conform to Microsoft&#39;s design. 
         [0008]    In brief, Microsoft Windows® provides Active Directory domain services which are run on Windows servers, and as additional machines running Microsoft Windows® OS, virtual or physical, join a domain, each is assigned a unique machine ID by Active Directory Domain Services. The machine ID is also known as a Relative ID in a Windows® SID, where the SID is a Security Identifier. Even if an exact copy of a VM on the domain is made by a process commonly called “cloning,” when that cloned VM runs Microsoft Windows® OS and joins the domain it is immediately assigned its own unique machine ID different from all other machine IDs on the domain. 
         [0009]    The technology disclosed makes use of the fact that within an enterprise running Active Directory Domain Services, there may be multiple domains, each one having a unique domain ID. Thus, within a collection of domains running under Active Directory domain services the combination of the machine ID and its domain ID may be used to uniquely identify a particular machine. 
         [0010]    The technology disclosed combines a machine ID and its domain ID and transforms it into a unique identifier using a hash function. This unique identifier corresponds directly to the machine ID and the domain ID, and thus it may be used to overcome the limitations of node-locked licensing previously posed by virtual machines. This identifier uniquely identifies a particular instance of Windows® OS. Consequently, this identifier may be used to license software running on a Microsoft Windows® OS running in a VM on an Active Directory in the same way as a unique identifier derived from unique characteristics of a physical machine. 
         [0011]    The unique identifier itself is a hash. A hash, usually performed by a hash function, is the result of performing a transformation that maps a data set of variable or fixed length to a smaller data set of fixed length. Some common hash lengths used for cryptographic purposes are 128 and 256 bits. The most important property of a hash function is collision resistance, i.e., the probability is very low that any two different inputs will produce an identical output value. There are a wide variety of hash implementations which will be apparent to those of ordinary skill in the art. 
         [0012]    Other aspects and advantages of the technology disclosed can be seen on review of the drawings, the detailed description and the claims, which follow. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a block diagram of the environment in which the technology disclosed may be used. 
           [0014]      FIG. 2  is a flowchart of the licensing process from the perspective of the software under license. 
           [0015]      FIG. 3  is a flowchart of the licensing process from the perspective of the license grant application. 
           [0016]      FIG. 4  is a flowchart of license verification process from the perspective of the software under license. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    A detailed description of implementations of the technology disclosed is provided with reference to the  FIGS. 1-3 . 
         [0018]      FIG. 1  is a block diagram of the environment in which the technology disclosed may be used. The main components include installations of Microsoft Windows® OSs running on virtual machines (VMs) which belong to a domain managed by Microsoft Windows® Active Directory services (“Active Directory Services” or “Active Directory”) and a license grant application accessible by the software under license. Five VMs are shown, numbered  101 - 105 , with VM 3   103  being the one that will be used in the example describing  FIG. 1 . There are three basic parts to the license process: 
         [0019]    1. The machine ID and domain ID are assigned by Active Directory. 
         [0020]    2. The software under license obtains a license 
         [0021]    3. The software under license verifies the license 
         [0022]    The first part of the process occurs automatically when a machine ID and a domain ID are assigned by Active Directory when an installation of Microsoft Windows® OS is first run on a VM, such as VM 3  in this example, and joins an Active Directory domain. 
         [0023]    This is indicated in  FIG. 1  by the dotted arrow running from the server  150  to the domain ID and machine ID  110  within VM 3   103 . The combination of the domain ID and the machine ID uniquely identify an instance of Microsoft Windows® OS running on a VM that belongs to a domain being managed by Active Directory services. 
         [0024]    The second part of the process starts by obtaining a unique identifier based on the machine ID and the domain ID. This is accomplished when the software under license generates a hash using a combination of the machine ID and the domain ID as input. The resulting hash is used as a unique identifier which corresponds to the machine ID and its domain ID. This identifier is then incorporated into a license request  120  and sent to the license grant application  160 , which incorporates it into license data, digitally signs the license data and sends it back to the software under license. In some implementations this may be in the form of a license certificate. In others it may be in the form of a license grant response. Both approaches work since they both include the unique identifier used to verify a license. The digitally signed license data  130  is then stored in a location accessible to the software under license. The process of digitally signing data is performed using a digital signature algorithm such as DSA which is a United States Federal Government standard originally proposed by the National Institute of Standards and Technology. Another government standard is the Elliptic Curve Digital Signature Algorithm, or ECDSA. In addition there are other digital signature algorithms such as those based on an RSA public-private key exchange with accompanying encryption. 
