---
name: "CURLOPT_PROXY_SSLCERT_BLOB"
section: "3"
platform: "linux"
package: "curl"
version: "8.23.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux", "macos"]
url: "https://new.carta.tech/CURLOPT_PROXY_SSLCERT_BLOB"
---

# CURLOPT\_PROXY\_SSLCERT\_BLOB(3)

SSL proxy client certificate from memory blob

## NAME

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

## SYNOPSIS

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

## DESCRIPTION

Pass a pointer to a curl\_blob structure, which contains information (pointer and size) about a memory block with binary data of the certificate used to connect to the HTTPS proxy. The format must be "P12" on Schannel. The format must be "P12" or "PEM" on OpenSSL. The format must be "PEM" on Rustls. The string "P12" or "PEM" must be specified with *[CURLOPT\_PROXY\_SSLCERTTYPE(3)](/CURLOPT_PROXY_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\_PROXY\_SSLCERT(3)](/CURLOPT_PROXY_SSLCERT/3.md)* which instead expects a filename as input.

## DEFAULT

NULL

## PROTOCOLS

This functionality affects  all TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc. only

This option works only with the following TLS backends: OpenSSL, Rustls and Schannel

## EXAMPLE

```
extern char *certificateData; /* point to data */
extern size_t filesize; /* size of the data */
int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode result;
    struct curl_blob blob;
    blob.data = certificateData;
    blob.len = filesize;
    blob.flags = CURL_BLOB_COPY;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
    curl_easy_setopt(curl, CURLOPT_PROXY, "https://proxy.example");
    curl_easy_setopt(curl, CURLOPT_PROXY_SSLKEY, "key.pem");
    curl_easy_setopt(curl, CURLOPT_PROXY_KEYPASSWD, "s3cret");
    curl_easy_setopt(curl, CURLOPT_PROXY_SSLCERT_BLOB, &blob);
    result = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}
```

## AVAILABILITY

Added in curl 7.71.0

## RETURN VALUE

*[curl\_easy\_setopt(3)](/curl_easy_setopt/3.md)* returns a CURLcode indicating success or error.

CURLE\_OK (0) means everything was OK, non-zero means an error occurred, see *[libcurl-errors(3)](/libcurl-errors/3.md)*.

## SEE ALSO

[**CURLOPT\_PROXY\_SSLCERT**(3)](/CURLOPT_PROXY_SSLCERT/3.md), [**CURLOPT\_PROXY\_SSLCERTTYPE**(3)](/CURLOPT_PROXY_SSLCERTTYPE/3.md), [**CURLOPT\_PROXY\_SSLKEY**(3)](/CURLOPT_PROXY_SSLKEY/3.md), [**CURLOPT\_SSLCERT\_BLOB**(3)](/CURLOPT_SSLCERT_BLOB/3.md)