DIGITAL DATA SECURITY SYSTEM - Patent 0406291

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EP 0 406 291 A1

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(43)	Date of publication:
	09.01.1991 Bulletin 1991/02

(21)	Application number: 89904115.0

(22)	Date of filing: 20.03.1989

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International Patent Classification (IPC):

G11B 20/ 10^{( . )}
H04L 9/ 20^{( . )}

G11B 20/ 00^{( . )}
H04N 5/ 913^{( . )}

(86)	International application number:
	PCT/GB1989/000293

(87)	International publication number:
	WO 1989/008915 (21.09.1989 Gazette 1989/23)

(84)	Designated Contracting States:
	DE FR GB IT NL

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Priority:

18.03.1988 GB 19880006452

(71)	Applicant: IMPERIAL COLLEGE OF SCIENCE, TECHNOLOGY & MEDICINE
	London SW7 2AZ (GB)

(72)	Inventor:
	TURNER, Laurence, Frank Hertfordshire CM23 25U (GB)

(74)	Representative: Gadsden, Robert Edward
	3i Research Exploitation Limited The Gate House 2 Park Street Windsor Berkshire SL4 1LU Berkshire SL4 1LU (GB)

(54)	DIGITAL DATA SECURITY SYSTEM