How to use curve APIs when built and installed? #1630

1. 
   lightbulb128 commented at 2:24 am on November 4, 2024: none

   I want to use the curve api, e.g. struct secp256k1_scalar, secp256k1_gej, secp256k1_ecmult_gen, etc., in my code, but when the library is installed, it only produce high-level headers. Is there some extra flags I should give to CMake so that the headers like “field.h”, “group.h” will be installed?
2. 
   lightbulb128 commented at 3:10 am on November 4, 2024: none

   Plus, when I include “field.h” in my C++ code and compile, it gives an error:

   0.../secp256k1/util.h: In function ‘int secp256k1_memcmp_var(const void*, const void*, size_t)’:
   1.../secp256k1/util.h:222:31: error: invalid conversion from ‘const void*’ to ‘const unsigned char*’ [-fpermissive]
   2  222 |     const unsigned char *p1 = s1, *p2 = s2;
   3      |                               ^~
   4      |                               |
   5      |                               const void*
   

   How can I use this library’s low-level curve code with C++?

3. 
   sipa commented at 3:42 am on November 4, 2024: contributor

   libsecp256k1 is a high-level library; it only exposes functions needed for ECDSA/ECDH/BIP340 and a few more protocols, not low-level scalar, field, or group operations.

   It is of course open-source, and you’re welcome to use the internals directly as you see fit. Note that it is written in C, not C++, so directly using the implementation code in C++ will likely not work.

4. 
   lightbulb128 commented at 3:47 am on November 4, 2024: none

   Thank you for the quick reply. I will try to figure out a way.
5. lightbulb128 closed this on Nov 4, 2024

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