Browse Prior Art Database

Securing a Master Key in Cryptographic Devices

IP.com Disclosure Number: IPCOM000087136D
Original Publication Date: 1976-Dec-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Ehrsam, WF: AUTHOR [+2]

Abstract

Master cipher key security is attained by storing the master key in a volatile memory mounted on the same circuit card as the block cipher device. This arrangement safeguards the master key against disclosure to unauthorized persons by causing the master key information to be lost if the card is pulled from the using product, since removal of the card causes the volatile memory to lose its power.

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Securing a Master Key in Cryptographic Devices

Master cipher key security is attained by storing the master key in a volatile memory mounted on the same circuit card as the block cipher device. This arrangement safeguards the master key against disclosure to unauthorized persons by causing the master key information to be lost if the card is pulled from the using product, since removal of the card causes the volatile memory to lose its power.

The master key used in a block cipher function is stored in a volatile memory, such as a CMOS random access memory which is powered by a battery. The power requirements for a CMOS random access memory is relatively small so that a small nonchargeable battery, e.g., a mercury battery, can be used to maintain master key information for long periods of time. The master key CMOS memory is mounted on the same printed circuit card as the block cipher device and its power supply requirements are met by the battery via pins on the card connector, as shown. If the card containing the block cipher device with the CMOS memory is pulled from the gate of the using product by an unauthorized person, the master key information is lost as the volatile memory loses its power supply.

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