Method and apparatus for data encryption
First Claim
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1. A block cipher device for use in encrypting and decrypting information in a cryptographically secured digital communication system comprising:
- (a) a first stage adapted to receive an input data block and a control data block, said first stage comprising;
(i) a plurality of serially connected units including a sum modulo-two unit responsive to the input data block and a first subset of the control data block, and(ii) a first nibble swap unit responsive to the output signal from said sum modulo-two unit and a second subset of the control data block for reordering the output signal from said sum modulo-two unit;
(b) a key scheduler responsive to a key data block including means for randomizing the key data block; and
(c) a second stage adapted to receive the randomized key data block from said key scheduler in first and second key data sub-blocks, the control data block and the output signal from said first stage, said second stage comprising a plurality of serially connected units including;
(i) a first linear modulo unit responsive to said first key data sub-block from the key scheduler, the output signal from said first stage, and the control data block for performing a modulo summing operation based on a first modulus q,(ii) an nth power modulo unit responsive to the output signal from said first linear modulo unit for performing an nth power modulo operation based on a second modulus p to thereby provide an output signal of predetermined size, with n>
1 and with p=2K -X where X is selected such that the greatest common denominator between n and (2K -X-1) is one and K is said predetermined size, and(iii) a second linear modulo unit responsive to the second key data sub-block and the output signal from said nth power modulo unit for performing a modulo summing operation based on a third modulus r,said first, second, and third modulus p, q and r respectively being unique from each other.
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Abstract
A method and apparatus for use in encrypting and decrypting digital communications converting an initial block to final block based on freely selectable control information and secret key information. The apparatus or method having a plurality of units or steps operating on plain text or cipher text to provide a final block. The steps or methods including three modulo operations having unique modulus and meeting a specified constraint.
32 Citations
27 Claims
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1. A block cipher device for use in encrypting and decrypting information in a cryptographically secured digital communication system comprising:
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(a) a first stage adapted to receive an input data block and a control data block, said first stage comprising; (i) a plurality of serially connected units including a sum modulo-two unit responsive to the input data block and a first subset of the control data block, and (ii) a first nibble swap unit responsive to the output signal from said sum modulo-two unit and a second subset of the control data block for reordering the output signal from said sum modulo-two unit; (b) a key scheduler responsive to a key data block including means for randomizing the key data block; and (c) a second stage adapted to receive the randomized key data block from said key scheduler in first and second key data sub-blocks, the control data block and the output signal from said first stage, said second stage comprising a plurality of serially connected units including; (i) a first linear modulo unit responsive to said first key data sub-block from the key scheduler, the output signal from said first stage, and the control data block for performing a modulo summing operation based on a first modulus q, (ii) an nth power modulo unit responsive to the output signal from said first linear modulo unit for performing an nth power modulo operation based on a second modulus p to thereby provide an output signal of predetermined size, with n>
1 and with p=2K -X where X is selected such that the greatest common denominator between n and (2K -X-1) is one and K is said predetermined size, and(iii) a second linear modulo unit responsive to the second key data sub-block and the output signal from said nth power modulo unit for performing a modulo summing operation based on a third modulus r, said first, second, and third modulus p, q and r respectively being unique from each other. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method for converting an initial data block into a final data block for use in encrypting and decrypting information in a communication system comprising the steps of:
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(a) providing an initial data block, a control data block, a first key data block and a second key data block; (b) combining the initial data block and the control data block to provide a first data output signal; (c) transposing segments of the first data output signal responsively to a first subset of the control data block to provide a second data output signal; (d) expanding the second data output signal responsively to a third subset of the control data block to provide a third data output signal; (e) re-ordering the third data output signal responsively to a fourth subset of the control data block to provide a fourth data output signal; (f) combining the fourth data output signal with a first key data block to provide a fifth data output signal; (g) performing an nth power modulo operation using the fifth data output signal to provide a sixth data output signal; (h) combining a preselected portion of the sixth data output signal with a second key data block to provide a final data block. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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Specification