Patent Description:
In a network, data packets may be transmitted through one or more network elements (e.g., nodes or routers) before arriving at their destination. For example, data packets may be transmitted through a network that utilizes segment routing (SR) technology. SR may be utilized with both Multi-Protocol Label Switching (SR-MPLS) and Internet Protocol version <NUM> (SRv6) data-planes. In some circumstances, certain network elements of an SR network may become compromised. For example, an attacker may gain control of a router and direct traffic from the router to the attacker's computing device. In the event the attacker gains access to one or more network nodes, the attacker may tamper with the sensitive information transmitted through the compromised node.

An article entitled "<NPL> discloses a method to utilize existing iPv6 protocols that enables destinations to temporarily confer trust on sources, and for trusted traffic to be routed and processed differently from untrusted traffic.

In a communications network, data packets may be transmitted through one or more network elements (e.g., routers) before arriving at their destination. In some networks, Segment Routing (SR) technology is utilized to transmit data packets through a network. Segment routing is typically used on top of either a Multi-Protocol Label Switching (SR-MPLS) network or on top of an Internet Protocol version <NUM> (SRv6) network. In an MPLS network, a header (also known as an MPLS label stack) is used to encode segments of the network. Under IPv6, a header known as a Segment Routing Header (SRH) is used to encoded segments of the network. Segments in an SRH are encoded in a list of IPv6 addresses.

In some situations, certain network elements in an SR network (e.g., an SR-MPLS or an SRv6 network) may become compromised. For example, an attacker may gain control of a router and direct traffic from the router to the attacker's computing device. In the event the attacker gains access to one or more network nodes, the attacker may tamper with the sensitive information transmitted through the compromised node.

To address these and other problems in networks that utilize segment routing, embodiments of the disclosure provide apparatuses, systems, methods, and computer-readable media for applying attestation to SR-MPLS and SRv6. In some embodiments, the attestation that is applied to SR-MPLS and SRv6 includes a token which may allow external entities to validate freshness of asserted data based on the state of internal counters within a Trusted Platform Module (TPM). The token or signed measurement may be referred herein as an attestation or a canary stamp (or simply "stamp") since a token or signed measurement may provide authenticity similar to a stamp and may be used as an early indicator of trouble. In some embodiments, the attestation is applied to SR-MPLS and SRv6 using a new Type/Length/Value (TLV) triplet. The TLV that includes the attestation may be transmitted to other network entities (e.g., other routers in the SR network) via an MPLS label or an IPv6 SRH.

Disclosed herein are, inter alia, methods, apparatus, computer-storage media, mechanisms, and means associated with a SR network element (e.g., router) receiving SR packets, updating SR headers to include an attestation (e.g., canary stamp) of the SR network element, and communicating data packets with the updated SR header that includes the attestation to another SR network element. As used herein, segment routing includes, but is not limited to, SRv6 and SR-MPLS. In some embodiments, headers used in SRv6 and SR-MPLS have been modified to include attestation of traversed network elements. In some embodiments, the attestation is carried in new TLV triplets within headers of SRv6 and SR-MPLS. In some embodiments, an SR router performs a method of applying attestation to SRv6 and SR-MPLS. In some embodiments, an SR endpoint performs a method of applying attestation to SRv6 and SR-MPLS. The included attestation provides verifiable evidence of the trustworthiness of SR network elements, thereby enabling other SR network elements to ascertain if any SR network element has been compromised (e.g., hacked or captured). This increases the security of the SR network and reduces or eliminates the possibility of sensitive information being stolen. These and other embodiments and benefits are discussed in more detail below in reference to the provided figures.

<FIG> illustrates a network <NUM>, according to certain embodiments. As illustrated, network <NUM> includes client networks <NUM> and <NUM> (which may be the same network in some embodiments) external to SR network <NUM>. SR network <NUM> includes SR edge nodes <NUM> and <NUM> and one or more communicatively-coupled network elements <NUM> (e.g., routers, SR gateways, service functions, etc.). In response to receiving a native packet, an SR edge node <NUM>, <NUM> identifies an SR policy (e.g., list of segments) through or to which to forward an SR packet encapsulating the native packet. These policies can change in response to network conditions, network programming, etc. SR edge nodes <NUM> and <NUM> also decapsulate native packets from SR packets and forward the native packets into networks <NUM> and <NUM>.

As used herein, segment routing or "SR" includes, but is not limited to, SRv6 and SR-MPLS. In one embodiment, segments (e.g., SRv6 SIDs or SR-MPLS segments) are advertised by an SR gateway on behalf of one or more service functions. In one embodiment, an SR-MPLS encapsulating header includes an MPLS label stack, with each label (e.g., MPLS SID) in the stack representing a segment. In one embodiment, an SRv6 encapsulating header includes an IPv6 header with an SR extension header containing a list of IPv6 addresses, each representing a segment. These segments are used to forward SR packets through an SR network, including to forward an SR packet to an SR gateway to have one or more services applied to a native packet encapsulated in the SR packet.

