Storage module for storing a data file and providing its hash

Abstract

The application relates to a computing device comprising one or more processors and one or more memory devices having stored thereon computer readable instructions which, when executed by the one or more processors, cause the computing device to establish a storage module for storing a data file. The storage module is configured to: load a data file from a data source into the storage module; compute a hash value of the data file loaded into the storage module and make said hash value available to a hash value consumer; grant read-only access to data consumer(s) for accessing said data file loaded into the storage module. The storage module is further configured to detect any change and/or attempted change of the data file and terminate all data consumers which have been granted access to the data file.

Claims

1. A computing device comprising one or more processors and one or more memory devices having stored thereon computer readable instructions which, when executed by the one or more processors, cause the computing device to establish a storage module for storing a data file, the storage module being configured to: load a data file from a data source into the storage module; compute a hash value of the data file loaded into the storage module and make said hash value available to a hash value consumer; establish a server-client dependency relationship with one or more data consumer(s), the storage module being a server and the one or more data consumer(s) being client(s) dependent on the server; grant read-only access to the one or more data consumer(s) for accessing said data file loaded into the storage module; and terminate the server upon detecting any change and/or attempted change of the data file, propagating termination to each of its dependent clients, terminating all data consumers which have been granted access to the data file.

2. The computing device according to claim 1, wherein the storage module is configured to prevent any further loading of a data file, the storage module being restarted before a data file can be loaded again, wherein restarting the storage module causes any data file to be permanently erased from the storage module.

3. The computing device according to claim 1, wherein the storage module is configured to detect any attempted change of the data file by identifying any Read into Memory instructions received by the storage module.

4. The computing device according to claim 1, wherein: loading a data file from a data source into the storage module comprises loading in the storage module a reference to the data file as stored at the data source; and the storage module is configured to detect any change of the data file by computing a hash value of the data file as stored at the data source and comparing it with the hash value of the data file loaded into the storage module.

5. The computing device according to claim 1, wherein the storage module is further configured to grant read-only access to the one or more data consumer(s) for accessing said data file only after the hash value consumer has accessed the hash value.

6. The computing device according to claim 1, wherein: the data file comprises application code; the data consumer is an execution engine of a trusted execution environment; and the hash value consumer is a management module of the trusted execution environment.

7. A computer implemented method for storing a data file on a storage module of a computing device, comprising: loading, by the storage module, a data file from a data source into the storage module; computing, by the storage module, a hash value of the data file loaded into the storage module; making, by the storage module, said hash value available to a hash value consumer; establishing, by the storage module, a server-client dependency relationship with one or more data consumer(s), the storage module being a server and the one or more data consumer(s) being client(s) dependent on the server; granting, by the storage module, read-only access to the data consumer(s) for accessing said data file loaded into the storage module; and terminating the server upon detecting, by the storage module, any change and/or attempted change of the data file, propagating termination to each of its dependent clients, terminating all data consumers which have been granted access to the data file.

8. The method according to claim 7, further comprising: preventing the storage module from any further loading of a data file; restarting the storage module before a data file can be loaded again, wherein restarting the storage module comprises any data file to be permanently erased from the storage module.

9. The method according to claim 7, further comprising identifying, by the storage module, any Read into Memory instructions received by the storage module in order to detect any attempted change of the data file.

10. The method according to claim 7, further comprising: computing, by the storage module, a hash value of the data file as stored at the data source; and comparing, by the storage module, the hash value of the data file as stored at the data source with the hash value of the data file loaded into the storage module in order to detect any change of the data file.

11. The method according to claim 7, wherein read-only access is granted, by the storage module, to the data consumer(s) for accessing said data file only after the hash value consumer has accessed the hash value.

12. The method according to claim 7, wherein: the data file comprises application code; the data consumer is an execution engine of a trusted execution environment; and the hash value consumer is a management module of the trusted execution environment.

13. A computer program product comprising computer-executable instructions which, when executed by one or more processors of a computing device causes the computing device to perform a method comprising: loading, by a storage module of the computing device, a data file from a data source into the storage module; computing, by the storage module, a hash value of the data file loaded into the storage module; making, by the storage module, said hash value available to a hash value consumer; establishing, by the storage module, a server-client dependency relationship with one or more data consumer(s), the storage module being a server and the one or more data consumer(s) being client(s) dependent on the server; granting, by the storage module, read-only access to data consumer(s) for accessing said data file loaded into the storage module; detecting, by the storage module, any change and/or attempted change of the data file; and terminating the server upon detecting, by the storage module, any change and/or attempted change of the data file, propagating termination to each of its dependent clients, terminating all data consumers which have been granted access to the data file.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will be explained in more detail, by way of example, with reference to the drawings in which:

(2) FIG. 1: shows a highly schematic block diagram of a computing device comprising a processor and a memory device;

(3) FIG. 2: shows a schematic block diagram of a trusted execution environment according to the present disclosure;

(4) FIG. 3: shows a schematic block diagram of a trusted execution environment according to the present disclosure;

(5) FIG. 4: shows a schematic block diagram of a trusted execution platform according to the present disclosure;

(6) FIG. 5: shows a sequence diagram of a method of operating a trusted execution environment according to the present disclosure;

(7) FIG. 6: shows a further sequence diagram of a method of operating a trusted execution environment according to the present disclosure;

(8) FIG. 7: shows a further sequence diagram of the method of operating a trusted execution environment according to the present disclosure, wherein an execution timeout leads to a failed execution;

