Patent US5121429A successfully refreshed from Google Patents.
US5121429A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Digital signal processing
Assignee: HATFIELD POLYTECHNIC
•
Filing: 1989-07-05
•
Granted: 1992-06-09
•
Expires: 2009-07-05
Abstract
Abstract For more convenient mechanisation, the modulo m reduction of a binary number P can be carried out by conditionally summing the modulo m reductions of a power series of two and then modulo m reducing the sum. The modulo m reductions of the series, called the `residues` of the series, can be pre-calculated and stored but this may be inconvenient if they are long in terms of numbers of bits. Herein, the residues are calculated in sequence by a recursive process, each residue being calculated from the next preceeding one, this leading to a `serial` arrangement for generating the residues which can be incorporated into a serial modulo m reduction unit. Such a serial modulo m reduction unit is convenient for implementation as an integrated circuit especially as part of an overall circuit for encryption and decryption of digital signals.
Inventors
- 👤 John R. Guppy
- 👤 Paul A. Findlay
- 👤 Brian A. Johnson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 10:56
CPC Classifications
G; G06; G06F; G06F7/00; G06F7/60; G06F7/72; G06F7/722; H; H04; H04L; H04L9/00; H04L9/30; H04L9/3006; H04L9/302; G06F7/38; G06F7/48; G06F7/499; G06F7/49931; G06F7/723; H04L2209/00; H04L2209/12; H04L2209/122; H04L2209/125
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
158 words
A method for the encryption or decryption of an original digital signal comprising: making the bits of said signal avaiable in sequence; squaring each bit of a chosen multiple bit digital exponent using bit serial multiplier means to square said signal and conditionally multiplying a result of the squaring step by the original signal in dependence upon the respective bit values of said chosen multiple bit digital exponent, and carrying out a modulo m reduction of a result of each operation carried out by the multiplier means by calculating a series of residue values comprising modulo m reductions of ascending powers of two are in sequence, each being calculated from the valve of a preceding calculation in a recursive process, and said residue values are conditionally summed in dependence upon the bit values of said binary number to give a sum of said residue values, which sum is indicative of said modulo m reduction of said binary number.
Claim 2
Independent Claim
158 words
A method for the encryption or decryption of an original digital signal comprising: making the bits of said signal avaiable in sequence; squaring each bit of a chosen multiple bit digital exponent using bit serial multiplier means to square said signal and conditionally multiplying a result of the squaring step by the original signal in dependence upon the respective bit values of said chosen multiple bit digital exponent, and carrying out a modulo m reduction of a result of each operation carried out by the multiplier means by calculating a series of residue values comprising modulo m reductions of ascending powers of two are in sequence, each being calculated from the valve of a preceding calculation in a recursive process, and said residue values are conditionally summed in dependence upon the bit values of said binary number to give a sum of said residue values, which sum is indicative of said modulo m reduction of said binary number.
Claim 3
Dependent Claim
90 words
A method according to claim 1, wherein each said sum of residue values other than a final sum of residues indicative of a fully encrypted or decrypted signal, is returned without further reduction to said multiplier means and only a final sum of residues is subjected to a modulo m reduction operation by a modulo m, said multiplier means having a bit capacity greater than a number of bits of the modulus m by an amount sufficient to handle properly said sum of residue values other than the final sum.
Claim 4
Dependent Claim
158 words
Apparatus for the encryption/decryption of an original digital signal comprising: means for presenting bits of said digital signal in sequence; means for presenting bits of a chosen multiple bit digital exponent in sequence; bit serial multiplier means operable, for each said bit of said exponent, to square said signal and conditionally multiplying a result of the squaring operation by the original signal in dependence upon the respective bit value of the exponent; and modulo m reduction means for performing a modulo m reduction on the result of each operation by the multiplier means including calculating means for making calculations to determine respective ones of a series of residue values comprising modulo m reductions of ascending powers of two, the calculating means being operable for determining each residue value from a value determined by a preceding calculation in a recursive process, and summing means for conditionally summing said residue values in dependence upon bit values of said binary number.