As discussed in more detail below, network elements <NUM>-<NUM> of SR network <NUM> apply attestation <NUM> to SR-MPLS and SRv6. In some embodiments, attestation <NUM> includes a token which may allow external entities to validate freshness of asserted data based on the state of internal counters within a TPM. In some embodiments, attestation <NUM> is provided by a TMP. Dedicated crypto-processors, such as a TPM, may take measurements necessary to attest the identity of a device and running binaries on the device. These measurements may include evidence that the device is in a known safe state. However, a receiver must be able to certify the evidence as fresh. Without a guarantee of freshness, an attacker may have an opening to inject previously recorded measurements, asserting what is replayed as being current. When sensitive information is being transmitted to a destination device through a network, network traffic should not be sent through comprised network nodes (e.g., hacked or captured nodes) to prevent leakage of or tampering with the sensitive information. However, traditional protections and link encryption are ineffectual to ensure that each router in the end to end path is not compromised specially when an attacker gains root access to a device via some exploit.

In particular embodiments, a first network node (e.g., SR edge node <NUM>) may be configured to communicate using SR-MPLS or SRv6. SR edge node <NUM> may receive a native data packet from external client network <NUM>. SR edge node <NUM> may add a header to the native data packet in order to transmit the native data packet through SR network <NUM>. In order to verify the security or state of SR edge node <NUM>, SR edge node <NUM> inserts attestation <NUM> within the header added to the native data packet. Attestation <NUM> may be for proving that SR edge node <NUM> is in a known safe state. In some embodiments, other network elements <NUM>-<NUM> may determine that the attestation <NUM> from SR edge node <NUM> is valid at a current time and may compute a trust level for SR edge node <NUM> based at least on the received attestation token <NUM>. The trust level for SR edge node <NUM> may be used by other network elements <NUM>-<NUM> to compute a routing table of the network.

As described herein, verifiable evidence of device tampering (e.g., canary stamps) may be appended to interactions based on existing communication protocols. This may give evidence receivers the option of evaluating trustworthiness of the network device and reacting accordingly. For example, the evidence receiver may determine that it no longer trusts the network device and adjusts network policy to mitigate possible damage or potential security threats. Dedicated crypto-processors such as a TPM may take necessary measurements to attest the identity of a device and its running binaries. These measurements may include detecting evidence which indicates that the device is in a known safe state. However, a receiver may need to certify the evidence as fresh because, without a guarantee of freshness, an attacker may inject previously recorded measurements to make the receiver to assert what is replayed as being current.

Traditional systems and methods may identify or detect the replaying of old evidence via a nonce. For example, a nonce could be a random number provided by the entity making the request. This nonce may be passed into the TPM which may generate results including a signature based on the nonce which could not have been generated without providing that nonce. However, the nonce-based method may rely on the transactional challenge/response interaction model. In other words, the nonce-based method may not work with unidirectional communications originating from the attesting device. For example, a nonce may not work with an asynchronous push, multicast, broadcast messages, etc..

Particular embodiments of this disclosure may perform a unidirectional attestation which is applicable to, for example, an asynchronous push, multicast, broadcast messages, etc., for the authentication of the corresponding devices in conjunction with corresponding binaries. Particular embodiments may enable a communication platform to assess whether the peer platforms are trustworthy. For example, the system may perform a detection of invalid attestations that can trigger alarms/events reduction of network access from a suspect device. The communication platforms may be capable of supporting the unidirectional attestation mechanism. As an alternative approach for attesting freshness, particular embodiments of the system may generate a token which may allow external entities to validate freshness of asserted data based on the state of internal counters within the TPM. The token may allow the replay attacks to be detected without a nonce and make it possible for the attestation for asynchronous push, multicast, broadcast, etc. The token or signed measurement may be referred as a canary stamp since a token or signed measurement may provide authenticity like a stamp and may be used as an indicator of an early sign of trouble. Particular embodiments of the system may combine the token or signed measurement with TPM-integrated capabilities aimed at verifying that valid binary processes are running. The TMP-integrated capabilities may include, for example, but are not limited to, trusted execution environments (TEE) which may provide runtime malware protections and authenticated code modules (ACM) which may ensure that only digitally signed code modules can be loaded into a CPU. Particular embodiments of this disclosure may be implemented within a communication platform (e.g., a proprietary platform) or/and across multiple communication platforms (e.g., proprietary platforms and third-party platforms).

Particular embodiments of the system provide an advantageous technical solution for communication platforms to attest authenticity and allow a common unidirectional attestation framework to be applied across existing networking hardware as well as virtual routers. Particular embodiments of this disclosure may be applicable to, for example, but not limited to, Cisco Secure Boot, Linux Integrity Measurement Architecture (IMA), Intel's Trusted Execution Technology (TXT), etc., and may enable these platforms to validate that a processor is running known software with valid chain of binary signatures. Particular embodiments of the system may provide defining requirements for the placement of different types of signed measurements (e.g., token or stamps) while allowing receivers to evaluate potential trustworthiness of attested information. Particular embodiments of the system may support controller-based evaluation of signed measurement (e.g., token or stamps) which includes subscription-based mechanisms to incrementally push information/evidence to be verified or/and beachhead use cases and platforms.

