Export SHA256 functions #447

1. 
   chfast commented at 9:51 am on March 13, 2017: none
2. Export SHA256 functions 6cec601d03
3. chfast force-pushed on Mar 13, 2017
4. dcousens approved
5. 
   dcousens commented at 11:00 am on March 21, 2017: contributor

   utACK
6. 
   laanwj commented at 12:57 pm on March 21, 2017: member

   Should SHA256 functions be part of the library’s API? The library is secp256k1, not sha256lib, there are plenty of libraries available that export SHA256.

   I think we should avoid exporting internal implementation details. This reduces the flexibility to change things in the future.

7. 
   chfast commented at 1:04 pm on March 21, 2017: none

   Why would you like to have 2 implementations of SHA256 in your codebase if you need both secp256k1 and SHA256? This increases code size and decreases performance.
8. 
   sipa commented at 5:43 pm on March 21, 2017: contributor

   Sorry, NACK. libsecp256k1 is a library for elliptic curve crypto, not a generic cryptography library. It has a copy of SHA256 for randomization and a few related algorithms, but it is not optimized in any way. I fear that exposing the function will lead to people demanding that it gets optimized for various purposes and/or platforms, which I don’t think should be the library’s focus.

   If code size matters that much to you (SHA256 is only a few kB), perhaps we should provide a way for libsecp256k1 to be compiled using an external SHA256 implementation instead.

9. 
   dcousens commented at 9:24 pm on March 21, 2017: contributor

   If code size matters that much to you (SHA256 is only a few kB), perhaps we should provide a way for libsecp256k1 to be compiled using an external SHA256 implementation instead.

   For me, supporting exporting SHA256 here was purely for the purposes of ensuring a consistent implementation being used. [not to doubt the quality of any implementation]

   Providing the above would resolve my concern.

10. sipa closed this on Mar 21, 2017

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11. real-or-random cross-referenced this on Jul 22, 2020 from issue Add schnorrsig module which implements BIP-340 compliant signatures by jonasnick

Contributors
chfast dcousens laanwj sipa