I am using GMP[https://gmplib.org] for implementation of cryptographic algorithms, especially for big integer/finite field arithmetic. However, I got the comment that GMP is not constant time, therefore it is not a good choice in for cryptographic implementations. But I wonder
1. Why GMP is not constant time?
2. And what makes the difference than any constant time bignum library?
3. Is there any general purpose constant time big number library for C/C++ especially targeted for Cryptographic use?
My understanding is addition, subtraction, multiplication, and division implemented in C do not depends on the size of the input. Therefore, such operations on any platform are constant time. Now it seems I'm completely wrong.
Dear Md Al-Amin Khandaker,
Below mentioned link may be useful for your clarifications
https://crypto.stanford.edu/pbc/
@Balaji Chandrasekaran, what I found is just why the developer chooses GMP and C than any other tools to write PBC. I can not find anything about why GMP is not constant time. Would you please send a more specific link where the constant time is written?
@Aparna Sathya Murthy, what do you mean by "laws for large #s "? What is "#s" stands for? Please tell me little more details.
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