TPM functionality may be embedded in a wide variety of devices including mobile phones, PCs, routers, etc. While traditional TPM methods may enable a device to prove freshness in a replay to a response, these methods may not support unidirectional attestation. Particular embodiments of this disclosure may provide mechanisms for verifiable unidirectional attestation by creating and distributing a token. This token may link counters on an attesting device with one or more globally verifiable characteristics or parameters (e.g., a counter on a controller, a RADIUS server, or a time authority). Upon its creation, the token may be distributed freely to any number of receivers/verifiers. Upon receiving the token, a receiver may accept subsequently attested information (e.g., stamps) from a remote TPM and attest asynchronous push, multicast, or broadcast communications of a device. It is notable that, in this disclosure, the term "TPM" may be used as an umbrella term for the necessary functionality. The mechanisms described may be supported by one or more proprietary hardware and other hardware supporting the TPMv2 specification.

In particular embodiments, the system may create the initial token by extracting current counters from an attestee's TPM (e.g., either the local network element <NUM> or another network element <NUM>), and hashing it with information from an external TPM. As a result, the system may generate a non-spoofable token which binds continuously incrementing counters on an attestee with some known external state. In particular embodiments, any resetting of the TPM counters may be visible in any subsequent TPM queries. Any restarting of platform may be exposed in subsequent TPM queries. Within these bounds of reset and restart, the TPM's counter time-tick may keep continuous increments. Therefore, the push of attestee TPM information which includes these three counters may be known to have occurred subsequently to any previously received measurement. On the other hand, if the reset and restart counters have not changed, the incremental time since any previous measurement may also be known. In particular embodiments, the system may validate device information asserted from outside the TPM's program configuration registers (PCR). The majority of information needing to be trusted by network peers may not be contained within the TPM's PCR. Particular embodiments of the system may provide indirect methods of validating that a device has not been compromised based on the data or processes of exiting systems or platforms.

A network may only be as secure as its weakest links. Information sent from a first device to a second device on the network may pass through multiple intermediary nodes or devices (e.g., routers, network controllers, etc.) before it reaches the target device. It is vitally important that transmitted information, especially when it includes sensitive material, should not be sent through compromised network nodes (e.g., hacked or captured nodes) to prevent leakage of or tampering with the sensitive information. However, as network size and complexity increase, the potential number of attack vectors for an attacker to exploit also grows. It may be difficult to determine with certainty whether each individual node through which an arbitrary piece of information may pass is secured without having a dramatic effect on the performance of the network. Moreover, if an attacker gains root access to a device (e.g., via some previously undetected exploit), traditional protections and link (e.g., in-transit) encryption may prove ineffectual at protecting any sensitive information.

Particular embodiments may apply attestation in the context of security management at a network-level to determine in real-time whether a node in a network should be trusted. This disclosure introduces an asynchronous, unidirectional time-based variant of attestation that may allow other nodes in a network to reliably ascertain if a source that is routing information has been compromised. As previously discussed, the token used in this variant of attestation may be referred to as a "canary stamp" as it positively marks data as it transitions through the network and can indicate on a front-line basis whether any security problems may exist.

<FIG> illustrates a typical Multiprotocol Label Switching (MPLS) label stack entry <NUM> containing an SR-MPLS Network Programming label, according to certain embodiments. MPLS header label stack entry <NUM> includes a Network programming label that is set to <NUM> bits. An SR-MPLS Network Programming label is allocated from the Segment Routing Global Block (SRGB). The format of an MPLS label stack entry is defined in RFC3032. MPLS header label stack entry <NUM> also includes an EXP field which is a <NUM>-bit Traffic Class field for QoS (quality of service) priority and ECN (Explicit Congestion Notification). MPLS header label stack entry <NUM> also includes a Bottom of Stack (BoS) bit and an <NUM>-bit TTL (time to live) field. For more information on these fields of MPLS header label stack entry <NUM>, please refer to Request for Comments (RFC) <NUM>.

<FIG> illustrate example SR-MPLS network programming headers 300A and 300B that include additional fields such as Type/Length/Value (TLV) triplets, according to certain embodiments. In general, SR-MPLS network programming headers 300A and 300B differ from MPLS header label stack entry <NUM> in that they include extra fields to allow for the transport of additional information through SR network <NUM>. For example, SR-MPLS network programming headers 300A and 300B may be used to transmit and collect attestations <NUM> (e.g., canary stamps) from SR network elements <NUM>-<NUM>. In the illustrated embodiment of <FIG>, SR-MPLS network programming header 300A includes networking programming label, EXP, BoS, and TTL fields as described above in reference to <FIG>. In addition to these fields, SR-MPLS network programming header 300A includes a <NUM>-bit flow label field <NUM>, which is similar to an IPv6 flow label, and an <NUM>-bit next header field <NUM>. Next header field <NUM> identifies the header that directly follows the current SR-MPLS header. Possible values for next header field <NUM> include the following: IPv4, IPv6, and MPLS (indicates that the label stack continues after this header.

