US5046069A
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Data integrity securing means
Assignee: International Business Machines Corp
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Filing: 1988-10-17
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Granted: 1991-09-03
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Expires: 2008-10-17
Abstract
Abstract A process for updating the frame check sequence FCS r (X) of a digital frame including an embedded variable header polynomial H r (x), said process including: partitioning H r (x); XORing the modified polynomial header H t (x) and previous polynomial header H r (x) to generate a differential polynomial D(x); computing a differential frame check polynomial sequence dFCS (x) on said D(x) only and adding dFCS (x) to the polynomial FCS r (x) to form a new FCS t (x).
Inventors
- 👤 Jean Calvignac
- 👤 Michel Dauphin
- 👤 Raymond Lenoir
- 👤 Jean-Louis Picard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 14:20
CPC Classifications
H; H03; H03M; H03M13/00; H03M13/03; H03M13/05; H03M13/09; H03M13/093; H04; H04L; H04L1/00; H04L1/0078; H04L1/0083
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
136 words
A process for updating the frame checking sequence (FCS) of a data frame including a polynomial information section I(x), a polynomial header section H r (x) and the FCS corresponding to the Remainder of the polynomial division of I(x)+H r (x) by a predetermined polynomial generator G(x), with the operations being performed in the Galois field, said process including: partitioning the frame into the polynomial header section H r (x) to be varied into H t (x) and the polynomial information section I(x) to be kept unchanged; computing a difference or variation polynomial D(x) over header sections H r (x) and H t (x) only. D(x)=H.sub.t (x)-H.sub.r (x); computing a differential FCS dFCS(x)=Remainder |D(x) x 16 , G(x)); and adding the differential FCS to an original FCS r (x) to generate an updated FCS, (i.e. FCS).
Claim 2
Dependent Claim
136 words
A process for updating the frame checking sequence (FCS) of a data frame including a polynomial information section I(x), a polynomial header section H r (x) and the FCS corresponding to the Remainder of the polynomial division of I(x)+H r (x) by a predetermined polynomial generator G(x), with the operations being performed in the Galois field, said process including: partitioning the frame into the polynomial header section H r (x) to be varied into H t (x) and the polynomial information section I(x) to be kept unchanged; computing a difference or variation polynomial D(x) over header sections H r (x) and H t (x) only. D(x)=H.sub.t (x)-H.sub.r (x); computing a differential FCS dFCS(x)=Remainder |D(x) x 16 , G(x)); and adding the differential FCS to an original FCS r (x) to generate an updated FCS, (i.e. FCS).
Claim 3
Dependent Claim
21 words
A process according to claim 1 wherein said differential FCS is computed on a bit-by-bit basis over said difference polynomial D(x).
Claim 4
Dependent Claim
158 words
A process for updating the frame checking sequence (FCS) of a data frame including a polynomial information section I(x) to be kept unchanged, a polynomial header section H r (x) being a two bytes long word starting at the n th byte position of said data frame (including FCS), to be varied into H t (x) and the FCS corresponding to the Remainder of the polynomial division of I(x)+H r (x) by a predetermined polynomial generator G(x), with the operations being performed in the Galois field, said process including: computing a difference or variation polynomial, D(x)=H.sub.t (x)-H.sub.r (x); computing a differential FCS (dFCS(x)), with said dFCS(x) further including computing the Remainder R(x) of the polynomial division of x 8n by G(x); multiplying said Remainder R(x) by D'(x); wherein D'(x) is the polynomial such that D(x)=D'(x)×x 8 ×n-16 ; and adding the differential FCS to the original FCS r (x) to generate the updated FCS, (i.e. FCS t ).
Claim 5
Dependent Claim
158 words
A process for updating the frame checking sequence (FCS) of a data frame including a polynomial information section I(x) to be kept unchanged, a polynomial header section H r (x) being a two bytes long word starting at the n th byte position of said data frame (including FCS), to be varied into H t (x) and the FCS corresponding to the Remainder of the polynomial division of I(x)+H r (x) by a predetermined polynomial generator G(x), with the operations being performed in the Galois field, said process including: computing a difference or variation polynomial, D(x)=H.sub.t (x)-H.sub.r (x); computing a differential FCS (dFCS(x)), with said dFCS(x) further including computing the Remainder R(x) of the polynomial division of x 8n by G(x); multiplying said Remainder R(x) by D'(x); wherein D'(x) is the polynomial such that D(x)=D'(x)×x 8 ×n-16 ; and adding the differential FCS to the original FCS r (x) to generate the updated FCS, (i.e. FCS t ).
