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Updated constantTimeIsEqual to use binary addition to address a possible issue of summing up negative and positive sub-results of XOR operations to 0.
#21
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...to address a possible issue of summing up negative and positive sub-results of XOR operations to `0`.
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Related to #1
I think the current implementation of
constantTimeIsEqualmight have an issue:The
r + (ab._1 ^ ab._2)part is not exactly the same asresult |= a[i] ^ b[i]from the article, as it uses addition of signed bytes as opposed to binary addition (OR), where sign does not matter.So it is possible to get say a
1and a-1via XORing and then add them up to a0.Array(-3,-2,4,1).sumis also 0, butArray(-3,-2,4,1).foldLeft(0){ (r,n) => r | n }is not. Hope this illustrates the point.PS. Just noticed deprecation warning. Keeping PR open for anyone who wants to use/fork the library.