SR-MPLS network programming header 300A also includes optional TLV field <NUM>, which may be a variable length and may contain any number of TLV objects. In some embodiments, optional TLV field <NUM> may leverage SRH TLVs. In some embodiments, the number and/or type of TLV objects in optional TLV field <NUM> is carried in the SID semantic associated to the Network Programming label (e.g., label <NUM> could be allocated for "opaque metadata TLV," label <NUM> for "canary stamp TLV" and label <NUM> for "opaque metadata and canary stamp TLVs"). Possible TLVs carried in optional TLV field <NUM> include the following: attestation <NUM>, opaque metadata (sec <NUM>. <NUM> of draft-ietf-spring-sr-service-programming), Network Service Header (NSH) carrier (sec <NUM>. <NUM> of draft-xuclad-spring-sr-service-programming), and in-situ Operations And Maintenance (IOAM). In certain embodiments, a "Total length" field of <NUM> octet may be inserted between next header field <NUM> and the first TLV of TLV field <NUM> such that the SID semantic only needs to express whether or not the SR-MPLS network programming header has TLVs attached to it.

The format for TLVs carried in TLV field <NUM> includes a type field, a length field, and a value field. The type field is typically a binary code that indicates the kind of field that this part of the message represents. In many cases, the type code for each type of TLV may be assigned by the Internet Assigned Numbers Authority (IANA) for interoperability. The length field defines the length of the value field in octets. The TLVs may also include nested TLVs or sub-TLVs. The TLV may be used to carry a variety of types of information. In particular embodiments, a canary stamp may be encoded in SR-MPLS or SRv6 as an attestation-focused TLV, as discussed in more detail herein.

In certain embodiments, SR network elements <NUM>-<NUM> such as an SR-MPLS node include additional capabilities beyond typical SR network elements. For example, some SR network elements include the capability of recognizing a particular label L (e.g., a particular SR-MPLS network programming header 300A) as a metadata label. Once identified as a metadata label, the SR-MPLS node may perform load-balancing based on the flow label and may read the attached TLV(s). If the particular label L is the top label, the SR-MPLS node may pop the network programming header (including L and any attached TLV), then continue the packet processing as per the "Next header" value.

In some embodiments, an SR-MPLS network programming segment is placed at the bottom of the MPLS label stack. If the SR-MPLS network programming segment is not placed at the bottom of the MPLS label stack, the Next header value is set to an appropriate value (e.g., as assigned by IANA) to indicate that more MPLS labels follow.

In some embodiments, an SR-MPLS network programming segment may not be associated with any forwarding equivalence class (FEC). In certain embodiments, when computing a load-balancing hash, the first SR-MPLS network programming segment in the label stack is searched for and, if present, its flow label is included in the load balancing hash. In certain embodiments, when processing a service segment that may benefit from metadata, the first SR-MPLS network programming segment in the label stack is searched for and, if present, relevant information in the attached TLVs is searched for. In certain embodiments, when the SR-MPLS network programming segment is at the top of the label stack, the SR-MPLS network programming header is popped and the remaining data is processed as indicated by the next header field <NUM>.

<FIG> illustrates an example SR-MPLS network programming header 300B, which is a simplified version of SR-MPLS header 300A of <FIG>. The network programming label field of SR-MPLS network programming header 300B may be routed and/or may indicate metadata. In some embodiments, the TLV field of SR-MPLS network programming header 300B may contain a timestamp. In some embodiments, a color bit may be provided in SR-MPLS network programming header 300B.

SR-MPLS network programming headers 300A and 300B provide numerous advantages over traditional MPLS (LDP (RFC5036) or RSVP-TE (RFC3209)) or SR-MPLS (RFC8660). For example, SR-MPLS network programming headers 300A and 300B provide a pure SR solution for MPLS payload identification with no dependency on the Multiprotocol Label Switching Working Group (MPLS WG). In addition, SR-MPLS network programming headers 300A and 300B provide a pure SR solution for load-balancing/entropy with no dependency on MPLS WG. Furthermore, SR-MPLS network programming headers 300A and 300B add metadata carrying capabilities (e.g., canary stamp, service programming, IOAM, etc..

