0 if the arguments are invalid. 1 otherwise. Args: ctx: pointer to a context object initialized for validation. In/Out: pubkey: pointer to a public key object. pubkey will be set to an invalid value if this function returns 0. In: tweak32: pointer to a 32-byte tweak. If the tweak is invalid according to secp256k1_ec_seckey_verify, this function returns 0. For uniformly random 32-byte arrays the chance of being invalid is negligible (around 1 in 2^128).
Tweak a public key by multiplying it by a tweak value.