CURLOPT_HTTPSIG_KEYID(3) Library Functions Manual CURLOPT_HTTPSIG_KEYID(3)
NAME
CURLOPT_HTTPSIG_KEYID - key identifier for HTTP Message Signatures
SYNOPSIS
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HTTPSIG_KEYID, char *keyid);
DESCRIPTION
This feature is experimental and may change before it is considered
stable. We advise against using it in production.
Pass a null-terminated string that identifies the key used for RFC 9421
HTTP Message Signatures. This value is included as the keyid parameter
in the Signature-Input header, allowing the server to look up the
corresponding verification key.
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.
DEFAULT
NULL
PROTOCOLS
This functionality affects http only
EXAMPLE
int main(void)
{
CURL *curl = curl_easy_init();
if(curl) {
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/api");
curl_easy_setopt(curl, CURLOPT_HTTPSIG_ALGORITHM, CURLHTTPSIG_ED25519);
curl_easy_setopt(curl, CURLOPT_HTTPSIG_KEY,
"9f8362f87a484a954e6e740c5b4c0e84"
"229139a20aa8ab56ff66586f6a7d29c5");
curl_easy_setopt(curl, CURLOPT_HTTPSIG_KEYID, "my-key-id");
curl_easy_perform(curl);
}
}
AVAILABILITY
Added in curl 8.22.0
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_HTTPSIG_ALGORITHM(3), CURLOPT_HTTPSIG_KEY(3)
libcurl 2026-09-03 CURLOPT_HTTPSIG_KEYID(3)
curl 8.22.0 - Generated Sun Sep 6 12:47:17 CDT 2026