EP0197392A2
Expired / Lapsed
EP
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Improvements in cryptographic communication
Assignee: International Business Machines Corp
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Filing: 1986-03-21
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Granted: —
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Expires: 2006-03-21
Abstract
Abstract A method for authenticating nodes/users and in protecting .data flow between nodes. This is facilitated by creating a dialogue involving authenticated encryption among the nodes. During each session, a key for use in cryptographic conversion is constructed among the node participants in order to permit symmetric authentication. The key is unique to the session. A different key is generated for each and every session. The building of the session key involves sharing of a minimal amount of information among the participants in the form of combining both a random number and authentication indicia.
Inventors
- 👤 Walter Ernst Bass
- 👤 Stephen Michael Matyas
- 👤 Jonathan Oseas (Nmn)
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 08:38
CPC Classifications
H; H04; H04L; H04L9/00; H04L9/002; H04L9/06; H04L9/0618; H04L9/0625; H04L9/0637; H04L9/08; H04L9/0816; H04L9/0838; H04L9/0841; H04L9/0844; H04L9/0861; H04L9/0869
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
153 words
A method for establishing a session key for use for communication between remote locations and and for authenticating the node/user identities, said key being valid only for the duration of a single cryptographic session, each node of the pair hav- 40 ing a local cryptographic facility including a pre-established cross-domain key and an attribute associated with the other node/user identity, comprising the steps at each node of: (a) generating a random number, encrypting 45 said random number under the cross-domain . key, copying said encrypted number to the other node, and decrypting under the cross-domain key any received encrypted random number from said other node; 50 (b) forming a parameter by combining the attributes derived or associated with the identities of both nodes/users; (c) forming an interim key from the composite of the local and received random numbers; 55 and (d) combining the parameter with the interim key to produce the session key.
Claim 2
Independent Claim
153 words
A method for establishing a session key for use for communication between remote locations and and for authenticating the node/user identities, said key being valid only for the duration of a single cryptographic session, each node of the pair hav- 40 ing a local cryptographic facility including a pre-established cross-domain key and an attribute associated with the other node/user identity, comprising the steps at each node of: (a) generating a random number, encrypting 45 said random number under the cross-domain . key, copying said encrypted number to the other node, and decrypting under the cross-domain key any received encrypted random number from said other node; 50 (b) forming a parameter by combining the attributes derived or associated with the identities of both nodes/users; (c) forming an interim key from the composite of the local and received random numbers; 55 and (d) combining the parameter with the interim key to produce the session key.
Claim 3
Dependent Claim
21 words
A method according to claim 1, wherein the cross-domain key includes a local and remote variant, all unidirectional keys being dissimilar.
Claim 4
Dependent Claim
29 words
A method according to claim 1 or claim 2, wherein the attribute associated with each node/user identity is selectively obtained by either table lookup or by way of computation.
Claim 5
Dependent Claim
45 words
A method according to claim 2, wherein the cryptographic facility of each node further includes no more than the local and remote variants of each of a plurality of distinguishable cross-domain keys corresponding to the number of nodes with which it can potentially cryptographically communicate.
Claim 6
Independent Claim
38 words
A method as claimed in any one of claims 1-4, wherein the step of combining the parameter with the interim key to produce the session key includes the step of encrypting the parameter with the interim key. -
Claim 7
Independent Claim
187 words
A method for establishing a key commutatively among n cryptographically _communicating nodes _ and for authenticating node/user identities, said key being valid only for the duration of a single cryptographic session, each of the nodes having a local cryptographic facility including a plurality of pre-established cross-domain keys, and a concordance between a plurality of node/user identities and at least one attribute associated therewith, comprising the steps at each node of: (a) copying its node/user identity to the (n-1) other nodes and responsively obtaining the identity of said (n-1) other nodes; (b) generating a random number, encrypting it under each of the pre-established cross-domain keys, copying each one of the set of encrypted numbers to each one of the set of counterpart (n-1) other nodes, and decrypting under the counterpart cross-domain keys the received encrypted random numbers from the counterpart nodes; (c) forming a parameter by combining the attributes derived or associated with the identities of the n nodes/users; (d) forming an interim key from the composite of the local and received random numbers; and (e) combining the parameter with the interim key to produce the session key.
Claim 8
Independent Claim
187 words
A method for establishing a key commutatively among n cryptographically _communicating nodes _ and for authenticating node/user identities, said key being valid only for the duration of a single cryptographic session, each of the nodes having a local cryptographic facility including a plurality of pre-established cross-domain keys, and a concordance between a plurality of node/user identities and at least one attribute associated therewith, comprising the steps at each node of: (a) copying its node/user identity to the (n-1) other nodes and responsively obtaining the identity of said (n-1) other nodes; (b) generating a random number, encrypting it under each of the pre-established cross-domain keys, copying each one of the set of encrypted numbers to each one of the set of counterpart (n-1) other nodes, and decrypting under the counterpart cross-domain keys the received encrypted random numbers from the counterpart nodes; (c) forming a parameter by combining the attributes derived or associated with the identities of the n nodes/users; (d) forming an interim key from the composite of the local and received random numbers; and (e) combining the parameter with the interim key to produce the session key.
Claim 9
Dependent Claim
17 words
A method according to claim 6, wherein each cross-domain key includes a local and remote variant thereof.
Claim 10
Dependent Claim
41 words
A method according to claim 6, wherein generated random numbers are encrypted under the local variant corresponding to each cross-domain key while any received encrypted random numbers from counterpart nodes are decrypted under the remote variant of the counterpart cross-domain key.
Claim 11
Dependent Claim
25 words
A method according to claim 6, wherein the local and received random numbers which form an interim key are encrypted under the counterpart remote variant.
Claim 12
Dependent Claim
33 words
A method according to claim 6, wherein the step of combinining the parameter with the interim key to produce the session key includes the step of encrypting the parameter with the interim key.
Claim 13
Dependent Claim
64 words
A method according to claim 1 or 6, wherein the step of the interim key forming includes the exclusive OR'ing of the local and received random number; and wherein the step of encrypting the parameter with the interim key to produce the session key includes the step of additively combining the attributes corresponding to the counterpart node/user identities, and then encrypting the additive combination.
Claim 14
Dependent Claim
32 words
A method according to claim 1 or 6, wherein the steps of combining the attributes to form a parameter or forming a composite of local and received random numbers are commutative step.
Claim 15
Dependent Claim
24 words
A method according to claim 1 or 6, wherein each attribute is a value ascertained as a one-way function of node/user identity or indicia.
Claim 16
Dependent Claim
35 words
A method acccording to claim 1 or 6, wherein there is provided the additional step of checking to verify that the session key so generated is the same at both the sending and receiving nodes.
References Cited (Backward Citations)
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