(9) FIG. 8: shows a sequence diagram of a method for storing a data file on a storage module according to the present invention;

(10) FIG. 9: shows a sequence diagram of a further method of operating a trusted execution environment according to the present invention;

(11) FIG. 10: shows a block diagram of a computing environment comprising a plurality of components and a plurality of dependency relationships between the plurality of components;

(12) FIG. 11: shows a flowchart illustrating a method of attesting a state of a computing environment, according to the present disclosure;

(13) FIG. 12: shows a directed acyclic graph used for attesting a state of a computing environment, according to the present disclosure;

(14) FIG. 13: shows a flowchart illustrating a method of attesting a state of a computing environment as well as determining whether integrity of the computing environment has been compromised, according to the present disclosure;

(15) FIG. 14: shows a flowchart illustrating a method of attesting a state of a computing environment, determining whether integrity of the computing environment has been compromised as well as identifying a compromised component and/or dependency, according to the present disclosure; and

(16) FIG. 15: shows a sequence diagram of a further method of operating a trusted execution environment according to the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

(17) FIG. 1 shows a highly schematic block diagram of a generic computing device 1 comprising a processor 2 and a memory device 3. The memory device 3 has stored thereon computer readable instructions which, when executed by the one or more processors 2, cause the computing device 1 to establish a trusted execution environment 100 as shall be described with reference to FIGS. 2 and 3.

(18) FIG. 2 shows a schematic block diagram of the trusted execution environment 100 according to the present invention. In summary, a trusted execution environment 100 is a computing environment which is capable of executing application code and creates a record of that execution called execution record. The trusted execution environment 100 is configured such as to fulfill three properties: Physically and logically secure the execution of the application code from any interference (Isolation Property); Creating an immutable record of the execution of the application code, detailing input, output, time and device state (Audit Property); and Restrict access to start an execution to authorized entities (Authorization Property).

(19) The executed code is provided as an application code and deployed to a storage module 104 of the trusted execution environment 100. The application code is dynamically loaded with each execution request. As illustrated on FIGS. 2 and 3, the storage module 104 provides read-only access to the execution engine 102 for accessing the application code.

(20) A management module 106 of the trusted execution environment 100 is arranged to receive requests for execution by an outside system (hereafter referred to as the requestor), coordinating the execution of the requests sending the response back to the requestor once the execution is finished.

(21) The actual execution of the application code is performed by an execution engine 102 at the instruction of the management module 106.

(22) The execution engine 102 that runs the application code is a separate disposable process isolated from the rest of the computing device. As illustratively shown on FIGS. 2 and 3, all data input, response data output to and from the execution engine 102 is bundled (by the management module 106) into input data stream(s) and output data stream(s), respectively. In addition, according to further embodiments, the execution engine 102 bundles data related to execution status from the execution engine 102 into an execution status report.

(23) Shown on the figures with the label Start and stop, the management module 106 starts and terminates the execution engine 102, the management module 106 being configured to instruct the execution engine 102 to load the application code from the storage module 104 and to execute the application code according to the execution request as well as to terminate the execution engine 102 after execution of the application code.

(24) FIG. 3 shows a schematic block diagram of a trusted execution environment 100 according to the present invention, further comprising an initialization module 105. In summary, the management module 106 delegates the task of initializing the execution engine 102 to the initialization module 105. The initialization module 105 performs the task of initializing the execution engine 102 based on a configuration by the management module 106. This delegation of tasks has the advantage that complexity of the individual modules is reduced. Furthermore, the initialization module 105 is configured to determine a set of dependent resources of the computing device 1 required by the application code for execution and grant the execution engine 102 access rights only to said set of dependent resources (using capability based security). Thereafter, the initialization module 105 instructs the execution engine 102 to load the application code from the storage module 104 and to execute the application code.

(25) According to further embodiments disclosed herein, the computer readable instructions, when executed by the one or more processors 2, further cause the computing device 1 not only to establish a single trusted execution environment 100, but a platform of a plurality of trusted execution environments 100.

(26) FIG. 4 shows a schematic block diagram of a trusted execution platform 200. The trusted execution platform 200 comprises a security monitor 112 established by the computing device 1 and a platform server 114. The security monitor 112 is communicatively connected to the platform server 114 to receive execution requests. The security monitor 112 is configured to initialize a plurality of instances of the trusted execution environment 100 corresponding to the plurality execution requests. A dedicated instance of the trusted execution environment 100 is initialized for each execution request, thereby ensuring an isolated and clean environment for each execution of application code. The security monitor 112 receives execution records corresponding to the execution of the application codes from the management modules 106 of the respective instances of the trusted execution environment 100 and forwards the execution records to the platform server 114.

(27) According to particular embodiments disclosed herein, the security monitor 112 is further configured to dynamically allocate and manage resources of the computing device 1, in particular resources of the one or more processors 2, to the plurality of instances of the trusted execution environment 100. Dynamically allocating and managing resources between the trusted execution environments 100 of the trusted execution platform 200 provides unprecedented flexibility to the trusted execution platform 200 of the present invention, a flexibility that no known implementation of a trusted execution environment is able to provide.

(28) Turning now to FIGS. 5 to 9, methods disclosed herein shall be described with reference to sequence diagrams.

(29) FIG. 5 shows a sequence diagram of a method of operating a trusted execution environment 100 for executing application code.

(30) In a step 10, the management module 106 receives execution request(s) from a requestor to execute the application code. Also as part of step 10, the trusted execution environment 100 is initialized, wherein a storage module 104, a management module 106 as well as an execution engine 102 are provided as part of the trusted execution environment 100.

