Montgomery reduction: Difference between revisions
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Library-based computation of x1 ^ x2 mod m : |
Library-based computation of x1 ^ x2 mod m : |
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151232511393500655853002423778 |
151232511393500655853002423778 |
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</pre> |
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=={{header|Sidef}}== |
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{{trans|zkl}} |
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<lang ruby>func montgomeryReduce(m, a) { |
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{ |
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a += m if a.is_odd |
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a >>= 1 |
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} * m.as_bin.len |
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a % m |
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} |
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var m = 750791094644726559640638407699 |
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var t1 = 323165824550862327179367294465482435542970161392400401329100 |
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var r1 = 440160025148131680164261562101 |
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var r2 = 435362628198191204145287283255 |
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var x1 = 540019781128412936473322405310 |
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var x2 = 515692107665463680305819378593 |
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say("Original x1: ", x1) |
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say("Recovererd from r1: ", montgomeryReduce(m, r1)) |
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say("Original x2: ", x2) |
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say("Recovererd from r2: ", montgomeryReduce(m, r2)) |
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print("\nMontgomery computation of x1^x2 mod m: ") |
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var prod = montgomeryReduce(m, t1/x1) |
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var base = montgomeryReduce(m, t1) |
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for (var exponent = x2; exponent ; exponent >>= 1) { |
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prod = montgomeryReduce(m, prod * base) if exponent.is_odd |
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base = montgomeryReduce(m, base * base) |
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} |
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say(montgomeryReduce(m, prod)) |
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say("Library-based computation of x1^x2 mod m: ", x1.powmod(x2, m))</lang> |
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{{out}} |
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<pre> |
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Original x1: 540019781128412936473322405310 |
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Recovererd from r1: 540019781128412936473322405310 |
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Original x2: 515692107665463680305819378593 |
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Recovererd from r2: 515692107665463680305819378593 |
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Montgomery computation of x1^x2 mod m: 151232511393500655853002423778 |
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Library-based computation of x1^x2 mod m: 151232511393500655853002423778 |
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</pre> |
</pre> |
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