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EPFL-IC-IIF-LACAL Marcelo E. Kaihara April 27 th, 2007 Algorithms for public-key cryptology Montgomery Arithmetic
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RSA: ElGamal: Motivation Need of efficient algorithms for modular multiplication Most of the time computing modular multiplications
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Radix representation Notation Multiple-precision integer arithmetic depending on the processor (normalized)
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General overview Ordinary RepresentationMontgomery Representation Sequential multiplications performed in Montgomery representation Montgomery Multiplication
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Isomorphic Ordinary RepresentationMontgomery Representation Montgomery radix Montgomery Multiplication
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Definition Definition:
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How to compute? Algorithm
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How to compute? Algorithm
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How to compute? Algorithm
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How to compute? Algorithm
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How to compute? Algorithm
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How to compute? Algorithm
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How to compute? Algorithm
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How to compute? Algorithm
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How to compute? Algorithm
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How to compute? Algorithm
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How to compute? Algorithm
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How to compute? Algorithm
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How to compute? Algorithm
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How to compute? Algorithm
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How to compute? Algorithm
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How to compute? Algorithm
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How to compute? Algorithm
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How to compute? Algorithm
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How to compute? Algorithm
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How to compute? Algorithm
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How to compute? Algorithm
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How to compute? Algorithm
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How to compute? Algorithm
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How to compute? Algorithm
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How to compute?
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Subtraction-less Montgomery multiplication Algorithm
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Subtraction-less Montgomery multiplication Algorithm
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Subtraction-less Montgomery multiplication Algorithm
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Ordinary RepresentationMontgomery Representation Conversion back and forth from ordinary representation and Montgomery representation
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How to compute R 2 mod m ? Ordinary RepresentationMontgomery Representation Montgomery Bootstrapping
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What about modular inversion? Ordinary RepresentationMontgomery Representation Montgomery Bootstrapping
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How to compute m 0 -1 mod B? Montgomery Bootstrapping 0 011 0 001 0 011 0 010 1 001 00 011 0 011 1 001 0 011 0 011 1 000 0 001 010 1 011 0 100
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0 011 0 001 0 011 0 010 1 001 00 011 0 011 1 001 0 011 0 011 1 000 0 001 010 1 011 0 100
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Montgomery Squaring
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RSA pseudorandom bit generator
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