CURLOPT_CAINFO_BLOB - Certificate Authority (CA) bundle in PEM format

Added in curl 7.77.0

NULL

Pass a pointer to a curl_blob structure, which contains information (pointer and size) about a memory block with binary data of PEM encoded content holding one or more certificates to verify the HTTPS server with. 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. If CURLOPT_SSL_VERIFYPEER(3) is zero and you avoid verifying the server's certificate, CURLOPT_CAINFO_BLOB(3) is not needed. This option overrides CURLOPT_CAINFO(3).

#include <string.h> int main(void) { char *strpem = "PEMDATA"; /* strpem must point to a PEM string */ CURL *curl = curl_easy_init(); if(curl) { CURLcode res; struct curl_blob blob; curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/"); blob.data = strpem; blob.len = strlen(strpem); blob.flags = CURL_BLOB_COPY; curl_easy_setopt(curl, CURLOPT_CAINFO_BLOB, &blob); res = curl_easy_perform(curl); curl_easy_cleanup(curl); } }

This option is supported by the BearSSL (since 7.79.0), mbedTLS (since 7.81.0), Rustls (since 7.82.0), wolfSSL (since 8.2.0), OpenSSL, Secure Transport and Schannel backends.

CURLOPT_CAINFO_BLOB - Certificate Authority (CA) bundle in PEM format

This functionality affects all TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc. This option works only with the following TLS backends: BearSSL, OpenSSL, Schannel, Secure Transport, mbedTLS, rustls 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_CAINFO(3), CURLOPT_CAPATH(3), CURLOPT_SSL_VERIFYHOST(3), CURLOPT_SSL_VERIFYPEER(3) libcurl 2025-06-16 CURLOPT_CAINFO_BLOB(3)

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