pkey_meth_derive: to derive a shared symmetric key from two ECC keys
pkey_meth_public_raw: to get the raw form of the public key
import_public_ec_raw: to import the raw form of the public key
generate_p256_keypair: key generation for the P-256 curve
With `gcc-12 -Wstrict-prototypes` the following warning is shown:
crypto.c:43:13: warning: function declaration isn't a prototype [-Wstrict-prototypes]
43 | static BIO* new_memory_BIO() {
| ^~~~~~~~~~~~~~
This fixes the signature parsing and building to work correctly. Sometimes
a signature was one or two bytes too short, and needed to be padded. OpenSSL
can do this for us.
In Lua 5.3 LUAL_BUFFERSIZE is a macro computed from sizeof and is thus
not known at pre-processing time, so this does not work.
Since Lua 5.1 is no longer supported, we can use luaL_prepbuffsize()
which is available from Lua 5.2
Removes assumption that LUAL_BUFFERSIZE is known at pre-processing time,
which it is not in Lua 5.3 and 5.4, where it is a computed macro based
on sizeof.
Allocation of stack space is safer and faster, no need to worry about
luaL_prepbuffer failing to allocate memory and skipping free()