<FIG> illustrates a TLV object <NUM> that can be used as part of the TLV list in either optional TLV field <NUM> of <FIG> or optional TLV field <NUM> of <FIG>, according to certain embodiments. The same TLV object format may be used for both SR-MPLS and SRv6. In certain embodiments, SR network elements <NUM>-<NUM> in SR network <NUM> collect the attestations <NUM> of all SR segment endpoints traversed by a packet during the packet's journey across the network. This collection leverages SR-MPLS network programming headers such as SR-MPLS network programming headers 300A and 300B. To accomplish this, the headend node may insert TLV object <NUM> with an empty stamp collection TLV of the format illustrated in <FIG>. TLV object <NUM> may include a type field <NUM>, a length field <NUM>, an offset field <NUM>, and stamps field <NUM>. In some embodiments, type field <NUM> and length field <NUM> are similar to or identical to corresponding fields in typical TLVs. In some embodiments, the TLV length is set to <NUM> octet plus the size of k canary stamps (and plus any required padding for alignment in some embodiments), where k is the number of SIDs that are expected to be traversed in SR network <NUM>. The number of SIDs that are expected to be traversed may equal the number of SIDs in the pushed SID-list, plus for each Binding-SID in the SID-list, the number of SIDs in the largest SID-list that will be pushed as part of the Binding-SID processing, recursively. A small margin (e.g., <NUM>) may be added for Topology Independent Loop-Free Alternate (TI-LFA). In some embodiments, offset field <NUM> indicates a location within stamps field <NUM> in which to write an attestation <NUM> (e.g., canary stamp). Stamp field <NUM> includes attestations <NUM> from traversed SR network elements <NUM>-<NUM>.

At each SID endpoint, the following packet processing may be performed using TLV object <NUM>. First, the SID endpoint may pop the top label (active segment). The SID endpoint may then look for the stamp collection TLV at the bottom of the label stack. The SID endpoint may retrieve the current offset O from the offset field <NUM>. The SID endpoint may retrieve an attestation <NUM> of the local node and write the local node's attestation <NUM> in stamp field <NUM> at offset O. The SID endpoint may increment the value in offset field <NUM> by the size of one canary stamp and continue the SID processing. As a result, the local node's attestation <NUM> may be transmitted to subsequent SR network elements, and the next SR network element will have the correct location as indicated in offset field <NUM> in which to write its own attestation <NUM>.

<FIG> illustrates a typical IPv6 SRH <NUM>, according to certain embodiments. SRH <NUM> includes fields such as a next header field, a routing type field, a flag field, a tag field <NUM>, and an optional TLV field <NUM>. The fields of SRH <NUM> are defined and described in more detail in the IPv6 Segment Routing Header (SRH) document (draft-ietf-6man-segment-routing-header). As described in more detail below in reference to <FIG>, certain embodiments utilize SRH <NUM> to apply attestation to SRv6.

<FIG> illustrates a method 600A that a router of SR network <NUM> may utilize to apply attestation to SRv6. In general, SRv6 may be used by some embodiments to collect attestation <NUM> for any SR network element along the path in an inband manner. For example, routers in an SRv6 network <NUM> may collect the canary stamps of all routers along the packet path the network. A particular embodiment of a method 600A to support this is described in more detail below. This method allows SR network elements to write canary stamps at deep packet locations.

Method 600A may be performed by any appropriate SR network element (e.g., an SRv6 router) in SR network <NUM> to collect the canary stamp for any router along the path in an inband manner using SRv6. In some embodiments, as a process prior to method 600A, an application maintains an active (open) TCP socket. An agent hooked on the socket inserts every predetermined number of packets (e.g. <NUM>) an SRH with a tag value (e.g., tag field <NUM>) and a large empty TLV (inband packet) (e.g., in TLV field <NUM>). In some embodiments, tag field <NUM> is initially set to zero. Each monitoring-enabled router may be configured with a DSCP matching rule for an OAM bit. Method 600A may then begin in step <NUM> where a data packet is received. Upon receiving a packet in step <NUM>, if the OAM bit is set, then the following actions may be performed. At step <NUM>, method 600A inspects the SRH and retrieves the TLV offset value T from tag field <NUM>. At step <NUM>, method 600A computes the global offset O. In some embodiments, O is computed in step <NUM> as O = C + <NUM> + (LE+<NUM>) * <NUM> + <NUM> + T, where: C is the current packet offset (beginning of the SRH); <NUM> bytes is the length of the fixed SRH fields; LE is the SRH Last Entry value; and <NUM> bytes is the length of the fixed TLV fields.

At step <NUM>, method 600A fetches or generates attestation <NUM> for the local SR network element. At step <NUM>, method 600A writes at offset O (computed in step <NUM>) the node-id of the SR network element (e.g., <NUM> bytes) and the attestation <NUM> for that router (N bytes) from step <NUM>. At step <NUM>, method 600A increments the TLV offset in tag field <NUM> by (<NUM>+N) bytes.

In some embodiments, none of the SR Endpoints that perform method 600A perform PSP. In some embodiments, method 600A may also include writing an interface-id as well as a timestamp in in TLV field <NUM> in order to provide hardware tracing features integrated with the canary stamp.

Particular embodiments may repeat one or more steps of the method of <FIG>, where appropriate. Although this disclosure describes and illustrates particular steps of the method of <FIG> as occurring in a particular order, this disclosure contemplates any suitable steps of the method of <FIG> occurring in any suitable order. Moreover, although this disclosure describes and illustrates an example method for apply attestation to SRv6 including the particular steps of the method of <FIG>, this disclosure contemplates any suitable method for apply attestation to SRv6 including any suitable steps, which may include all, some, or none of the steps of the method of <FIG>, where appropriate. Furthermore, although this disclosure describes and illustrates particular components, devices, or systems carrying out particular steps of the method of <FIG>, this disclosure contemplates any suitable combination of any suitable components, devices, or systems carrying out any suitable steps of the method of <FIG>.

