CURLOPT_SSLCERT_BLOB(3) Library Functions Manual CURLOPT_SSLCERT_BLOB(3)
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 Schannel. The
format must be "P12" or "PEM" on OpenSSL. The format must be "DER" or
"PEM" on mbedTLS. The format must be "PEM" on Rustls. The format must be
specified with CURLOPT_SSLCERTTYPE(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_SSLCERT(3) 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,
Schannel, mbedTLS and wolfSSL
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 result;
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");
result = curl_easy_perform(curl);
curl_easy_cleanup(curl);
}
}
AVAILABILITY
Added in curl 7.71.0
RETURN VALUE
curl_easy_setopt(3) returns a CURLcode indicating success or error.
CURLE_OK (0) means everything was OK, non-zero means an error occurred,
see libcurl-errors(3).
SEE ALSO
CURLOPT_KEYPASSWD(3), CURLOPT_SSLCERTTYPE(3), CURLOPT_SSLKEY(3)
libcurl 2026-10-18 CURLOPT_SSLCERT_BLOB(3)
curl 8.23.0 - Generated Sun Oct 18 18:32:07 CDT 2026