(31) In a step 30, the storage module 104 provides read-only access to the execution engine 102 for accessing the application code. Thereafter, in a step 40, the management module 106 initializes the execution engine 102 and instructs it to load the application code from the storage module 104. In step 50, the execution engine 102 loads the application code from the storage module 104 as instructed. Then, in step 60, the execution engine 102 executes the application code according to the execution request. In the background, in a step 62, the management module 106 bundles requested data input, response data output to and from the execution engine 102 into input data stream(s) and output data stream(s), respectively.

(32) After execution of the application code, in step 70, the execution engine 102 terminates and reports successful execution to the management module 106. Thereafter, in step 80, the management module 106 creates an execution record of execution of the application code by the execution engine 102 comprising data indicative of said input data stream(s) and output data stream(s). Finally, in step 90, the management module 106 transmits the execution record to the requestor.

(33) FIG. 6 shows a further sequence diagram of a method of operating a trusted execution environment according to the present invention, showing details of how the management module 106 delegates the task of initializing the execution engine 102 to the initialization module 105. In a step 14, the management module 106 configures the initialization module 105. In contrast to the sequence diagram of FIG. 5, in step 40 it is the initialization module 105 that initializes the execution engine 102, based on a configuration by the management module 106. In a step 42, the initialization module 105 determines a set of dependent resources of the computing device 1 required by the application code for execution. Thereafter, in step 44, the initialization module 105 grants the execution engine 102 access rights only to said set of dependent resources.

(34) According to embodiments disclosed herein, granting the execution engine 102 access rights to dependent resources of the computing device 1 required by the application code for execution comprises: determining a set of capabilities required by the execution engine 102, such asbut not limited to: NIC (Network Interface Card) ROM (Read-Only Memory) File system IO Memory (Input Output Memory) RAM (Random Access Memory) Real-time Clock Timer requesting access token(s) corresponding to said set of capabilities from resources possessing said capabilities; and granting access rights for the execution engine 102 to resources of the computing device 1 according said access token(s).

(35) This security model is referred to as capability-based security and is advantageous since the attack surface of a specific component is limited to the bare minimum. A capability is defined to be a protected object reference which, by virtue of its possession by a user process (e.g. the execution engine), grants that process the capability to access with an object in certain ways, such as reading data associated with an object, modifying the object, executing the data in the object as a process, and other conceivable access rights. The capability logically comprises a reference that uniquely identifies a particular object (resource) and a set of one or more access rights.

(36) Also shown on FIG. 6 is step 16, whereinbefore providing access to the application code, the storage module 104 computes a hash value of the application code and provides said hash value to the management module 106. Accordingly, the management module 106 further includes said hash value into the execution record of the respective application code. Hence, an immutable record of the execution of the application is created.

(37) As shown in the sequence of steps 70, 71, the task of monitoring the termination of the execution engine 102 is also delegated to the initialization module 105. Overall, the delegation of tasks (by the management module 106 to the initialization module 105) has the advantage that complexity of the individual modules is reduced.

(38) FIG. 7 shows a further sequence diagram of the method of operating a trusted execution environment 100, wherein an execution timeout/or a resource overuse leads to a failed execution. As illustrated, in a step 63, the initialization module 105 monitors the resource consumption and execution status report of the execution engine 102. In case of an execution timeout and/or a resource overusein a step 71the initialization module 105 reports the execution timeout and/or resource overuse to the management module 106, whichin a step 72instructs the initialization module 105 to cleanup the subsystem, namely the execution engine 102. Thereafterin a step 73the initialization module 105 terminates the execution engine 102. An execution timeout occurs when the execution engine 102 has been executing the application code for a period longer than a timeout defined for the completion of the execution. A resource overuse occurs, when the execution engine 102 uses and/or attempts to use more resources than allocated by the initialization module 105. After the execution engine 102 being terminated earlyin step 73the response by the management module 106 to the security monitor 112 comprises data indicative of the reason for the termination of the execution engine 102.

(39) FIG. 8 shows a sequence diagram of a method for storing a data file on a storage module 104 according to the present invention.

(40) In step 11, the storage module 104 detects any change and/or attempted change of the data file. According to various embodiments disclosed herein, there are different ways to detect a change and/or attempted change of the data file. According to one embodiment, the storage module 104 detects an attempted change of the data file by identifying any Read into Memory instructions received by the storage module 104. Since a data file can only be loaded into the storage module 104 by such an instruction, this mechanism allows detection of any attempt to change the data file.

(41) According to an another embodiment, the storage module 104 is configured to detect a change of the source data file (as stored at the data source) by computing a hash value of the data file as stored at the data store and comparing it with the hash value of the data file loaded into the storage module 104.

(42) If the storage module 104 detects that the data file changed and/or there was an attempt to change the data file, in step 12, the storage module 104 terminates all data consumers which have been granted access to the data file. Furthermore, in step 13the storage module 104 restarts itself upon detection of a change and/or attempted change of the data file. Only after restarting does the storage module 104 allow another data file to be loaded. Restarting the storage module 104 leads to any data file to be permanently erased from the storage module 104.

(43) While the steps 11 to 13 are shown on the figures at a particular phase of the sequence illustrated on the sequence diagram, it must be emphasized, that the storage module 104 continuously monitors whether the data file has changed/whether there has been an attempt to change the data file, and initiates steps 12 and 13 accordingly. It is also to be noted, that there is a need to monitor whether the data file has changed on the data source when the application data is loaded onto the storage module 104 as a reference to the data source.

