From 626a8d8d3df8880991684d6d1a06b82f6685b51a Mon Sep 17 00:00:00 2001 From: vnugent Date: Sun, 28 Jan 2024 19:23:18 -0500 Subject: initial commit --- include/secp256k1_ecdh.h | 63 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 63 insertions(+) create mode 100644 include/secp256k1_ecdh.h (limited to 'include/secp256k1_ecdh.h') diff --git a/include/secp256k1_ecdh.h b/include/secp256k1_ecdh.h new file mode 100644 index 0000000..4d9da34 --- /dev/null +++ b/include/secp256k1_ecdh.h @@ -0,0 +1,63 @@ +#ifndef SECP256K1_ECDH_H +#define SECP256K1_ECDH_H + +#include "secp256k1.h" + +#ifdef __cplusplus +extern "C" { +#endif + +/** A pointer to a function that hashes an EC point to obtain an ECDH secret + * + * Returns: 1 if the point was successfully hashed. + * 0 will cause secp256k1_ecdh to fail and return 0. + * Other return values are not allowed, and the behaviour of + * secp256k1_ecdh is undefined for other return values. + * Out: output: pointer to an array to be filled by the function + * In: x32: pointer to a 32-byte x coordinate + * y32: pointer to a 32-byte y coordinate + * data: arbitrary data pointer that is passed through + */ +typedef int (*secp256k1_ecdh_hash_function)( + unsigned char *output, + const unsigned char *x32, + const unsigned char *y32, + void *data +); + +/** An implementation of SHA256 hash function that applies to compressed public key. + * Populates the output parameter with 32 bytes. */ +SECP256K1_API const secp256k1_ecdh_hash_function secp256k1_ecdh_hash_function_sha256; + +/** A default ECDH hash function (currently equal to secp256k1_ecdh_hash_function_sha256). + * Populates the output parameter with 32 bytes. */ +SECP256K1_API const secp256k1_ecdh_hash_function secp256k1_ecdh_hash_function_default; + +/** Compute an EC Diffie-Hellman secret in constant time + * + * Returns: 1: exponentiation was successful + * 0: scalar was invalid (zero or overflow) or hashfp returned 0 + * Args: ctx: pointer to a context object. + * Out: output: pointer to an array to be filled by hashfp. + * In: pubkey: pointer to a secp256k1_pubkey containing an initialized public key. + * seckey: a 32-byte scalar with which to multiply the point. + * hashfp: pointer to a hash function. If NULL, + * secp256k1_ecdh_hash_function_sha256 is used + * (in which case, 32 bytes will be written to output). + * data: arbitrary data pointer that is passed through to hashfp + * (can be NULL for secp256k1_ecdh_hash_function_sha256). + */ +SECP256K1_API SECP256K1_WARN_UNUSED_RESULT int secp256k1_ecdh( + const secp256k1_context *ctx, + unsigned char *output, + const secp256k1_pubkey *pubkey, + const unsigned char *seckey, + secp256k1_ecdh_hash_function hashfp, + void *data +) SECP256K1_ARG_NONNULL(1) SECP256K1_ARG_NONNULL(2) SECP256K1_ARG_NONNULL(3) SECP256K1_ARG_NONNULL(4); + +#ifdef __cplusplus +} +#endif + +#endif /* SECP256K1_ECDH_H */ -- cgit