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Is this half-smart way of verifying EdDSA signature secure?

Well, the checking procedure itself is not SUF-CMA as one can generate a second valid signature by replacing $R$ with $R+I$ where $I$ is a point of order divisible by 4. By not checking the $X$ ...
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3 votes

Straightforward modular arithmetic for power-of-two moduli

Why if $q$ is a power-of-two integer, then doing arithmetic modulo $q$ (addition and multiplication) is very efficient and straightforward? Because processors already have efficient addition and ...
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1 vote

Are there prime numbers that are easy to modulo within 40 bits to 60 bits?

I want to implement LWE-based encryption scheme, the modulo $q$ could be decomposed as $q = q_0\cdot q_1\cdots q_k$ according to CRT. Actually, for CRT to work, all that is necessarily is that the ...
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10 votes

Are there prime numbers that are easy to modulo within 40 bits to 60 bits?

First, this is obviously true with no restrictions on $b$. For example, for $b = 2^n-2$ we get that $2^n - b = 2^n - (2^n-2) = 2$ is prime. This is boring, and likely not what you mean (and instead, I ...
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