(44) After the storage module 104 has been initializedin a step 15a data file is loaded from a data source into the storage module 104. In particular, the data file is loaded into the storage module 104, in that a Read into Memory instruction is sent to the storage module 104, with a path/reference of the data file passed on as a parameter of the Read into Memory instruction. According to embodiments disclosed herein, the data source is a file system (physical or virtual) or a network connected data source, such as a remote data storage (e.g. referenced by a network path). Alternatively, or additionally, the data source may be a database, such as a relational database or the like.

(45) After the data file has been loaded into the storage module 104, in step 16, the storage module 104 computes a hash value of the data file. It is important to note that the hash value of the data file as loaded into the storage module 104 is calculated and not a hash value of the data file on the data source. Thereafter, in a step 17, the storage module 104 makes the hash value available to a hash value consumer. The hash value is computed using a known hashing algorithm, such asbut not limited toSecure Hash Algorithms SHA-0 to 3.

(46) The storage module 104 as described herein is referred to as a load-once hashing ROM.

(47) As illustrated on FIG. 8, according to a particular embodiment disclosed herein, the storage module 104 grants read-only access to the data consumer(s) for accessing the data filestep 30only after the hash value consumer has accessed the hash valuestep 20. This prevents situations where a data consumer would access a data file and not be able to retrieve its hash value because the storage module 104 has been restarted in the meanwhile (e.g. due to an attempted change of the data file). In other words, granting access to the data file only after the hash value consumer has accessed the hash value ensures that data consumers only access data filesstep 50with a hash value being read.

(48) FIG. 9 shows a sequence diagram of a method for operating a trusted execution environment 100 comprising storing a data file on a storage module 104 implemented as a load-once hashing ROM according to one of the embodiments disclosed herein. According to the embodiments of the method illustrated in FIG. 9, the data file loaded onto the storage module 104 comprises application code; the data consumer is an execution engine 102 of a trusted execution environment 100; and the hash value consumer is a management module 106 of the trusted execution environment 100.

(49) In step 10, the management module 106 receives execution request(s) from a requestor to execute the application code. Also as part of step 10, the trusted execution environment 100 is initialized, wherein a storage module 104, a management module 106 as well as an execution engine are provided as part of the trusted execution environment 100.

(50) In step 11, the storage module 104 detects any change and/or attempted change of the data file. If the storage module 104 detects that the data file changed and/or there was an attempt to change the data file, in step 12, the storage module 104 terminates all execution engines 102 which have been granted access to the data file. Furthermore, in step 13the storage module 104 restarts itself upon detection of a change and/or attempted change of the data file. Only after restarting does the storage module 104 allow another data file to be loaded. Restarting the storage module 104 leads to any data file to be permanently erased from the storage module 104.

(51) In step 14, the management module 106 configures the initialization module 105. Thereafter, the initialization module 105 initializes the execution engine 102, based on a configuration by the management module 106.

(52) After the storage module 104 has been initializedin a step 15a data file is loaded from a data source into the storage module 104.

(53) After the data file has been loaded into the storage module 104, in step 16, the storage module 104 computes a hash value of the data file. Thereafter, in a step 17, the storage module 104 makes the hash value available to the management module 106 of the trusted execution environment 100. Once the management module 106 determines/is notifiedin step 19that the storage module 104 has been started, the management module 106 loads the hash value from the storage module 104.

(54) In step 30the storage module 104 grants the execution engine 102 read-only access for accessing the data file.

(55) After the management module 106 has loaded the hash value, the management module 106 starts the initialization engine 105in step 31. Thereafter, in a step 40, the initialization engine 105 initializes the execution engine 102 and instructs it to load the application code from the storage module 104.

(56) In step 42, the initialization module 105 determines a set of dependent resources of the computing device 1 required by the application code for execution. Thereafter, in step 44, the initialization module 105 grants the execution engine 102 access rights only to said set of dependent resources.

(57) In step 50, the execution engine 102 loads the application code from the storage module 104 as instructed. Then, in step 60, the execution engine 102 executes the application code according to the execution request. In the background, in a step 62, the management module 106 bundles requested data input, response data output to and from the execution engine 102 into input data stream(s) and output data stream(s), respectively.

(58) After execution of the application code, in step 70, the initialization module 105 is notified of the successful termination of the execution engine 102 andin step 71notifies the management module 106 that the execution was successful. Thereafter, in step 80, the management module 106 creates the execution record of execution of the application code by the execution engine 102 comprising data indicative of said input data stream(s) and output data stream(s) as well as the hash value. Finally, in step 90, the management module 106 transmits the execution record to the security monitor 112.

(59) FIG. 10 shows a block diagram of a computing environment comprising a plurality of components and a plurality of dependency relationships between the plurality of components. The illustrative example shown on FIG. 10 comprises four components, namely Parent, Sibling_1, Sibling_2 and Child_3. Furthermore, FIG. 10 shows two different types of dependency relationships between the plurality of components, namely: parent-child dependencies: ParentSibling_1: Indicative that Parent component is able to spawn child component Sibling_1 ParentSibling_2: Indicative that Parent component is able to spawn and terminate child component Sibling_2 Sibling_2Child_3: Indicative that Sibling_2 component is able to spawn child component Child_3 client-server dependency: Sibling_2 is a server component that provides a service. Sibling_1 connects to that service, and thus is dependent of Sibling_2 in the client-server relationship.

