---
name: "CURLOPT_CAINFO_BLOB"
section: "3"
platform: "linux"
package: "curl"
version: "8.23.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux", "macos"]
url: "https://new.carta.tech/CURLOPT_CAINFO_BLOB"
---

# CURLOPT\_CAINFO\_BLOB(3)

Certificate Authority (CA) bundle in PEM format

## 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)](/CURLOPT_SSL_VERIFYPEER/3.md)* is zero and you avoid verifying the server's certificate, *[CURLOPT\_CAINFO\_BLOB(3)](/CURLOPT_CAINFO_BLOB/3.md)* is not needed.

This option overrides *[CURLOPT\_CAINFO(3)](/CURLOPT_CAINFO/3.md)*.

## 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: GnuTLS, OpenSSL, Rustls, Schannel, mbedTLS and wolfSSL

## EXAMPLE

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

## HISTORY

This option is supported by the mbedTLS (since 7.81.0), Rustls (since 7.82.0), wolfSSL (since 8.2.0), GnuTLS (since 8.18.0), OpenSSL and Schannel backends.

## AVAILABILITY

Added in curl 7.77.0

## RETURN VALUE

*[curl\_easy\_setopt(3)](/curl_easy_setopt/3.md)* returns a CURLcode indicating success or error.

CURLE\_OK (0) means everything was OK, non-zero means an error occurred, see *[libcurl-errors(3)](/libcurl-errors/3.md)*.

## SEE ALSO

[**CURLOPT\_CAINFO**(3)](/CURLOPT_CAINFO/3.md), [**CURLOPT\_CAPATH**(3)](/CURLOPT_CAPATH/3.md), [**CURLOPT\_SSL\_VERIFYHOST**(3)](/CURLOPT_SSL_VERIFYHOST/3.md), [**CURLOPT\_SSL\_VERIFYPEER**(3)](/CURLOPT_SSL_VERIFYPEER/3.md)