CURLOPT_CAINFO_BLOB(3) Library Functions Manual CURLOPT_CAINFO_BLOB(3)
NAME
CURLOPT_CAINFO_BLOB - Certificate Authority (CA) bundle in PEM format
SYNOPSIS
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_CAINFO_BLOB,
struct curl_blob *stblob);
DESCRIPTION
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).
DEFAULT
NULL
PROTOCOLS
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
EXAMPLE
#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);
}
}
HISTORY
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.
AVAILABILITY
Added in curl 7.77.0
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_CAINFO(3), CURLOPT_CAPATH(3), CURLOPT_SSL_VERIFYHOST(3), CUR-
LOPT_SSL_VERIFYPEER(3)
libcurl 2026-07-12 CURLOPT_CAINFO_BLOB(3)
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