CURLOPT_SSLCERT_BLOB - SSL client certificate from memory blob

Added in curl 7.71.0

NULL

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). 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.

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); } }

CURLOPT_SSLCERT_BLOB - SSL client certificate from memory blob

This functionality affects all TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc. This option works only with the following TLS backends: OpenSSL, Schannel, Secure Transport, mbedTLS and wolfSSL

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).

CURLOPT_KEYPASSWD(3), CURLOPT_SSLCERTTYPE(3), CURLOPT_SSLKEY(3) libcurl 2025-06-16 CURLOPT_SSLCERT_BLOB(3)

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