How to convert HEX to PEM openssl c++

Question

I am trying to convert a hex string to pem format using openssl, I can do it using the openssl command but would like to do in c++ rather then rely on breaking out to the console

Example Hex String:

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

I am writing the above to a file and then converting using xxd and openssl to pem formated cert

cat example.txt | xxd -r -p | openssl x509 -inform der -out example.cert which produces something like. Truncated to reduce size of the post.

How can I do this in c++ using openssl?

I have also tried from Convert a plain public key to PEM

#include <stdio.h>
#include <stdlib.h>
#include <openssl/ec.h>
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/objects.h>
#include <openssl/pem.h>
#ifdef _WIN32
#include <openssl/applink.c>
#endif

void err (const char *label){  // for test; improve for real code
  fprintf (stderr, "Error in %s:\n", label);
  ERR_print_errors_fp (stderr);
  exit (1);
}

int main (void) //(int argc, char**argv)
{
  ERR_load_crypto_strings(); /* or SSL_load_error_strings */
  //OPENSSL_add_all_algorithms_noconf(); /* for PKCS#8 */

  // test data -- replace for real use
  char hex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
  unsigned char raw [65]; for( int i = 0; i < 65; i++ ){ sscanf(hex+2*i, "%2hhx", raw+i); }

  EC_KEY *eck = EC_KEY_new_by_curve_name(NID_X9_62_prime256v1); /* or OBJ_txt2nid("prime256v1") */
  if( !eck ) err("ECCnewbyname");
  EC_KEY_set_asn1_flag(eck, OPENSSL_EC_NAMED_CURVE); /* needed below 1.1.0 */
  const unsigned char *ptr = raw;
  if( !o2i_ECPublicKey (&eck, &ptr, sizeof(raw)) ) err("o2iECPublic=point");
  EVP_PKEY * pkey = EVP_PKEY_new();
  if( !EVP_PKEY_assign_EC_KEY(pkey, eck) ) err("PKEYassign");

  BIO *bio = BIO_new(BIO_s_mem());
  if( !PEM_write_bio_PUBKEY (bio, pkey) ) err("PEMwrite");
  char *pem = NULL; long len = BIO_get_mem_data (bio, &pem);
  fwrite (pem, 1, len, stdout); // for test; for real use as needed
  return 0;
}

But I get

Error in o2iECPublic=point:
40B790FB647F0000:error:08000066:elliptic curve routines:ossl_ec_GFp_simple_oct2point:invalid encoding:../crypto/ec/ecp_oct.c:295:
40B790FB647F0000:error:08080010:elliptic curve routines:o2i_ECPublicKey:EC lib:../crypto/ec/ec_asn1.c:1142:

What am I doing wrong?

How to convert HEX to PEM openssl c++

0 Answers0