(60) FIG. 11 shows a flowchart illustrating a method of attesting a state of a computing environment, according to the present invention. The method comprises two major steps:

(61) Step A) generating a directed acyclic graph comprising a plurality of nodes and a plurality of directed edges connecting the nodes; and

(62) Step B) generating an attest of the state of the computing environment using the directed acyclic graph.

(63) Step A) comprises several substeps. Within substep A1), a node is associated with each component of the computing environment. Since nodes of a graph each have a so-called name or label and a value, the association of a node with a component may be performed by labelling/naming the node with a component ID. Nodes associated with a component of the computing environment are referred to as component nodes.

(64) Within substep A2), a node is associated with each dependency relationship, such as by labelling/naming the node with a relationship ID. Nodes associated with a dependency relationship are referred to as dependency nodes. Furthermore, each dependency node is assigned with a hash value of data descriptive of said dependency relationship, such as an XML element. Since nodes of a graph each have one or more value fields (in addition to a name/label), the assignment of a node with a hash value may be performed by recording the hash value as a value field of the respective node.

(65) The data descriptive of a dependency relationship comprises at least: data identifying each component included in the dependency relationship (such as a component ID, a component reference or the like) and data identifying the dependee and depender components of the dependency relationship.

(66) Within substep A3), each node associated with a dependency relationship (each dependency node) is connected, using a directed edge, to node(s) associated with component(s) (component node) included in the respective dependency relationship (either as depender or dependee). As used in the context of the present application, a subnode refers to a node A of a graph that is connected to another node B using a directed edge, the edge being directed from node B towards node A.

(67) According to a particular embodiment of the present invention, such as the one illustrated on the figures, the directed edges, connecting nodes associated with parent-child dependencies to nodes associated with components included in the respective dependency relationship: are directed from a component node associated with the dependee towards the dependency node associated with the respective dependency relationship; are directed from a dependency node associated with the respective dependency relationship towards a component node associated with the depender.

(68) On the other hand, the directed edges, connecting nodes associated with other types of dependencies (not parent-child dependencies) to nodes associated with components included in the respective dependency relationship are only directed from a node associated with the dependee of the respective dependency relationship towards the node associated with the respective dependency relationship. According to particular embodiments, in order to ensure that the graph is acyclic, for dependency types other than parent-child dependencies, there is no edge connecting the depender.

(69) Within step A4), each node is assigned with a hash value of all of its subnodes. In particular, each node is assigned with a hash value of the concatenation of the hash values of all subnodes, wherein the hash of a node comprises a hash value of its name/label and data fields.

(70) Within Step B), an attest of the state of the computing environment is generated using the directed acyclic graph. An attest of the state of the computing environment comprises any suitable representation of the directed acyclic graph generated in step A), such asbut not limited toEdge lists, Adjacency matrices and/or Adjacency lists.

(71) FIG. 12 shows the directed acyclic graph corresponding to the computing environment depicted on FIG. 10, as generated according to the present invention. As shown in this figure, each component of the computing environment, namely Parent, Sibling_1, Sibling_2 and Child_3 is associated with a node of the graph, in particular a component node (shown with a solid white rounded rectangle).

(72) Each dependency relationship is associated with a dependency node (shown with a solid grey rounded rectangle), namely: Software package/binary/library dependencies between each component and its underlying sw package (e.g. executable binaries), labeled Hash: Package. Parent-child dependencies: A dependency node labeled Hash: Children, connected as a subnode to the node Hash: Parent. The dependency node labeled Hash: Children comprises a hash value of data descriptive of all children of the component Parent and a hash value of all of its subnodes, namely the hash values of Sibling_1 and Sibling_2. A dependency node labeled Hash: Children, connected as a subnode to the node Hash: Sibling_2. The dependency node labeled Hash: Children comprises a hash value of data descriptive of all children of the component Sibling_2 and a hash value of all of its subnodes, namely the hash value of Child_3. Client-server dependency: Since it is the client that is aware of what services of which servers it consumes (and not the other way around), the node associated with the client-server dependency is connected with a directed edge to the node associated with the server component, labeled Hash: Route_to_sibling_2.

(73) Below is a section of an XML file representative of the directed acyclic graph of FIG. 12 and corresponding to the computing environment of FIG. 10:

(74) TABLE-US-00001 <component name=Computing environment hash=080eaea6de3eff62b86631b31f75d2fd> <component name=Parent hash=180eaea6de3eff62b86631b31f75d2fd> <package name=Parent_1.05.pkg hash=280eaea6de3eff62b86631b31f75d2fd> <binary name=parent_1.05.bin hash=380eaea6de3eff62b86631b31f75d2fd> </binary> <library name=stdlib.so hash=480eaea6de3eff62b86631b31f75d2fd> </library> </package> <children name=children hash=580eaea6de3eff62b86631b31f75d2fd> <component name=Sibling_1 hash=680eaea6de3eff62b86631b31f75d2fd> <package name=Sibling_v1.2.pkg hash=780eaea6de3eff62b86631b31f75d2fd> </package> <routes name=routes hash=880eaea6de3eff62b86631b31f75d2fd> <service name=NIC hash=980eaea6de3eff62b86631b31f75d2fd> Sibling_2 </service> </routes> </component> <component name=Sibling_2 hash=a80eaea6de3eff62b86631b31f75d2fd> <package name=Sibling_v2.2.pkg hash=b80eaea6de3eff62b86631b31f75d2fd> </package> <children name=children hash=c80eaea6de3eff62b86631b31f75d2fd> <component name=Child_3 hash=d80eaea6de3eff62b86631b31f75d2fd> <package name=Child_v1.0.pkg hash=e80eaea6de3eff62b86631b31f75d2fd> </package> </component> </children> </component> </children> </component> </component>

(75) FIG. 13 shows a flowchart illustrating a method of attesting a state of a computing environment as well as determiningin a step C) whether integrity of the computing environment has been compromised by detecting a change in the hash value(s) associated with any node of the directed acyclic graph. Since all components and all dependency relationships are captured by the graph, detecting a change in the hash value(s) associated with any node provides a robust method of determining a change of the computing environment as a whole.