Claim 5
Dependent Claim
158 words
Apparatus for the encryption/decryption of an original digital signal comprising: means for presenting bits of said digital signal in sequence; means for presenting bits of a chosen multiple bit digital exponent in sequence; bit serial multiplier means operable, for each said bit of said exponent, to square said signal and conditionally multiplying a result of the squaring operation by the original signal in dependence upon the respective bit value of the exponent; and modulo m reduction means for performing a modulo m reduction on the result of each operation by the multiplier means including calculating means for making calculations to determine respective ones of a series of residue values comprising modulo m reductions of ascending powers of two, the calculating means being operable for determining each residue value from a value determined by a preceding calculation in a recursive process, and summing means for conditionally summing said residue values in dependence upon bit values of said binary number.
Claim 6
Independent Claim
126 words
A method of encrypting a block of text, comprising the steps of: inputting a block of text to be encrypted; producing numbers indicative of said block of text; performing a modulo m reduction of said numbers, by a) calculating a series of residue values in sequence, said residue values comprising modulo m reductions of ascending powers of two, each being calculated from values of preceding calculating on preceding numbers which represent preceding blocks of said text, in a recursive process, and b) summing said residue values to give a sum of said residue values dependent upon values of said numbers, which sum is indicative of said modulo m reduction of said numbers; and outputting encrypted text based on values obtained in said performing a reduction step.
Claim 7
Independent Claim
126 words
A method of encrypting a block of text, comprising the steps of: inputting a block of text to be encrypted; producing numbers indicative of said block of text; performing a modulo m reduction of said numbers, by a) calculating a series of residue values in sequence, said residue values comprising modulo m reductions of ascending powers of two, each being calculated from values of preceding calculating on preceding numbers which represent preceding blocks of said text, in a recursive process, and b) summing said residue values to give a sum of said residue values dependent upon values of said numbers, which sum is indicative of said modulo m reduction of said numbers; and outputting encrypted text based on values obtained in said performing a reduction step.
Claim 8
Dependent Claim
92 words
A method according to claim 4, wherein for each bit p 1 of said number there is formed an associated residue value r 1 equal to 2r 1-1 if (2r 1-1 -m ) is less than zero or to (2r 1-1 -m) if (2r 1-1 -m) is greater than zero, said residue values being formed in sequence and r 1-1 being the value formed before r 1 , and wherein the residue values associated with bits of the number having logic one values are summed to form said sum of residue values.
Claim 9
Dependent Claim
117 words
Apparatus for encrypting text, comprising: means for inputting a block of text to be encrypted; means for producing numbers which represent indicative of said block of text; calculating means for calculating respective ones of a series of residue values comprising modulo m reductions of ascending powers of two or said numbers, the calculating means being operable for determining each of said respective ones of said residue values from a values determined by a preceding calculation in a recursive process, and summing means for summing said respective ones of said residue values to product a summed value in dependence upon values of said numbers; and means for producing encrypted text based on values calculated by said calculating means.
Claim 10
Dependent Claim
117 words
Apparatus for encrypting text, comprising: means for inputting a block of text to be encrypted; means for producing numbers which represent indicative of said block of text; calculating means for calculating respective ones of a series of residue values comprising modulo m reductions of ascending powers of two or said numbers, the calculating means being operable for determining each of said respective ones of said residue values from a values determined by a preceding calculation in a recursive process, and summing means for summing said respective ones of said residue values to product a summed value in dependence upon values of said numbers; and means for producing encrypted text based on values calculated by said calculating means.
References Cited (Backward Citations)
US4759064A
Cited
US4841570A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-06-09 | 1995-12-09 | 1996-06-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-06-09 | 1999-12-09 | 2000-06-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-06-09 | 2003-12-09 | 2004-06-09 | $7700.00 | Window Closed / Lapsed |