Abstract: Some embodiments provide a system to generate a key pair. During operation, the system can receive a request to generate the key pair, wherein the key pair is generated by a key assigner, and wherein the key pair is associated with a user. Next, the system can determine a secret associated with the key assigner. Specifically, the system can determine the secret by determining an initial secret associated with the key assigner, and by applying a one-way hash function to the initial secret one or more times. The system can then determine a seed based on the secret. Specifically, the system can determine the seed by cryptographically combining the secret with information associated with the user. Next, the system can generate the key pair by using the seed as an input to a key generator. The system can then return the key pair to a requestor.

Abstract: One embodiment of the present invention provides a system that maintains keys using limited storage space on a computing device, such as a smart card. During operation, the system receives a request at the computing device to perform an operation involving a key. While processing the request, the system obtains an encrypted key from remote storage located outside of the computing device, wherein the encrypted key was created by encrypting the key along with an expiration time for the key. Next, the system decrypts the encrypted key to restore the key and the expiration time, wherein the encrypted key is decrypted using a computing-device key, which is maintained locally on the computing device. Finally, if the expiration time has not passed, the system uses the key to perform the requested operation. Note that by storing the encrypted key in remote storage, the computing device is able to use the key without consuming local storage space to store the key.

Abstract: Some embodiments of the present invention provide a system that generates and retrieves a key derived from a master key. During operation, the system receives a request at a key manager to generate a new key, or to retrieve an existing key. To generate a new key, the system generates a key identifier and then derives the new key by cryptographically combining the generated key identifier with the master key. To retrieve an existing key, the system obtains a key identifier for the existing key from the request and then cryptographically combines the obtained key identifier with the master key to produce the existing key.

Abstract: Some embodiments of the present invention provide a system that computes a target secret St in a sequence of secrets S0 . . . Sn. During operation, the system obtains k hash functions h1, . . . , hk, where h1 is known as the “lowest order hash function”, and hk is known as the “highest order hash function.” Associated with each hash function hi is a seed value seed comprising a pair (seedindexi, seedvaluei). Hash function hi operates on a pair (indexi, valuei) to produce a pair (newindexi, newvaluei), where newindexi>indexi. To compute target secret St, the hash functions are applied successively, starting with the highest order hash function whose associated seed's index value is largest without being greater than t, applying that hash function as many times as possible without having that hash function's output's index value become greater than t, and then applying each successive hash function in turn as many times as possible, until St has been computed.

Abstract: One embodiment of the present invention provides a system that facilitates making the files permanently unreadable. During operation, the system encrypts a file with a key K at a file manager and then stores the encrypted file in non-volatile storage. Next, the system stores the key K in a key database located in volatile storage at the file manager. The system then encrypts the key database, and stores the encrypted key database in non-volatile storage. Additionally, a key that can be used to decrypt the encrypted key database is maintained by a key manager, and is not maintained in non-volatile form by the file manager. In this way, if the file manager crashes, losing the contents of its volatile storage, the file manager must interact with the key manager to decrypt the encrypted key database.

Abstract: Some embodiments of the present invention provide a system that automatically revokes data on a portable computing device. During operation, the system uses a key K1 to encrypt data on the portable computing device. The system then attempts verify that the portable computing device is secure. If the attempt to verify that the portable computing device is secure fails, the system causes K1 to be removed from the portable computing device.

Abstract: A method and system is disclosed for utilizing an ephemeral encryption or decryption agent so as to preclude access by the ephemeral encryption agent or decryption agent, respectively, to the information being ephemerally encrypted or decrypted. To preclude access by the ephemeral encryption agent, a blinding function is applied to the information prior to forwarding such information to the encryption agent for encryption. To preclude access to the information by the ephemeral decryption agent, a blinding function is applied to the encrypted information prior to forwarding the encrypted information to the decryption agent for decryption. Once the information has been returned, the information is unblinded, leaving an encrypted or decrypted message respectively.

Abstract: One embodiment of the present invention provides a system that transparently interconnects multiple network links into a single virtual network link. During operation, a Rbridge (Rbridge) within the system receives a packet, wherein the Rbridge belongs to a set of one or more Rbridges that transparently interconnect the multiple network links into the single virtual network link. These Rbridges automatically obtain information specifying which endnodes are located on the multiple network links without the endnodes having to proactively announce their presence to the Rbridges. If a destination for the packet resides on the same virtual network link, the Rbridge routes the packet to the destination. This route can be an optimal path to the destination, and is not constrained to lie along a spanning tree through the set of Rbridges.

Abstract: One embodiment of the present invention provides a system for operating a key distribution center (KDC) that provides keys to facilitate secure communications between clients and servers across a computer network, wherein the system operates without having to store long-term server secrets. The system operates by receiving a communication from a server at the KDC. This communication includes an identifier for the server, as well as a temporary secret key to be used in communications between a client and the server for a limited time period. In response the communication, the system attempts to authenticate the server. If the server is successfully authenticated, the system stores the temporary secret key at the KDC, so that the temporary secret key can be subsequently used to facilitate communications with the server.

Abstract: One embodiment of the present invention provides a system for accessing an encrypted file through a file system. During operation, the system receives a request to access the encrypted file. In response to the request, the system sends an encrypted file key for the encrypted file from the file system to a tamper-resistant module. Next, the tamper-resistant module uses a master secret to decrypt the encrypted file key to restore the file key, wherein the master secret is obtained from an external source by the tamper-resistant module. The system then uses the file key to access the encrypted file.