         [0025]    The third part of the license process is verification of the license. When the software under license is executed, it retrieves the license data  130  from the location in which it was previously stored, verifies the digital signature and obtains the original unique identifier. This is compared to a new unique identifier obtained by feeding the current machine ID and domain ID into the same hash function as used previously. If the exact same machine ID and domain ID as before are used, then the results of the hash function will be exactly as before and the newly generated unique identifier will match the original one that was digitally signed and stored with the license data, thus successfully verifying the license. 
         [0026]    If the verification is successful, the software under license continues execution. Otherwise it terminates, usually with a message that notifies the user that the verification failed. 
         [0027]      FIG. 2  is a flowchart of the licensing process from the perspective of the software under license. The explanation is similar to that of  FIG. 1 . It begins with step  200  when the software under license obtains the machine ID and the domain ID, combines them and generates a unique identifier using a hash function. 
         [0028]    In Step  210  the unique identifier is incorporated into a license request and sent to a license grant application. 
         [0029]    In step  220  the software under license receives digitally signed license data back from the license grant application. The digitally signed license data includes the unique identifier. The license data may be in the form of a license grant response or a license certificate. There are several alternatives that will be known to those of ordinary skill in the art. 
         [0030]    In Step  230  the license data is stored in a location accessible to the software under license. 
         [0031]      FIG. 3  is a flowchart of the licensing process from the perspective of the license grant application. The explanation is similar to that of  FIG. 1 . It begins with step  300  when the license grant application receives a license request which includes a unique identifier. 
         [0032]    In step  310  the license grant application now generates license data incorporating the unique identifier. 
         [0033]    In step  320  the license grant application digitally signs the license data. In step  330  the license grant application incorporates the digitally signed license data into a license grant response and sends it back to the requestor. 
         [0034]      FIG. 4  is a flowchart of the license verification process from the perspective of the software under license. The explanation is similar to that of  FIG. 1 . It begins with step  400  and in step  410  the software under license obtains the current machine ID and the current domain ID, combines them and generates a current unique identifier using a hash function. 
         [0035]    In step  420  the software under license retrieves the license data  FIG. 1   130  from the location in which it was previously stored in step  FIG. 2   230 , verifies the digital signature and obtains the original unique identifier. This is compared to the current unique identifier obtained above in step  410 . If they match in step  440 , then verification is successful and the software executes normally as in step  450 . If they do not match then the license, based on the license data retrieved above in step  420 , is not valid and in this and most alternate implementations the software under license terminates as in step  460 . 
       Particular Implementations 
       [0036]    The technology disclosed may be practiced as a method or system adapted to practice the method. The process of digitally signing data is performed using a digital signature algorithm such as DSA which is a United States Federal Government standard originally proposed by the National Institute of Standards and Technology. Another government standard is the Elliptic Curve Digital Signature Algorithm, or ECDSA. In addition there are other digital signature algorithms such as those based on an RSA public-private key exchange with accompanying encryption. 
         [0037]    In one implementation, a method is described for managing a software license for software under license running on a Microsoft Windows® OS running on virtual machines (VMs) which belong to a domain managed by Microsoft Windows® Active Directory services. Active Directory is a Microsoft Windows® directory service for Windows domain networks. A domain controller, such as Microsoft&#39;s Active Directory domain services, manages the machines on a domain. A machine ID and a domain ID are assigned by Active Directory when an installation of Microsoft Windows® OS is first run on a VM and joins an Active Directory domain. The combination of the domain ID and the machine ID uniquely identify an instance of Microsoft Windows® OS running on a VM that belongs to a domain being managed by Active Directory services. A unique identifier can be generated using the domain ID and machine ID, and this identifier can be used to license software running on the OS installation. This unique identifier may be incorporated into license data, which may be in the form of a license certificate, that binds the software under license to a particular instance of Microsoft Windows® OS running on virtual machines (VMs) which belong to a domain managed by Microsoft Windows® Active Directory services. 
         [0038]    This method and other implementations the technology disclosed each optionally include one or more the following features. 
