Is there any way to calculate (a mod c)*(b mod c)?
Knowing only:
a*bcd((a mod c)*(b mod c)) mod c(a mod d)*(b mod d)
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2I think this is a question more relevant to ask in the Math Exchange community. – M.K Mar 01 '19 at 19:23
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Then I'll try there too. – tsurt Mar 01 '19 at 19:24
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Are you asking for the algorithm or what? – DaBler Mar 01 '19 at 19:24
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I'm just curious is this possible. – tsurt Mar 01 '19 at 19:25
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4I'm voting to close this question as off-topic because it is not about programming. – High Performance Mark Mar 01 '19 at 19:50
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The last three "knowns" seem to be redundant. – Beta Mar 02 '19 at 04:08
1 Answers
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No, it's impossible.
Here's a counterexample:
ab = 1225 = (5)(5)(7)(7)
c = 3
d = 5000
((a mod c)(b mod c)) mod c = 1
(a mod d)(b mod d) = 1225
If a=25 and b=49, then (a mod c)(b mod c)=(1)(1)=1
If a=35 and b=35, then (a mod c)(b mod c)=(2)(2)=4
Beta
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