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/* What an epoch's X25519 costs here (docs/research/099-link-epochs.md): a
* pair made, a raw private half taken in (OpenSSL works out its public half
* again), and the secret with a peer's public key.
*
* cc -O2 x25519.c -lcrypto -o x25519 && ./x25519 */
#include <openssl/evp.h>
#include <stdio.h>
#include <time.h>
static double now(void) {
struct timespec t;
clock_gettime(CLOCK_MONOTONIC, &t);
return (double)t.tv_sec + (double)t.tv_nsec / 1e9;
}
int main(void) {
enum { N = 2000 };
unsigned char private_key[32], peer[32], out[32];
size_t length = 32;
EVP_PKEY *other = EVP_PKEY_Q_keygen(NULL, NULL, "X25519"), *mine = NULL;
EVP_PKEY_get_raw_public_key(other, peer, &length);
double t = now();
for (int i = 0; i < N; ++i) {
EVP_PKEY *k = EVP_PKEY_Q_keygen(NULL, NULL, "X25519");
length = 32;
EVP_PKEY_get_raw_private_key(k, private_key, &length);
EVP_PKEY_free(k);
}
printf("{\"pair_us\":%.1f,", (now() - t) / N * 1e6);
t = now();
for (int i = 0; i < N; ++i) EVP_PKEY_free(EVP_PKEY_new_raw_private_key(EVP_PKEY_X25519, NULL, private_key, 32));
printf("\"private_in_us\":%.1f,", (now() - t) / N * 1e6);
mine = EVP_PKEY_new_raw_private_key(EVP_PKEY_X25519, NULL, private_key, 32);
EVP_PKEY *theirs = EVP_PKEY_new_raw_public_key(EVP_PKEY_X25519, NULL, peer, 32);
EVP_PKEY_CTX *context = EVP_PKEY_CTX_new(mine, NULL);
EVP_PKEY_derive_init(context);
EVP_PKEY_derive_set_peer(context, theirs);
t = now();
for (int i = 0; i < N; ++i) {
length = 32;
EVP_PKEY_derive(context, out, &length);
}
printf("\"secret_us\":%.1f,\"openssl\":\"%s\"}\n", (now() - t) / N * 1e6, OpenSSL_version(OPENSSL_VERSION));
EVP_PKEY_CTX_free(context);
EVP_PKEY_free(theirs);
EVP_PKEY_free(mine);
EVP_PKEY_free(other);
return 0;
}
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