         [0039]    The software under license can generate a hash using a combination of the machine ID and the domain ID as input. The resulting hash is used as a unique identifier which corresponds to the machine ID and its domain ID. This identifier is then incorporated into a license request and sent to license grant application, which incorporates it into license data, digitally signs the license data and sends it back to the software under license. The digitally signed license data is then stored in a location accessible to the software under license. 
         [0040]    A unique ID can, alternatively, be constructed by using the machine ID and the domain ID directly as the unique identifier instead of a hash. 
         [0041]    Other implementations may include a non-transitory computer readable storage media storing instructions executable on a processor to perform a method is described above. Yet another implementation may include a system with memory and one or more processors operable to execute instructions, stored in memory, perform the method as described above. This is true of each of the following implementations and will, for the sake of brevity, not be repeated. 
         [0042]    In another implementation, when the software under license is executed, it retrieves the license data from the location in which it was previously stored, verifies the digital signature and obtains the registered unique identifier. This is compared to a current unique identifier obtained by feeding the current machine ID and domain ID into the same hash function as used previously. If the exact same machine ID and domain ID as before are used, then the results of the hash function will be exactly as before and the newly generated unique identifier will match the original one that was digitally signed and stored with the license data, thus successfully verifying the license. If the verification is successful, the software under license continues execution. Otherwise it terminates, usually with a message that notifies the user that the verification failed. 
         [0043]    This implementation can be combined with any of the registration features described above. 
         [0044]    In another implementation, either of the two previous methods could be used with a central license server in place of the license grant application. The license server could Ernie store all the license data in a database and verify incoming license requests against the license data stored in the database. 
         [0045]    In another implementation the software under license executing on an instance of a Microsoft Windows® operating system executing on a VM belonging to an Active Directory domain verifies that it is licensed to run on a particular instance of Microsoft Windows® operating system executing on a VM belonging to an Active Directory domain by comparing a current unique value to a digitally signed registered unique value stored in a location accessible to the software under license, such as a local disk drive or a network drive. 
         [0046]    To register, the software first obtains the values of the machine ID and the domain ID corresponding to the particular instance of Microsoft Windows® operating system executing on a VM belonging to an Active Directory domain. The unique value may be a combination of the machine ID and the domain ID or it may be a value derived the machine ID and the domain ID, such as the result of performing a hash on a combination of the machine ID and the domain ID. In either case, a unique value corresponding to the current machine ID and the current domain ID is obtained and sent to a license grant application digitally signs it and sends it back as license data which may be in the form of a license grant response or license certificate. When the software under license receives the digitally signed license data, it stores it in a location accessible to the software under license, such as a local disk drive or a network drive. This completes the registration process. 
         [0047]    To perform the license verification, the software under license first obtains the current values of the machine ID and the domain ID corresponding to the particular instance of Microsoft Windows® operating system executing on a VM belonging to an Active Directory domain. As noted above, the unique value may be a combination of the machine ID and the domain ID or it may be a value derived the machine ID and the domain ID, such as the result of performing a hash on a combination of the machine ID and the domain ID. In either case, a current unique value corresponding to the current machine ID and the current domain ID is obtained. The emphasis here is on the current values of the machine ID and domain ID as opposed to the values used at a prior time for registration, since the goal is to ensure that they have not changed in the interim and that they match, the process being described below. 
         [0048]    The software now retrieves the digitally signed registered unique value, which may be stored on non-transitory computer readable storage media accessible to the software and verifies the digital signature using any one of several methods, including the digital signature algorithms mentioned elsewhere in this document. 
         [0049]    The final step in the process is to compare the registered unique value to the current unique value, both having been generated in the same manner. In particular, if the same hash function is used to generate both the current and registered unique values, then the result will be exactly equal if they are both generated using the same input values. Alternatively, the combination of a machine ID and domain ID can be used in which case the registered combination of the machine ID and domain ID should match the current combination of the machine ID and domain ID. As explained elsewhere, this latter method is not as efficient or as secure as using a hash. 
         [0050]    Once the current and registered values of the unique ID have been verified to match, the verification process is complete and the software under license may continue execution. If they do not match, then an appropriate message may be sent to the user and the software under license may not continue execution. 
         [0051]    While the technology disclosed is disclosed by reference to the preferred embodiments and examples detailed above, it is to be understood that these examples are intended in an illustrative rather than in a limiting sense. It is contemplated that modifications and combinations will readily occur to those skilled in the art, which modifications and combinations will be within the spirit of the invention and the scope of the following claims.