(76) FIG. 14 shows a flowchart illustrating a method of attesting a state of a computing environment. As shown on this figure, in addition to determining whether integrity of the computing environment has been compromised, compromised component(s) and dependency(s) are identified in steps D) and E), respectively. Within step D), a compromised component is identified by finding the node, assigned to said component, with a changed hash value. Within step E), a compromised dependency relationship is identified by finding the node, assigned to said dependency relationship, with a changed ash value.

(77) FIG. 15 shows a sequence diagram of a further method of operating a trusted execution environment according to the present disclosure. In addition to the steps as described in relation with FIG. 9, the method as illustrated on FIG. 15 further comprises step 81, wherein the security monitor 112 captures and attests the state of the trusted execution environment 100, in particular using a directed acyclic graph according to any of the herein described embodiments of the method of attesting a state of a computing environment.

(78) It should be noted that, in the description, the computer program code has been associated with specific processors and the sequence of the steps has been presented in a specific order, one skilled in the art will understand, however, that the computer program code may be structured differently and that the order of at least some of the steps could be altered, without deviating from the scope of the invention.

(79) Further disclosed and proposed are: A data processing apparatus/device/network/system comprising means for carrying out one or more method steps according to embodiments of a method disclosed herein. A data processing apparatus/device/network/system comprising a processor for carrying out one or more method steps according to embodiments of a method disclosed herein. A computer program product comprising computer-executable instructions which, when executed by a data processing apparatus/device/network/system, cause the data processing apparatus/device/network/system to carry out one or more method steps according to embodiments of a method disclosed herein. Computer-readable media, comprising volatile and/or non-volatile storage media (such as a data carrier) and/or transmission media (such as a data carrier signal), comprising computer-executable instructions which, when executed by a data processing apparatus/device/network/system, cause the data processing apparatus/device/network/system to carry out one or more method steps according to embodiments of a method disclosed herein. A computer readable data structure comprising computer-executable instructions which, when executed by a data processing apparatus/device/network/system, cause the data processing apparatus/device/network/system to carry out one or more method steps according to embodiments of a method disclosed herein.

(80) Disclosed herein is a 1. aspect of a computing device 1 comprising one or more processors 2 and one or more memory devices 3 having stored thereon computer readable instructions which, when executed by the one or more processors 2, cause the computing device 1 to establish a trusted execution environment 100 for executing application code, the trusted execution environment 100 comprising: an execution engine 102 configured to execute application code; a storage module 104 configured to provide read-only access to the execution engine 102 for accessing the application code; and a management module 106 configured to: receive, from a requestor, execution request(s) to execute the application code; instruct the execution engine 102 to load the application code from the storage module 104 and to execute the application code according to the execution request; bundle data input, response data output to and from the execution engine 102 into input data stream(s) and output data stream(s), respectively; terminate the execution engine 102 after execution of the application code; create an execution record of execution of the application code by the execution engine 102 comprising data indicative of said input data stream(s) and output data stream(s); and transmit the execution record to the requestor.

(81) Further disclosed herein is a 2. aspect of a computing device 1 according to aspect 1, wherein the trusted execution environment 100 further comprises an initialization module 105 created by the management module 106, the initialization module 105 being configured to initialize the execution engine 102 by: starting the execution engine 102 in accordance with a configuration received from the management module 106; determining a set of dependent resources of the computing device 1 required by the application code for execution; granting the execution engine 102 access rights only to said set of dependent resources; and instructing the execution engine 102 to load the application code from the storage module 104 and to execute the application code.

(82) Further disclosed herein is a 3. aspect of a computing device 1 according to aspect 2, wherein granting the execution engine 102 access rights only to dependent resources of the computing device 1 required by the application code for execution comprises: determining a set of capabilities required by the execution engine 102; requesting access token(s) corresponding to said set of capabilities from resources possessing said capabilities; and granting access rights for the execution engine 102 to resources of the computing device 1 according said access token(s).

(83) Further disclosed herein is a 4. aspect of a computing device 1 according to one of the preceding aspects, wherein the management module 106 is further configured to: include execution status data from the execution engine 102 via the initialization module 105 into the execution record; and terminate the instance of the execution engine 102 if the execution status data comprises data warranting termination.

(84) Further disclosed herein is a 5. aspect of a computing device 1 according to one of the preceding aspects, wherein: the storage module 104 is further configured to compute a hash value of the application code and provide said hash value to the management module 106; and the management module 106 is further configured to include said hash value into the execution record.