<FIG> illustrates a method 600B that an SR endpoint of SR network <NUM> may utilize to apply attestation to SRv6. In some embodiments, method 600B may be performed by each particular segment endpoint in SR network <NUM> in order to insert a canary stamp for the particular segment endpoint. This method allows SR network elements to write canary stamps at deep packet locations. In some embodiments, as a process prior to method 600B, a source SR node (e.g., router) inserts SRH <NUM> with a new empty TLV. The TLV has the size of N canary stamps, where N is the number of segments in the SRH. Method 600B may then begin in step <NUM> where a data packet is received. At step <NUM>, method 600B determines the current packet offset C, which is the beginning of the SRH. At step <NUM>, method 600B determines the SRH last entry value LE from SRH <NUM>. At step <NUM>, method 600B determines the SRH segment left value SL from SRH <NUM>. At step <NUM>, method 600B fetches or generates attestation <NUM> for the SR endpoint. At step <NUM>, method 600B determines the size of the attestation <NUM> of step <NUM> in bytes. At step <NUM>, method 600B calculates a TLV offset using the current packet offset C of step <NUM>, the SRH last entry value LE of step <NUM>, the SRH segment left value SL from step <NUM>, and the size of the attestation <NUM> of step <NUM>. In some embodiments, the TLV offset O is computed in step <NUM> as O = C + <NUM> + (LE+<NUM>) * <NUM> + <NUM> + (LE-SL)*sizeof(stamp). At step <NUM>, method 600B writes attestation <NUM> for the SR endpoint in SRH <NUM> at the computed TLV offset O calculated in step <NUM>. After step <NUM>, method 600B may end.

<FIG> illustrates a method <NUM> of applying attestation to SR-MPLS, according to certain embodiments. Method <NUM> may begin at step <NUM> where a data packet is received. In some embodiments, the data packet is an SR-MPLS or SRv6 data packet that is received at an SR network element such as a router or SR endpoint. At step <NUM>, method <NUM> accesses or otherwise generates an attestation token. In some embodiments, the attestation token is attestation <NUM>. In some embodiments, the attestation token is generated by a crypto-processor of the local SR network element.

At step <NUM>, method <NUM> determines a location within a header of the received data packet to write the attestation token. In some embodiments, the header is an MPLS header or an IPv6 SRH. In some embodiments, determining a location within a header of the received data packet for the attestation token includes computing a new offset value using an existing offset value stored in the header. In some embodiments, step <NUM> includes the steps described above in reference to step <NUM> of <FIG> or step <NUM> of <FIG>.

At step <NUM>, method <NUM> creates an updated header by encoding the attestation token of step <NUM> in the determined location of the header of step <NUM>. In some embodiments, step <NUM> includes writing the attestation token in a TLV within the header. At step <NUM>, method <NUM> sends the updated header with the encoded attestation token to another apparatus of the SR network. After step <NUM>, method <NUM> may end.

<FIG> illustrates a method <NUM> of applying attestation to the IPv6 hop-by-hop extension header, according to certain embodiments. Method <NUM> may be performed by any appropriate SR network element (e.g., a router) in SR network <NUM> to collect the canary stamp for any router along the path in an inband manner using IPv6. In some embodiments, as a process prior to method <NUM>, an application maintains an active (open) TCP socket. An agent hooked on the socket inserts every predetermined number of packets (e.g. <NUM>) an IPv6 hop-by-hop extension header with an option that includes a large empty TLV. In some embodiments, the hop-by-hop extension header contains the current index (initialized to zero) and an empty canary stamp list that will hold the router-IDs and canary stamps. Method <NUM>, which may be performed by router N, may then begin in step <NUM> where a data packet is received. At step <NUM>, method <NUM> proceeds to IPv6 processing. As part of this process, the router will go through the hop-by-hop extension header according to typical RFC8200 behavior and proceed to process the hop-by-hop extension header in step <NUM>. At step <NUM>, method <NUM> fetches or otherwise generates attestation token <NUM> for itself (router N). At step <NUM>, method <NUM> write the Router-id of itself (router N) and the attestation token <NUM> of step <NUM> at list[current_index]. At step <NUM>, method <NUM> increases the current index and then proceeds with the processing of the remaining extension headers in step <NUM>. After step <NUM>, method <NUM> may end.

Particular embodiments may repeat one or more steps of the method of <FIG>, where appropriate. Although this disclosure describes and illustrates particular steps of the method of <FIG> as occurring in a particular order, this disclosure contemplates any suitable steps of the method of <FIG> occurring in any suitable order. Moreover, although this disclosure describes and illustrates an example method for applying attestation to the IPv6 hop-by-hop extension header including the particular steps of the method of <FIG>, this disclosure contemplates any suitable method for applying attestation to the IPv6 hop-by-hop extension header including any suitable steps, which may include all, some, or none of the steps of the method of <FIG>, where appropriate. Furthermore, although this disclosure describes and illustrates particular components, devices, or systems carrying out particular steps of the method of <FIG>, this disclosure contemplates any suitable combination of any suitable components, devices, or systems carrying out any suitable steps of the method of <FIG>.

