gistfile1.txt

#include <stdio.h>
#include <fcntl.h>
#include <openssl/pem.h>

int main(int argc, char ** argv) {
  BIO * bio_pubkey = NULL;
  EVP_PKEY * evp_pubkey = NULL;
  RSA * rsa = NULL;

  int fd = open("public.pem", O_RDONLY);
  if (fd == -1) {
    perror("open public.pem");
    exit(-1);
  }

  char pubkey_pem[16 * 1024];
  int totalread = 0, numread;

  while ((numread = read(fd, pubkey_pem + totalread, sizeof(pubkey_pem) - totalread - 1)) > 0) {
    totalread += numread;
  }
  close(fd);

  pubkey_pem[totalread] = '\0';

  printf("pubkey_pem =\n%s\n", pubkey_pem);

  bio_pubkey = BIO_new_mem_buf(pubkey_pem, -1);
  printf("bio_pubkey = %p\n", bio_pubkey);

  rsa = PEM_read_bio_RSAPublicKey(bio_pubkey, NULL, NULL, NULL);
  printf("rsa = %p\n", rsa);
}