(85) Further disclosed herein is a 6. aspect of a computing device 1 according to one of the preceding aspects, wherein the computer readable instructions, when executed by the one or more processors 2, further cause the computing device 1 to establish a security monitor 112, the security monitor 112 being configured to: receive a plurality of execution requests from a platform server 114, the execution requests each comprising authentication data and application code to be executed; authenticate execution requests by verifying said authentication data of the execution requests; upon successful authentication of the execution requests: initialize a plurality of instances of the trusted execution environment 100 corresponding to said plurality execution requests; forwarding each execution request to the management module 106 of the respective instance of the trusted execution environment 100; forwarding each application code to the storage module 104 of the respective instance of the trusted execution environment 100; receiving execution records corresponding to the execution of the application codes from the management modules 106 of the respective instances of the trusted execution environment 100; and forwarding the execution records to the platform server 114.

(86) Further disclosed herein is a 7. aspect of a computing device 1 according to aspect 6, wherein the security monitor 112 is further configured to dynamically allocate and manage resources of the computing device 1, in particular resources of the one or more processors 2, to the plurality of instances of the trusted execution environment 100.

(87) Further disclosed herein is an 8. aspect of a computing device 1 according to aspect 6 or 7, wherein the security monitor 112 is configured to: to digitally sign the execution record with an attestation key; and/or capture and attest data indicative of a platform state, in particular a directed acyclic graph, related to the execution of the application code by the trusted execution environment 100.

(88) Further disclosed herein is a 9. aspect of a computer implemented method of operating a trusted execution environment 100, the method comprising: initializing an execution engine 102 as part of the trusted execution environment 100 and configuring said execution engine 102 for executing application code; providing a storage module 104 as part of the trusted execution environment 100, the storage module 104 being configured to provide read-only access to the execution engine 102 for accessing the application code; providing a management module 106 as part of the trusted execution environment 100; the management module 106 receiving execution request(s) from a requestor to execute the application code; the management module 106 instructing the execution engine 102 to load the application code from the storage module 104 and to execute the application code according to the execution request; the management module 106 bundling requested data input, response data output to and from the execution engine 102 into input data stream(s) and output data stream(s), respectively; the management module 106 terminating the execution engine 102 after execution of the application code; the management module 106 creating an execution record of execution of the application code by the execution engine 102 comprising data indicative of said input data stream(s) and output data stream(s); and the management module 106 transmitting the execution record to the requestor.

(89) Further disclosed herein is a 10. aspect of a method according to aspect 9 further comprising: the management module 106 configuring an initialization module 105: the initialization module 105 starting the execution engine 102 in accordance with a configuration received from the management module 106; the initialization module 105 determining a set of dependent resources of the computing device 1 required by the application code for execution; the initialization module 105 granting the execution engine 102 access rights only to said set of dependent resources; and the initialization module 105 instructing the execution engine 102 to load the application code from the storage module 104 and to execute the application code.

(90) Further disclosed herein is an 11. aspect of a method according to aspect 10, wherein granting the execution engine 102 access rights only to dependent resources of the computing device 1 required by the application code for execution comprises: determining a set of capabilities required by the execution engine 102; requesting access token(s) corresponding to said set of capabilities from resources possessing said capabilities; and granting access rights for the execution engine 102 to resources of the computing device 1 according said access token(s).

(91) Further disclosed herein is a 12. aspect of a method according to one of the aspects 9 to 11, further comprising: including, by the management module 106, execution status data from the execution engine 102 via the initialization module 105 into the execution report; and terminating the instance of the execution engine 102, by the management module 106, if the execution status data comprises status data warranting termination.

(92) Further disclosed herein is a 13. aspect of a method according to one of the aspects 9 to 12, further comprising: the storage module 104 computing a hash value of the application code and provide said hash value to the management module 106; and the management module 106 including said hash value into the execution record.

(93) Further disclosed herein is a 14. aspect of a method according to one of the aspects 9 to 13, further comprising: establishing a security monitor 112 as part of the trusted execution environment 100; the security monitor 112 receiving a plurality of execution requests from a platform server 114, the execution requests each comprising authentication data and application code to be executed; the security monitor 112 authenticating execution requests by verifying said authentication data of the execution requests; and the security monitor 112, upon successful authentication of the execution requests: initialize a plurality of instances of the trusted execution environment 100 corresponding to said plurality execution requests; forwarding each execution request to the management module 106 of the respective instance of the trusted execution environment 100; forwarding each application code to the storage module 104 of the respective instance of the trusted execution environment 100; receiving execution records corresponding to the execution of the application codes from the management modules 106 of the respective instances of the trusted execution environment 100; and forwarding the execution records to the platform server 114.

(94) Further disclosed herein is a 15. aspect of a method according to aspect 14, further comprising dynamically allocating and managing resources of the computing device 1, in particular resources of the one or more processors 2, to the plurality of instances of the trusted execution environment 100.

(95) Further disclosed herein is a 16. aspect of a method according to one of the aspects 9 to 15, further comprising digitally signing the execution record with an attestation key; and/or capturing and attesting data indicative of a platform state, in particular comprising a DAG, related to the execution of the application code by the trusted execution environment 100.

(96) Further disclosed herein is a 17. aspect of a computer program product comprising computer-executable instructions which, when executed by one or more processors 2 of a computing device 1 causes the computing device 1 to carry out the method according to one of the aspects 9 to 16.

(97) Further disclosed herein is a 1. aspect of a computer implemented method of attesting a state of a computing environment comprising a plurality of components and a plurality of dependency relationships between the plurality of components, the method comprising: A) generating a directed acyclic graph comprising a plurality of nodes and a plurality of directed edges connecting the nodes, comprising; A1) associating a node with each component of the computing environment; A2) associating a node with each dependency relationship and assigning the node with a hash value of data descriptive of said dependency relationship; A3) connecting, using directed edges, each node associated with a dependency relationship to a node(s) associated with a component(s) included in the respective dependency relationship; A4) assigning each node with a hash value of all of its subnodes; B) generating an attest of the state of the computing environment using the directed acyclic graph.