<FIG> illustrates an example computer system <NUM>. In particular embodiments, one or more computer systems <NUM> perform one or more steps of one or more methods described or illustrated herein. In particular embodiments, one or more computer systems <NUM> provide functionality described or illustrated herein. In particular embodiments, software running on one or more computer systems <NUM> performs one or more steps of one or more methods described or illustrated herein or provides functionality described or illustrated herein. Particular embodiments include one or more portions of one or more computer systems <NUM>. Herein, reference to a computer system may encompass a computing device, and vice versa, where appropriate. Moreover, reference to a computer system may encompass one or more computer systems, where appropriate.

In particular embodiments, processor <NUM> includes hardware for executing instructions, such as those making up a computer program. As an example and not by way of limitation, to execute instructions, processor <NUM> may retrieve (or fetch) the instructions from an internal register, an internal cache, memory <NUM>, or storage <NUM>; decode and execute them; and then write one or more results to an internal register, an internal cache, memory <NUM>, or storage <NUM>. In particular embodiments, processor <NUM> may include one or more internal caches for data, instructions, or addresses. This disclosure contemplates processor <NUM> including any suitable number of any suitable internal caches, where appropriate. As an example and not by way of limitation, processor <NUM> may include one or more instruction caches, one or more data caches, and one or more translation lookaside buffers (TLBs). Instructions in the instruction caches may be copies of instructions in memory <NUM> or storage <NUM>, and the instruction caches may speed up retrieval of those instructions by processor <NUM>. Data in the data caches may be copies of data in memory <NUM> or storage <NUM> for instructions executing at processor <NUM> to operate on; the results of previous instructions executed at processor <NUM> for access by subsequent instructions executing at processor <NUM> or for writing to memory <NUM> or storage <NUM>; or other suitable data. The data caches may speed up read or write operations by processor <NUM>. The TLBs may speed up virtual-address translation for processor <NUM>. In particular embodiments, processor <NUM> may include one or more internal registers for data, instructions, or addresses. This disclosure contemplates processor <NUM> including any suitable number of any suitable internal registers, where appropriate. Where appropriate, processor <NUM> may include one or more arithmetic logic units (ALUs); be a multi-core processor; or include one or more processors <NUM>. Although this disclosure describes and illustrates a particular processor, this disclosure contemplates any suitable processor.

In particular embodiments, memory <NUM> includes main memory for storing instructions for processor <NUM> to execute or data for processor <NUM> to operate on. As an example and not by way of limitation, computer system <NUM> may load instructions from storage <NUM> or another source (such as, for example, another computer system <NUM>) to memory <NUM>. Processor <NUM> may then load the instructions from memory <NUM> to an internal register or internal cache. To execute the instructions, processor <NUM> may retrieve the instructions from the internal register or internal cache and decode them. During or after execution of the instructions, processor <NUM> may write one or more results (which may be intermediate or final results) to the internal register or internal cache. Processor <NUM> may then write one or more of those results to memory <NUM>. In particular embodiments, processor <NUM> executes only instructions in one or more internal registers or internal caches or in memory <NUM> (as opposed to storage <NUM> or elsewhere) and operates only on data in one or more internal registers or internal caches or in memory <NUM> (as opposed to storage <NUM> or elsewhere). One or more memory buses (which may each include an address bus and a data bus) may couple processor <NUM> to memory <NUM>. Bus <NUM> may include one or more memory buses, as described below. In particular embodiments, one or more memory management units (MMUs) reside between processor <NUM> and memory <NUM> and facilitate accesses to memory <NUM> requested by processor <NUM>. In particular embodiments, memory <NUM> includes random access memory (RAM). This RAM may be volatile memory, where appropriate. Where appropriate, this RAM may be dynamic RAM (DRAM) or static RAM (SRAM). Moreover, where appropriate, this RAM may be single-ported or multi-ported RAM. This disclosure contemplates any suitable RAM. Memory <NUM> may include one or more memories <NUM>, where appropriate. Although this disclosure describes and illustrates particular memory, this disclosure contemplates any suitable memory.

