---
name: "CURLOPT_SSLCERT_BLOB"
section: "3"
platform: "macos"
package: "curl"
version: "166.0.0.0.1"
release: "macOS 26.5"
platforms: ["linux", "macos"]
url: "https://new.carta.tech/CURLOPT_SSLCERT_BLOB"
---

# CURLOPT\_SSLCERT\_BLOB(3)

SSL client certificate from memory blob

## NAME

CURLOPT\_SSLCERT\_BLOB - SSL client certificate from memory blob

## SYNOPSIS

```
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSLCERT_BLOB,
                          struct curl_blob *stblob);
```

## DESCRIPTION

Pass a pointer to a curl\_blob structure, which contains (pointer and size) a client certificate. The format must be "P12" on Secure Transport or Schannel. The format must be "P12" or "PEM" on OpenSSL. The format must be "DER" or "PEM" on mbedTLS. The format must be specified with *[CURLOPT\_SSLCERTTYPE(3)](/CURLOPT_SSLCERTTYPE/3.md)*.

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\_SSLCERT(3)](/CURLOPT_SSLCERT/3.md)* which instead expects a filename as input.

## DEFAULT

NULL

## PROTOCOLS

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

## EXAMPLE

```
extern char *certificateData; /* point to data */
extern size_t filesize; /* size of data */
int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode res;
    struct curl_blob stblob;
    stblob.data = certificateData;
    stblob.len = filesize;
    stblob.flags = CURL_BLOB_COPY;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
    curl_easy_setopt(curl, CURLOPT_SSLCERT_BLOB, &stblob);
    curl_easy_setopt(curl, CURLOPT_SSLCERTTYPE, "P12");
    curl_easy_setopt(curl, CURLOPT_KEYPASSWD, "s3cret");
    res = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}
```

## AVAILABILITY

Added in 7.71.0. This option is supported by the OpenSSL, Secure Transport, Schannel and mbedTLS (since 7.78.0) 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.

## SEE ALSO

[**CURLOPT\_KEYPASSWD**(3)](/CURLOPT_KEYPASSWD/3.md), [**CURLOPT\_SSLCERTTYPE**(3)](/CURLOPT_SSLCERTTYPE/3.md), [**CURLOPT\_SSLKEY**(3)](/CURLOPT_SSLKEY/3.md)