Abstract: A method and system for utilizing and encryption or decryption agent so as to preclude access by the encryption agent or decryption agent, respectively, to the information being encrypted or decrypted. To preclude access by the encryption agent, a blinding function is applied to the information prior to forwarding such information to the encryption agent for encryption. To preclude access to the information by the decryption agent, a blinding function is applied to the encrypted information prior to forwarding the encrypted information to the decryption agent for decryption. Once the information has been returned, the information is unblinded, leaving an encrypted or decrypted message respectively.

Abstract: One embodiment of the present invention provides a system that prevents loops from occurring when spanning tree configuration messages are lost while executing a spanning tree protocol on bridges in a network. During operation, the system executes the spanning tree protocol on a bridge. This spanning tree protocol configures each port coupled to the bridge into either a forwarding state, in which messages are forwarded to and from the port, or a backup state, in which messages are not forwarded to or from the port. The system also monitors ports coupled to the bridge to determine when messages are lost by the ports. If one or more messages are lost on a port, the system refrains from forwarding messages to or from the port until no messages are lost by the port for an amount of time.

Abstract: In accordance with the invention, a presenter of credentials presents to a recipient of credentials one or more chains of group credentials to prove entity membership or non-membership in a nested group in a computer network. The ability to present a chain of credentials is particularly important when a client is attempting the prove membership or non-membership in a nested group and one or more of the group servers in the family tree are off-line. A chain of group credentials includes two or more proofs of group membership and/or proofs of group non-membership Furthermore, the proofs of group membership may include one or more group membership certificates and/or one or more group membership lists; and proofs of group non-membership may include one or more group non-membership certificates and/or one or more group membership lists.

Abstract: A method and apparatus for utilizing a non-secure file server for storing and sharing data securely only among clients and groups authorized to read and modify the data. A first client that desires to store data on the file server encrypts the data with a first encryption key having an associated first decryption key. The client encrypts the first decryption key with a second encryption key having an associated second decryption key known to the first client. Additionally, the first decryption key is encrypted with respective encryption keys of other clients or groups intended to have access to the data stored on the file server and the clients and groups retain their respective decryption keys. All of the encrypted first decryption keys are stored within an access control list in association with the encrypted data on the non-secure file server.

Abstract: A system and method for adding routing information for a node to a routing table, which efficiently makes necessary changes to the routing table to support routing to and from the node, while maintaining the deadlock-free quality of the paths described by the routing table. The routing table is generated by storing routing information in the routing table that reflects and describes a deadlock-free set of paths through a network of nodes. A row of entries is added to the routing table describing how to forward data units from the node. A column of entries is added to the routing table describing how to forward data units addressed to the node. The forwarding information within each entry added to the routing table maintains the deadlock-free quality of the set of paths represented by the forwarding table.

Abstract: A distributed system and method generate “layered routes” that reflect a layered representation of a network, which representation provides deadlock-free routes. The layered representation consists of an ordered set of layers, where each layer is a deadlock-free sub-topology of the network. In determining routes, the links used in each route are constrained to be taken from layers of non-decreasing order as the route extends from source to destination. A device that determines a better or equal cost path to a destination node with respect to its current path to that node sends a route information message to its neighbor devices. The receiver of a route information message may then accept the message and begin using the new path described by the message, or reject the message without using the new path.

Abstract: A method and system for evaluating a set of credentials that includes at least one group credential and that may include one or more additional credentials. A trust rating is provided in association with the at least one group credential within the set of credentials and trust ratings may also be provided in other credentials within the set of credentials. Each trust rating provides an indication of the level of confidence in the information being certified in the respective credential. In response to a request for access to a resource or service, an evaluation of the group credentials is performed by an access control program to determine whether access to the requested resource or service should be provided. In one embodiment, within any given certification path a composite trust rating for the respective path is determined. An overall trust rating for the set of credentials is determined based upon the composite trust ratings.

Abstract: One embodiment of the present invention provides a system that facilitates instant failover during packet routing by employing a flooding protocol to send packets between a source and a destination. Upon receiving a packet containing data at an intermediate node located between the source and the destination, the system determines whether the packet has been seen before at the intermediate node. If not, the system forwards the packet to neighboring nodes of the intermediate node. In one embodiment of the present invention, forwarding the packet to neighboring needs involves forwarding the packet to all neighboring nodes except the node from which the packet was received. In one embodiment of the present invention, determining whether the packet has been seen before involves examining a sequence number, SR, contained within the packet to determine whether the sequence number has been seen before.

Abstract: One embodiment of the present invention provides a system that replaces an attachment to an email message with a reference to a location where the attachment is stored. Upon receiving the email message, the system examines the email message to determine if the email message includes an attachment. If the email message includes the attachment, the system stores the attachment at a location on a communication network from which the attachment can be retrieved. The system also modifies the email message by replacing the attachment with a reference specifying the location of the attachment, and sends the modified email message to a recipient of the email message. In one embodiment of the present invention, the recipient receives the modified email message and uses the reference specifying the location of the attachment to retrieve the attachment across the communication network.

Abstract: A method and apparatus for securely communicating ephemeral information from a first node to a second node. In a first embodiment, the first node encodes and transmits an ephemeral message encrypted at least in part with an ephemeral key, from the first node to the second node. Only the second node has available to it the information that is needed to achieve decryption by an ephemeral key server of a decryption key that is needed to decrypt certain encrypted payload information contained within the message communicated from the first node to the second node. In a second embodiment the first node transmits to the second node an ephemeral message that is encrypted at least in part with an ephemeral key. The ephemeral message includes enough information to permit the second node to communicate at least a portion of the message to an ephemeral key server and for the ephemeral key server to verify that the second node is an authorized decryption agent for the message.