Browse Prior Art Database

G3 Facsimile Image Data Encryption Method

IP.com Disclosure Number: IPCOM000099460D
Original Publication Date: 1990-Jan-01
Included in the Prior Art Database: 2005-Mar-14
Document File: 5 page(s) / 164K

Publishing Venue

IBM

Related People

Satoh, J: AUTHOR

Abstract

This article enables the encryption of facsimile data by using the NSF (Non-Standard Facility defined in the T.30), which provides the entry protocol to the proprietary procedure. In the 300 BPS binary procedure, the variable keyword is transmitted to the destination facsimile. Both the destination and originator facsimile have the user keyword with proper security control. Both keywords are concatenated in the facsimile and create the integrated keyword. The variable keyword changes for each facsimile transaction for safer data transmission. In the facsimile, the Encryption Operation Data Table is generated by integrated keyword by using the predefined data set.

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G3 Facsimile Image Data Encryption Method

       This article enables the encryption of facsimile data by
using the NSF (Non-Standard Facility defined in the T.30), which
provides the entry protocol to the proprietary procedure.  In the 300
BPS binary procedure, the variable keyword is transmitted to the
destination facsimile.  Both the destination and originator facsimile
have the user keyword with proper security control.  Both keywords
are concatenated in the facsimile and create the integrated keyword.
The variable keyword changes for each facsimile transaction for safer
data transmission.  In the facsimile, the Encryption Operation Data
Table is generated by integrated keyword by using the predefined data
set.  Once the Encryption Operation Data Table is generated, the
table is used repeatedly until all of the Exclusive OR operation is
processed for all image data (MR, MH, MMR) at both sides. In this
case, the EOL and all white or black lines are not processed.
    This article has the following characteristics.
    1.  If the variable keyword and the encrypted image data is
wire-tapped, the data transmission is safe, since it needs both
keywords to generate the Encryption Operation Data Table.

      2.  The encrypted data always changes for each document;
therefore, it is very difficult to analyze the Encryption Operation
Data Table on the image data by statistical method.

      3.  The difficulty in analyzing the user keyword is greater
than that of an original method, such as DES, since the Encryption
Operation Data itself is difficult to analyze.

      4.  The encode and decode process is simple enough (Exclusive
OR) for the facsimile MPU to to process the total image data within
reasonable timing.  Of course, the generation of the encryption
operation data takes time, but it must be done only for very short
data set. (ED1 is the range of 64 to 256 bytes practically.)

      5.  This encryption process will be efficient if the algorithm
is embedded into the software of compression/decompression.

      6.  No special hardware is required, if the facsimile has
reasonable MPU power. PRIOR ART (Fig. 1)

      In general, the conventional technology requires the hardware
cipher equipment 1 and 2 to encrypt the data to the communication
line.  The cipher equipment encrypts the data with DES cipher
architecture, for example.  But, this equipment cannot be used
directly for the G3 facsimile for the following reasons:

      -  This equipment requires the RS232C or other standard
interface which needs the additional special hardware on G3
facsimile. .AB -  The cipher equipment is only useful in the case of
error- free protocol.  G3 protocol has no error retry except the ECM
(Error Correction Mode), and it is re-synchronized by the EOL code.
GENERAL DESCRIPTION OF THE INVENTION
    A. Keyword control (Figs. 2 and 3)
    The secret user keyword XU 1 will be used for both ends. ...