Claim 6
Dependent Claim
79 words
A process according to claim 3 wherein said n th byte location is expressed in its binary form ##EQU14## with n i =0 or 1 and m being the highest bit weight of n; and said differential FCS computing operation includes: computing "bit Remainders" of the polynomial division of x 8 ×2.spsp.i by G(x) for each value of i=0 to m for which n i =1; multiplying said bit Remainders together; and, multiplying by D'(x) said multiplied bit Remainders.
Claim 7
Dependent Claim
14 words
A process according to claim 4 wherein said "bit" Remainders are precomputed and stored.
Claim 8
Independent Claim
173 words
A device for updating into FCS t the frame checking sequence (FCS r ) of a data frame including a variable header, to be varied from an O(x) polynomial into a N(x) polynomial located at the n th byte position of the frame, said updating using a polynomial generator G(x), said device including: first XOR means for performing D'(x)=N(x) ⊕O(x) storage means storing so called bit Remainders representing the remainders of predetermined values of x 8 ×.spsp.i by G(x); addressing means for addressing said storage means; means for storing into said addressing means a binary expression of ##EQU15## and fetching sequentially from said storage means said bit-Remainders for each storage location corresponding to n i =1; First multiplier means connected to said storage means for multiplying said fetched bit Remainders with each other; second multiplier means connected to said first multiplier means and to said XOR means providing D'(x); and, adding means connected to said second multiplier means for adding said second multiplier output to said FCS r and derive FCS t therefrom.
Claim 9
Independent Claim
173 words
A device for updating into FCS t the frame checking sequence (FCS r ) of a data frame including a variable header, to be varied from an O(x) polynomial into a N(x) polynomial located at the n th byte position of the frame, said updating using a polynomial generator G(x), said device including: first XOR means for performing D'(x)=N(x) ⊕O(x) storage means storing so called bit Remainders representing the remainders of predetermined values of x 8 ×.spsp.i by G(x); addressing means for addressing said storage means; means for storing into said addressing means a binary expression of ##EQU15## and fetching sequentially from said storage means said bit-Remainders for each storage location corresponding to n i =1; First multiplier means connected to said storage means for multiplying said fetched bit Remainders with each other; second multiplier means connected to said first multiplier means and to said XOR means providing D'(x); and, adding means connected to said second multiplier means for adding said second multiplier output to said FCS r and derive FCS t therefrom.
Claim 10
Independent Claim
173 words
A device for updating into FCS t the frame checking sequence (FCS r ) of a data frame including a variable header, to be varied from an O(x) polynomial into a N(x) polynomial located at the nth byte position of the frame, said updating using a polynomial generator G(x), said device including: first XOR means for performing D'(x)=N(x) (XOR)O(x) storage means storing so called bit Remainders representing the remainders of predetermined values of x 8 .2.spsp.i by G(x); addressing means for addressing said storage means; means for storing into said addressing means a binary expression of ##EQU16## and fetching sequentially from said storage means said bit Remainders for each storage location corresponding to n i =1; first multiplier means connected to said storage means for multiplying said fetched bit Remainders with each other; second multiplier means connected to said first multiplier means and to said XOR means providing D'(x); and adding means connected to said second multiplier means for adding said second multiplier output to said FCS r and derive FCS t therefrom.
Claim 11
Independent Claim
173 words
A device for updating into FCS t the frame checking sequence (FCS r ) of a data frame including a variable header, to be varied from an O(x) polynomial into a N(x) polynomial located at the nth byte position of the frame, said updating using a polynomial generator G(x), said device including: first XOR means for performing D'(x)=N(x) (XOR)O(x) storage means storing so called bit Remainders representing the remainders of predetermined values of x 8 .2.spsp.i by G(x); addressing means for addressing said storage means; means for storing into said addressing means a binary expression of ##EQU16## and fetching sequentially from said storage means said bit Remainders for each storage location corresponding to n i =1; first multiplier means connected to said storage means for multiplying said fetched bit Remainders with each other; second multiplier means connected to said first multiplier means and to said XOR means providing D'(x); and adding means connected to said second multiplier means for adding said second multiplier output to said FCS r and derive FCS t therefrom.
References Cited (Backward Citations)
WO1980002611A1
Cited
US4723244A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-09-02 | 1995-03-04 | 1995-09-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-09-02 | 1999-03-04 | 1999-09-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-09-02 | 2003-03-04 | 2003-09-03 | $7700.00 | Window Closed / Lapsed |