Re: how to extract the private key out of the KEY.PEM

[sampo]

"Dave Thompson" <dthomp...@prinpay.com> said:
> privatekeys - man PEM -- but the PEM_read routines can handle 

This is how I do it...

#define PEM_CERT_START          "-----BEGIN CERTIFICATE-----"
#define PEM_CERT_END              "-----END CERTIFICATE-----"
#define PEM_RSA_PRIV_KEY_START  "-----BEGIN RSA PRIVATE KEY-----"
#define PEM_RSA_PRIV_KEY_END      "-----END RSA PRIVATE KEY-----"
#define PEM_DSA_PRIV_KEY_START  "-----BEGIN DSA PRIVATE KEY-----"
#define PEM_DSA_PRIV_KEY_END      "-----END DSA PRIVATE KEY-----"
#define PEM_PRIV_KEY_START      "-----BEGIN PRIVATE KEY-----"

EVP_PKEY* zxid_extract_private_key(char* buf)
{
  char* p;
  char* e;
  int typ;
  EVP_PKEY* pk = 0;  /* Forces d2i_PrivateKey() to alloc the memory. */
  OpenSSL_add_all_algorithms();
  
  if (p = strstr(buf, PEM_RSA_PRIV_KEY_START)) {
    typ = EVP_PKEY_RSA;
    e = PEM_RSA_PRIV_KEY_END;
    p += sizeof(PEM_RSA_PRIV_KEY_START) - 1;
  } else if (p = strstr(buf, PEM_DSA_PRIV_KEY_START)) {
    typ = EVP_PKEY_DSA;
    e = PEM_DSA_PRIV_KEY_END;
    p += sizeof(PEM_DSA_PRIV_KEY_START) - 1;
  } else if (p = strstr(buf, PEM_PRIV_KEY_START)) {  /* Not official format, 
but sometimes seen. */
    typ = EVP_PKEY_RSA;
    e = PEM_PRIV_KEY_END;
    p += sizeof(PEM_PRIV_KEY_START) - 1;
  } else {
    ERR("No private key found in buf. Looking for separator (%s) or (%s).\npem 
data(%s)", PEM_RSA_PRIV_KEY_START, PEM_DSA_PRIV_KEY_START, buf);
    return 0;
  }
  if (*p == 0xd) ++p;
  if (*p != 0xa) {
    ERR("Bad privkey missing newline ch(0x%x) at %ld (%.*s) of buf(%s)", *p, 
(long)(p-buf), 5, p-2, buf);
    return 0;
  }
  ++p;

  e = strstr(buf, e);
  if (!e) {
    ERR("End marker not found, typ=%d", typ);
    return 0;
  }
  
  p = unbase64_raw(p, e, buf, zx_std_index_64);
  if (!d2i_PrivateKey(typ, &pk, (const unsigned char**)&buf, p-buf) || !pk) {
    zx_report_openssl_err("extract_private_key");
    ERR("DER decoding of private key failed.\n%d", 0);
    return 0;
  }
  zx_report_openssl_err("extract_private_key2");
  return pk; /* RSA* rsa = EVP_PKEY_get1_RSA(pk); */
}

Cheers,
--Sampo
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