Cryptography – Key management – Key distribution
Reexamination Certificate
1998-10-28
2002-03-26
Decady, Albert (Department: 2131)
Cryptography
Key management
Key distribution
Reexamination Certificate
active
06363154
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to systems, methods and computer program products for communicating among nodes that are connected to a communications network, and more particularly to systems, methods and computer program products for sending and receiving secure messages among nodes that are connected to a communications network.
BACKGROUND OF THE INVENTION
Communications networks are widely used to send and receive messages among nodes that are connected thereto. Communications networks may include wired and wireless communications networks, local area networks, the Internet, buses that connect two or more nodes, and combinations thereof. Nodes may include mainframe, mid-range and personal computers, workstations, radiotelephones, application programs such as client and server programs, devices such as smart cards and cryptographic adapters, and combinations thereof. In network communications, data may be encrypted selectively, ancrypted may stay end until it is decrypted by the intended recipient or recipients.
Encryption often occurs between two communicating nodes: a single sender and a single receiver. However, there are situations where messages are communicated to multiple other nodes, or data is shared with multiple other nodes. For example, a user may wish to send an encrypted email message to several other users, whose email addresses are contained in a distribution list. Alternatively, a user may wish to send an encrypted document, attached to an email message, to several other users.
Existing key derivation and key transport protocols, which may work well between two communicating nodes, may not work as well when there are multiple recipients. For example, the sender of an email message can separately encrypt the data key that is used to encrypt the data, in the public key of each recipient. However, if users in this closed group will have a subsequent need to communicate or share additional encrypted messages or documents with other users of the same group, the above-described method of encrypting the data-encrypting keys in the public key of each recipient may not be an efficient or effective solution, because the method may not scale well.
Other conventional mechanisms for generating and distributing group symmetric keys may rely on a Key Distribution Center (KDC) to manage the setup of symmetric keys. A group key request may be sent to the KDC. The KDC then contacts each group member and distributes the symmetric key. The group members can then secure group communication.
For example, A. Ballardie, “
Scalable Multicast Key Distribution
”, IETF RFC-1949, May 1996, defines a multicast key distribution method using a “core based tree” multicast scheme. In a group of communicating users, a delivery multicast tree is built around several core members. One of the core members is assigned the role of primary core and the group key distribution center. Once the core based tree is established, the primary core member (i.e., the group key distribution center) creates a group key, encrypts it with each core public key and sends it to the core members. After receiving the group key, each core member then encrypts the group key with the public keys of its subordinates and sends it to them. When a group member wants to send an encrypted message to other members, it sends a request to the primary core. The primary core creates a session key (i.e., a data encrypting key), encrypts it with the group key, and sends it to secondary cores for distribution to group members over the core based tree.
Similarly, Harney et al., “
Group Key Management Protocol
(
GKMP
)
Specification
”, IETF RFC-2093, July 1997, and “
Group Key Management Protocol
(
GKMP
)
Architecture
”, IETF RFC-2094, July 1997, define a group key management protocol to create group symmetric keys and distribute them among group members. A “group controller” creates a “group traffic encrypting key”, encrypts it with each member's public key, and sends it to the group members. Then, the group controller contacts each member of the group and creates a “session traffic encrypting key” for that member. When a group member wants to send an encrypted message to other members, it encrypts the message using its session traffic encrypting key.
Finally, ANSI X9.69
, “Key Management Extensions
”, 1998, defines a role-based key management scheme for distribution of symmetric keys. A policy manager defines one or more “domains” with each being specified by a “Domain Authority” (DA). Three symmetric keys are used to generate “working keys”. These are “Domain Key Split”, “Maintenance Key Split”, and “Random Key Split”. A DA generates two symmetric keys: a Domain Key Split and a Maintenance Key Split. The DA sends these two keys to all the users in its domain. The Maintenance Key Split is used to update the Domain Key Split. To encrypt a message a “Working Key” is derived from the three symmetric keys. The message is encrypted with the Working Key.
Notwithstanding the above-described mechanisms for generating and distributing group symmetric keys, there continues to be a need for systems, methods and computer program products for sending secure message among a group of nodes selected from a plurality of nodes that are connected to a communications network.
SUMMARY OF THE INVENTION
The present invention provides systems, methods and/or computer program products for sending secure messages among a group of nodes selected from a plurality of nodes that are connected to a communications network, by defining a group key at any one of the group of nodes. The group key is then sent to remaining ones of the group of nodes. A message is encrypted at any one of the group of nodes using a session key that is generated from the group key. The encrypted message is sent to remaining ones of the group of nodes.
Accordingly, scaleable systems, methods and/or computer program products can create and distribute symmetric keys among a group of communicating nodes. Unlike conventional group key management mechanisms, the present invention need not use a centralized key distribution center—only the group members may generate and distribute group symmetric keys. The group symmetric keys permit each node to conveniently and securely communicate, share, and access data belonging to the group. A group of communicating nodes can thus send secure messages to the group members without having to send the session key individually to each node.
More specifically, systems, methods and/or computer program products for sending secure messages among a group of nodes selected from a plurality of nodes that are connected to a communications network, define a random secret key at a first one of the group of nodes. The random secret key is sent from the first one of the group nodes to remaining ones of the group of nodes. A random number is generated at a second one of the group of nodes. A one-way hash of the random number and the random secret key is performed at the second one of the group of nodes to generate a working key. A message is encrypted at the second one of the group of nodes, using the working key. The encrypted message and the random number is sent from the second one of the group of nodes to remaining ones of the group of nodes.
The encrypted message and the random number are received at the remaining ones of the group of nodes. Each of the remaining ones of the group of nodes performs a one-way hash of the random number and the random secret key, to regenerate the working key. The message is then decrypted using the regenerated working key. It will be understood that the secret key may be defined at any one of the group of nodes rather than a predefined, centralized key distribution center. Moreover, the random number may be generated at any one of the group of nodes that desires to communicate an encrypted message to remaining ones of the group of nodes. Decentralized group key management is thereby provided.
Key transport may also be performed by generating a data encrypting key at the second one of the group of nodes and encry
Matyas, Jr. Stephen Michael
Peyravian Mohammad
Zunic Nevenko
De'cady Albert
International Business Machines - Corporation
Myers Bigel Sibley & Sajovec P.A.
Ray-Yarletts Jeanine S.
Smithers Matthew
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