In particular embodiments, communication interface <NUM> includes hardware, software, or both providing one or more interfaces for communication (such as, for example, packet-based communication) between computer system <NUM> and one or more other computer systems <NUM> or one or more networks. As an example and not by way of limitation, communication interface <NUM> may include a network interface controller (NIC) or network adapter for communicating with an Ethernet or other wire-based network or a wireless NIC (WNIC) or wireless adapter for communicating with a wireless network, such as a WI-FI network. This disclosure contemplates any suitable network and any suitable communication interface <NUM> for it. As an example and not by way of limitation, computer system <NUM> may communicate with an ad hoc network, a personal area network (PAN), a local area network (LAN), a wide area network (WAN), a metropolitan area network (MAN), or one or more portions of the Internet or a combination of two or more of these. One or more portions of one or more of these networks may be wired or wireless. As an example, computer system <NUM> may communicate with a wireless PAN (WPAN) (such as, for example, a BLUETOOTH WPAN), a WI-FI network, a WI-MAX network, a cellular telephone network (such as, for example, a Global System for Mobile Communications (GSM) network, a Long-Term Evolution (LTE) network, or a <NUM> network), or other suitable wireless network or a combination of two or more of these. Computer system <NUM> may include any suitable communication interface <NUM> for any of these networks, where appropriate. Communication interface <NUM> may include one or more communication interfaces <NUM>, where appropriate. Although this disclosure describes and illustrates a particular communication interface, this disclosure contemplates any suitable communication interface.

In summary, in one embodiment, a method is implemented by an apparatus of a segment routing (SR) network including receiving a data packet and accessing an attestation token for the apparatus. The method further includes determining a location within a header of the received data packet for the attestation token and creating an updated header by encoding the attestation token in the determined location of the header. The method further includes sending the updated header with the encoded attestation token to another apparatus of the SR network.

Embodiments described herein include various elements and limitations, with no one element or limitation contemplated as being a critical element or limitation. Each of the claims individually recites an aspect of the embodiment in its entirety. Moreover, some embodiments described may include, but are not limited to, inter alia, systems, networks, integrated circuit chips, embedded processors, ASICs, methods, and computer-readable media containing instructions. One or multiple systems, devices, components, etc., may comprise one or more embodiments, which may include some elements or limitations of a claim being performed by the same or different systems, devices, components, etc. A processing element may be a general processor, task-specific processor, a core of one or more processors, or other co-located, resource-sharing implementation for performing the corresponding processing. The embodiments described hereinafter embody various aspects and configurations, with the figures illustrating exemplary and non-limiting configurations. Computer-readable media and means for performing methods and processing block operations (e.g., a processor and memory or other apparatus configured to perform such operations) are disclosed and are in keeping with the extensible scope of the embodiments. The term "apparatus" is used consistently herein with its common definition of an appliance or device.

The steps, connections, and processing of signals and information illustrated in the figures, including, but not limited to, any block and flow diagrams and message sequence charts, may typically be performed in the same or in a different serial or parallel ordering and/or by different components and/or processes, threads, etc., and/or over different connections and be combined with other functions in other embodiments, unless this disables the embodiment or a sequence is explicitly or implicitly required (e.g., for a sequence of read the value, process said read value - the value must be obtained prior to processing it, although some of the associated processing may be performed prior to, concurrently with, and/or after the read operation). Also, nothing described or referenced in this document is admitted as prior art to this application unless explicitly so stated.

The term "one embodiment" is used herein to reference a particular embodiment, wherein each reference to "one embodiment" may refer to a different embodiment, and the use of the term repeatedly herein in describing associated features, elements and/or limitations does not establish a cumulative set of associated features, elements and/or limitations that each and every embodiment must include, although an embodiment typically may include all these features, elements and/or limitations. In addition, the terms "first," "second," etc., as well as "particular" and "specific" are typically used herein to denote different units (e.g., a first widget or operation, a second widget or operation, a particular widget or operation, a specific widget or operation). The use of these terms herein does not necessarily connote an ordering such as one unit, operation or event occurring or coming before another or another characterization, but rather provides a mechanism to distinguish between elements units. Moreover, the phrases "based on x" and "in response to x" are used to indicate a minimum set of items "x" from which something is derived or caused, wherein "x" is extensible and does not necessarily describe a complete list of items on which the operation is performed, etc. Additionally, the phrase "coupled to" is used to indicate some level of direct or indirect connection between two elements or devices, with the coupling device or devices modifying or not modifying the coupled signal or communicated information. Moreover, the term "or" is used herein to identify a selection of one or more, including all, of the conjunctive items. Additionally, the transitional term "comprising," which is synonymous with "including," "containing," or "characterized by," is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. Finally, the term "particular machine," when recited in a method claim for performing steps, refers to a particular machine within the <NUM> USC § <NUM> machine statutory class.

Claim 1:
An apparatus of a segment routing, SR, network, the apparatus comprising:
one or more processors; and
one or more computer-readable storage media coupled to the one or more processors and comprising instructions operable when executed by the one or more processors to cause the one or more processors to perform operations comprising:
receiving (<NUM>) a data packet;
accessing (<NUM>) an attestation token that provides verifiable evidence of trustworthiness of the apparatus and/or that allows validation, by another apparatus of the SR network, of freshness of data asserted by the apparatus based on the state of internal counters within a Trusted Platform Module comprised in the apparatus;
determining (<NUM>) a location within a header of the received data packet for the attestation token;
creating (<NUM>) an updated header by encoding the attestation token in the determined location of the header, wherein encoding the attestation token in the determined location of the header comprises writing the attestation token in a Type-Length-Value, TLV; and
sending (<NUM>) the data packet with the updated header with the encoded attestation token to another apparatus of the SR network.