#include <linux/if_alg.h>
#include <linux/rtnetlink.h>
#include <sys/socket.h>

int main() {
  int fd;
  struct sockaddr_alg addr = {
    .salg_type = "aead",
    .salg_name = "authenc(hmac(sha256),cbc(aes))",
  };

  struct {
      struct rtattr attr;
      __be32 enckeylen;
      char keys[1];
  } __attribute__((packed)) key = {
    .attr.rta_len = sizeof(key),
    .attr.rta_type = 1 /* CRYPTO_AUTHENC_KEYA_PARAM */,
  };

  fd = socket(AF_ALG, SOCK_SEQPACKET, 0);
  bind(fd, (void *)&addr, sizeof(addr));
  setsockopt(fd, SOL_ALG, ALG_SET_KEY, &key, sizeof(key));
}