CURLOPT_CAINFO(3) Library Functions Manual CURLOPT_CAINFO(3)
NAME
CURLOPT_CAINFO - path to Certificate Authority (CA) bundle
SYNOPSIS
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_CAINFO, char *path);
DESCRIPTION
Pass a char pointer to a null-terminated string naming a file holding
one or more certificates to verify the peer with.
If CURLOPT_SSL_VERIFYPEER(3) is zero and you avoid verifying the
server's certificate, CURLOPT_CAINFO(3) need not even indicate an acces-
sible file.
This option is by default set to the system path where libcurl's CA cer-
tificate bundle is assumed to be stored, as established at build time.
(iOS and macOS) When curl uses Secure Transport this option is sup-
ported. If the option is not set, then curl uses the certificates in the
system and user Keychain to verify the peer.
(Schannel) This option is supported for Schannel in Windows 7 or later
but we recommend not using it until Windows 8 since it works better
starting then. If the option is not set, then curl uses the certifi-
cates in the Windows' store of root certificates (the default for Schan-
nel).
The application does not have to keep the string around after setting
this option.
Using this option multiple times makes the last set string override the
previous ones. Set it to NULL to disable its use again.
The default value for this can be figured out with CURLINFO_CAINFO(3).
DEFAULT
Built-in system specific. When curl is built with Secure Transport or
Schannel, this option is not set by default.
PROTOCOLS
This functionality affects all TLS based protocols: HTTPS, FTPS, IMAPS,
POP3S, SMTPS etc.
All TLS backends support this option.
EXAMPLE
int main(void)
{
CURL *curl = curl_easy_init();
if(curl) {
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
curl_easy_setopt(curl, CURLOPT_CAINFO, "/etc/certs/cabundle.pem");
curl_easy_perform(curl);
curl_easy_cleanup(curl);
}
}
HISTORY
Schannel support added in libcurl 7.60.
AVAILABILITY
Added in curl 7.4.2
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
CURLINFO_CAINFO(3), CURLOPT_CAINFO_BLOB(3), CURLOPT_CAPATH(3), CUR-
LOPT_CA_CACHE_TIMEOUT(3), CURLOPT_SSL_VERIFYHOST(3), CURLOPT_SSL_VERI-
FYPEER(3)
libcurl 2026-07-12 CURLOPT_CAINFO(3)
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