---
c: Copyright (C) Daniel Stenberg, <daniel.se>, et al.
SPDX-License-Identifier: curl
Title: CURLOPT_SSLKEY_BLOB
Section: 3
Source: libcurl
See-also:
  - CURLOPT_SSLKEY (3)
  - CURLOPT_SSLKEYTYPE (3)
---

# NAME

CURLOPT_SSLKEY_BLOB - private key for client cert from memory blob

# SYNOPSIS

~~~c
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSLKEY_BLOB,
                          struct curl_blob *blob);
~~~

# DESCRIPTION

Pass a pointer to a curl_blob structure, which contains information (pointer
and size) for a private key. Compatible with OpenSSL. The format (like "PEM")
must be specified with CURLOPT_SSLKEYTYPE(3).

If the blob is initialized with the flags member of struct curl_blob set to
CURL_BLOB_COPY, the application does not have to keep the buffer around after
setting this.

This option is an alternative to CURLOPT_SSLKEY(3) which instead expects a
filename as input.

# DEFAULT

NULL

# PROTOCOLS

All TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.

# EXAMPLE

~~~c

extern char *certificateData; /* point to cert */
extern size_t filesize; /* size of cert */

extern char *privateKeyData; /* point to key */
extern size_t privateKeySize; /* size of key */

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode res;
    struct curl_blob blob;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
    blob.data = certificateData;
    blob.len = filesize;
    blob.flags = CURL_BLOB_COPY;
    curl_easy_setopt(curl, CURLOPT_SSLCERT_BLOB, &blob);
    curl_easy_setopt(curl, CURLOPT_SSLCERTTYPE, "PEM");

    blob.data = privateKeyData;
    blob.len = privateKeySize;
    curl_easy_setopt(curl, CURLOPT_SSLKEY_BLOB, &blob);
    curl_easy_setopt(curl, CURLOPT_KEYPASSWD, "s3cret");
    curl_easy_setopt(curl, CURLOPT_SSLKEYTYPE, "PEM");
    res = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}
~~~

# AVAILABILITY

Added in 7.71.0. This option is supported by the OpenSSL backends.

# RETURN VALUE

Returns CURLE_OK if TLS enabled, CURLE_UNKNOWN_OPTION if not, or
CURLE_OUT_OF_MEMORY if there was insufficient heap space.