(98) Further disclosed herein is a 2. aspect of the method according to aspect 1, wherein data descriptive of a dependency relationship comprises at least: data identifying each component included in the dependency relationship; and data identifying the dependee and depender components of the dependency relationship.

(99) Further disclosed herein is a 3. aspect of the method according to aspect 2, wherein, the directed edges, connecting node(s) associated with a dependency relationship to node(s) associated with component(s) included in the respective dependency relationship: are directed from a node associated with the dependee of the respective dependency relationship towards the node associated with the respective dependency relationship; and/or are directed from a node associated with the respective dependency relationship towards a node associated with the depender of the respective dependency relationship.

(100) Further disclosed herein is a 4. aspect of the method according to aspect 2 or 3, wherein said set of dependency relationships comprise one or more dependency relationship types: parent-child dependency(s), wherein a parent-child dependency(s) is indicative of a child component being spawned by a parent component, the child component being the depender and the parent component being the dependee; and/or client-server dependency(s), wherein a client-server dependency is indicative that a client component consumes a service(s) provided by a server component, the client component being the depender and the server component being the dependee and wherein the data descriptive of the client-server dependency(s) further comprises data identifying the service(s) of the server component consumed by the client component; and/or software package/binary/library dependency(s), wherein a software package/binary/library dependency is indicative that, when executing, a component executes computer-readable instructions comprised by a software package and/or library.

(101) Further disclosed herein is a 5. aspect of the method according to one of the preceding aspects, further comprising: C) determining whether integrity of the computing environment has been compromised by detecting a change in the hash value(s) associated with any node of the directed acyclic graph.

(102) Further disclosed herein is a 6. aspect of the method according to aspect 5, further comprising the step(s) of: D) identifying a compromised component by finding the node, assigned to said component, with a changed hash value; and/or E) identifying a compromised dependency relationship by finding the node, assigned to said dependency relationship, with a changed hash value.

(103) Further disclosed herein is a 7. aspect of the method according to one of the preceding aspects, wherein the nodes of the directed acyclic graph are further associated with a hash value of: binary(s) used to execute the respective component; and/or dynamic library(s) used to execute the respective component; and/or source code of the respective component; and/or source code of the software library(s); and/or raw data file(s); and/or a compiler(s) that has been used to compile said source code of the respective component into computer-readable instructions executed within the respective component.

(104) Further disclosed herein is an 8. aspect of the method according to one of the preceding aspects, wherein one or more nodes of the directed acyclic graph is further associated with version information for each component and wherein the method further comprises: cross-referencing said version information with a database of vulnerable versions of components and terminating the computing environment running any component whose version information is flagged as unsecure in said database.

(105) Further disclosed herein is a 9. aspect of the method according to aspect 8, further comprising the step of notifying a Security Information and Event Management System (SIEM) about a vulnerability of the computing environment if any component is associated with version information listed in said database of vulnerable versions of components.

(106) Further disclosed herein is a 10. aspect of the method according to one of the preceding aspects, wherein the nodes of the directed acyclic graph are further associated with licensing information for each component and wherein the method further comprises the step of attesting compliancy of the computing environment with a specified licensing requirement by verifying that all nodes associated with a component satisfy said licensing requirement.

(107) Further disclosed herein is an 11. aspect of the method according to one of the preceding aspects, wherein each node is associated with a hash value of the concatenation of the hash values of all subnodes.

(108) Further disclosed herein is a 12. aspect of the method according to one of the preceding aspects, wherein said computing environment is a trusted execution environment 100 comprising an execution engine 102 executing said plurality of components; a management module 106 configured to control a life cycle(s) of the execution engine 102; and a storage module 104 for application code to be executed by component(s) of the execution engine 102

(109) Further disclosed herein is a 13. aspect of the method according to aspect 12, wherein components executed by the execution engine 102 comprise: execution of application code provided for execution to the trusted execution environment 100 by a requestor; and/or components started during execution of said application code according to one or more of said parent-child relationship(s); and/or services started by the execution engine 102 according to one or more of said client-server dependency(s); and/or executable binaries of libraries loaded by the execution engine 102 according to one or more of said software package/binary/library dependency(s).

(110) Further disclosed herein is a computing device 1 comprising one or more processors 2 and one or more memory devices 3 having stored thereon computer readable instructions which, when executed by the one or more processors 2, cause the computing device 1 to carry out the method according to one of the aspects 1 to 13.

(111) Further disclosed herein is a computer program product comprising computer-executable instructions which, when executed by a processor 2 of a computing device 1 causes the computing device 1 to carry out the method according to one of the aspects 1 to 13.

LIST OF REFERENCE NUMERALS

(112) computing device 1 processor 2 memory device 3 trusted execution environment 100 execution engine 102 storage module 104 initialization module 105 management module 106 security monitor 112 platform server 114 trusted execution platform 200

Storage module for storing a data file and providing its hash

Assignee

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Cpc classification

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G06F2206/1014

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G06F3/0655

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G06F3/0679

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G06F21/53

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G11C2216/26

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G06F3/0622

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G06F21/57

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G06F3/0673

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International classification

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G06F21/53

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G06F21/57

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G06F3/06

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Abstract

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Description