Browse Prior Art Database

Clock Protected Cryptography

IP.com Disclosure Number: IPCOM000048409D
Original Publication Date: 1982-Jan-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 2 page(s) / 14K

Publishing Venue

IBM

Related People

Fennel, JW: AUTHOR [+2]

Abstract

An earth station must be able to power up from a cold start and join in existing operating network. The new station must synchronize with the network and must deduce the appropriate initialization vector to start its cryptographic operation. Since the initialization vector is derived from the synchronization information, the earth station can be fooled by false synchronizing information into generating past or future random streams and thus be manipulated as a captive earth station into performing decipherment.

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Clock Protected Cryptography

An earth station must be able to power up from a cold start and join in existing operating network. The new station must synchronize with the network and must deduce the appropriate initialization vector to start its cryptographic operation. Since the initialization vector is derived from the synchronization information, the earth station can be fooled by false synchronizing information into generating past or future random streams and thus be manipulated as a captive earth station into performing decipherment.

A method is disclosed for preventing a particular form of data security penetration. The scenario is a cryptographic network (implying typically more than two stations in joint communication) which for other system purposes does transmit a date/ time value among the network's stations. If unauthorized access to one of the stations can be obtained during an expected period of outage (e.g., during shutdown overnight), then the following is possible:
1. By feeding the station (from some other mechanism) with a

false, old date/ time (in combination with whatever other,

control data are appropriate), the station would regenerate

the stream of decipher bits previously generated when the

date/ line was true. This bit stream can then be used to

decipher the data that were transmitted when the date/ time was

true and which was illicitly recorded for this later

deciphering.
2. Similarly, by feeding the station with a false, future date/

time, the station would generate, i.e., predict, the decipher

stream for later use when the date/ time is true. At that time

it would be necessary to capture the data being transmitted

and feed them, together with the predicted decipher stream,

into a mechanism performing the appropriate deciphering

process. This assumes that the penetrated station is not

accessible at the true date/ time.

A particular use of a transmitted date/ time is for enabling a station to join an existing communication among other network stations. In this case, it is not possible to establ...