Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

In-Band Delivery of Scrambling Keys in Fixed Format Data

IP.com Disclosure Number: IPCOM000101410D
Original Publication Date: 1990-Aug-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 3 page(s) / 137K

Publishing Venue

IBM

Related People

Smith, PR: AUTHOR

Abstract

This disclosure presents a programming method which can be used to permit encryption keys or seed values for random number scrambling of data, to be delivered in-band (i.e., using the same medium) as the scrambled data, without altering the format of the data. Conditionally, the format of the data should provide no additional means of transporting the key values, primarily for existing format media, and data must consist of many small units or blocks of data that are individually recoverable. Also required is the use of independent keys per unit of data; such keys should be independent of the physical medium.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 43% of the total text.

In-Band Delivery of Scrambling Keys in Fixed Format Data

       This disclosure presents a programming method which can
be used to permit encryption keys or seed values for random number
scrambling of data, to be delivered in-band (i.e., using the same
medium) as the scrambled data, without altering the format of the
data.  Conditionally, the format of the data should provide no
additional means of transporting the key values, primarily for
existing format media, and data must consist of many small units or
blocks of data that are individually recoverable.  Also required is
the use of independent keys per unit of data;  such keys should be
independent of the physical medium.  The method permits the
distribution of an information product from a provider to a consumer
using a secure Key-Encyphering Key (KEK) distribution path and an
existing information path to carry the product in such a way that
only consumers knowing the KEK can correctly recover the bulk of the
information and, random access is provided to small units of the
information each with an unpredictable key, with reference only to
the contents of the data unit and the KEK value.

      An example of the problem solved by this disclosure is that of
digitally recorded music on Compact Disc (CD).  The format of data on
the CD is standardized, components to read and process the data are
available in quantity so that if it is required to encipher or
scramble the data, it will be beneficial to do so without changing
the format.  The format of CD music data is as follows:
      The smallest block of data is called a 'frame'.  This
      consists of a few bits of control information, 24 bytes
      of data with 8 bytes of error correcting code.  A
      sequence of 98 frames is a 'sector'.  The first frame
      of a sector contains a short header giving the sector
      identification followed by 8 bytes of encoded music.
      The remaining 97 frames contain encoded music data (24
      bytes each).  Sectors are read and 'performed' at a
      rate of 75 sectors per second by reading at constant
      velocity from the surface.

      The value of an isolated frame from a music CD is very small,
so it is possible to record the first frame of each sector in clear
(without encryption or scrambling), and in fact it is advantageous to
do so because the control information in the first frame consists of
a synchronizing pattern and hardware address of the sector which
should be interpreted without decipherment or unscrambling.  The CD
player provides random access to each sector; thus, it must be
possible to re- synchronize the unscrambling at any sector.

      CONVENTIONAL SCRAMBLING: Two possibilities for the basic
scrambling mechanism are:
1.   Use of a stream cipher.  This technique provides confidentiality
for the enciphered data.
2.   'Cut-point' Scrambling as used in the Satellite Television MAC
standa...