Microsoft Technology Licensing, LLC

Hitachi, Ltd.

Michael Roe

Tuomas Aura

Gregory O'Shea

Hiroshi Yoshiura

David G Thaler

Brian Don Zill

Art Shelest

Hajime Morito

Steven Murdoch

Soichi Furuya

Secure network location awareness is provided whereby a client is able to use appropriate settings when communicating with an access node of a communications network. In an embodiment a client receives a signed message from the access node, the signed message comprising at least a certificate chain having a public key. In some embodiments the certificate chain may be only a self-signed certificate and in other embodiments the certificate chain is two or more certificates in length. The client validates the certificate chain and verifies the signature of the signed message. If this is successful the client accesses stored settings for use with the access node. The stored settings are accessed at least using information about the public key. In another embodiment the signed message also comprises a location identifier which is, for example, a domain name system (DNS) suffix of the access node.

Secure network location awareness

Disclosed is an authentication mechanism that enables an information recipient to ascertain that the information comes from the sender it purports to be from. This mechanism integrates a private/public key pair with selection by the sender of a portion of its address. The sender derives its address from its public key, for example, by using a hash of the key. The recipient verifies the association between the address and the sender's private key. The recipient may retrieve the key from an insecure resource and know that it has the correct key because only that key can produce the sender's address in the message. The hash may be made larger than the sender-selectable portion of the address. The recipient may cache public key/address pairs and use the cache to detect brute force attacks and to survive denial of service attacks. The mechanism may be used to optimize security negotiation algorithms.

Methods and systems for unilateral authentication of messages

To allow down-level devices to participate in a network controlled by a protocol including CGAS or ECGAs, the CGA or ECGA authentication may be made optional to allow the down-level devices to execute non-CGA or non-ECGA versions of network protocols, while at the same time allowing the use of CGA- and/or ECGA-authenticated versions of the same protocols. To identify non-cryptographic addresses (e.g., non-CGA and non-ECGA), the address bits of a non-CGA or non-ECGA such that the address cannot be or is probably not an encoding of the hash of a public key. In this manner, a receiving node may properly identify the capabilities of the sending node, perform an appropriate authentication of the message containing the non-cryptographic address, and/or prioritize processing of information contained in the message with the non-cryptographic address.

Non-cryptographic addressing

Dynamic host configuration protocol (DHCP) is extended in order to assist with secure network location awareness. In an embodiment a DHCP client receives a signed DHCP response message from a DHCP server, the signed message comprising at least a certificate chain having a public key. In that embodiment the DHCP client validates the certificate chain and verifies the signature of the signed message. If this is successful the DHCP client accesses stored settings for use with the server. The stored settings are accessed at least using information about the public key. In some embodiments signed DHCPOFFER messages and signed DHCPACK messages are used. In another embodiment the signed DHCP message comprises a location identifier which is, for example, a domain name system (DNS) suffix of a DHCP server.

Dynamic host configuration protocol

An extensible cryptographically generated network address may be generated by forming at least a portion of the network address as a portion of a first hash value. The first hash value may be formed by generating a plurality of hash values by hashing a concatenation of a public key and a modifier using a second hash function until a stop condition. The stop condition may include computing the plurality of hash values for a period of time specified by a time parameter. A second hash value may be selected from the plurality of hash values, and the modifier used to compute that hash value may be stored. A hash indicator may be generated which indicates the selected second hash value. The first hash value may be generated as a hash of a concatenation of at least the public key and the modifier. At least a portion of the node-selectable portion of the network address may include at least a portion of the first hash value.

Using time to determine a hash extension

The hash extension technique used to generate an ECGA may be used to increase the strength of one-way hash functions and/or decrease the number of bits in any situation where some external requirement limits the number of hash bits, and that limit is below what is (or may be in the future) considered secure against brute-force attacks. For example, to decrease the length of human entered security codes (and maintain the same security), and/or to increase the strength of a human entered security code (and maintain the length of the security code), the security code may be generated and/or authenticated using an extended hash method.

Human input security codes

A system and method for authentication verifies the address of an information sender based on the sender's address, public key, and a digital signature. A portion of the sender's address is derived from the public key, such as by incorporating a portion of a hash of the public key with or without a modifier. The sender provides information including content data, the public key, the address, and the digital signature generated using the private key corresponding to the public key. Upon reception, the recipient verifies the address by recreating it from the public key. The signature is verified using the network address and public key. The recipient accepts the content data when both the address and signature are verified. The content data may include a communications parameter of the sender, such as a care-of address where the sender is a mobile device and the recipient is the sender's home agent.

An encryption system comprises a pseudo-random number generator (KS) for generating a long pseudo-random sequence (S) from a shorter encryption key (K) and, if necessary, a nonce value (N), and a mixing function (MX) for combining the sequence with a plaintext message (P) on a block-by-block basis, where successive blocks (S(i)) of 128 bits of the sequence are combined with successive 64-bit blocks of plaintext (P(i)) to produce successive 64-bit blocks of ciphertext. The blockwise use of a long pseudo-random sequence preserves the advantages of a block cipher in terms of data confidentiality and data integrity, as well as benefiting from the speed advantages of a stream cipher.

Cryptographic apparatus and method

An apparatus and method of copy protection for use in digital data recorders such as DVD-RAM recorders, which includes embedding transmission time information into a digital data stream by digital watermarking and comparing the transmission time with the current time at the data recorder (). If the time difference is less than a threshold value it is presumed that the recording is for time-shifting purposes, namely recording a programme to watch later, which is generally allowed by copyright laws. If the time difference is greater than a threshold value it is presumed that the recording is an attempted unauthorized recording such as from a pre-recorded copy, and further recording is prevented.

Copy protection apparatus and method

An apparatus and method of copy protection for use in digital data recorders such as DVD-RAM recorders, which includes embedding transmission time information into a digital data stream by digital watermarking and comparing the transmission time with the current time at the data recorder (,). If the time difference is less than a threshold value it is presumed that the recording is for time-shifting purposes, namely recording a programme to watch later, which is generally allowed by copyright laws. If the time difference is greater than a threshold value it is presumed that the recording is an attempted unauthorised recording such as from a pre-recorded copy, and further recording is prevented.

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Cambridge, United Kingdom

Michael Roe