curl / libcurl / API / curl_easy_setopt / CURLOPT_HTTPSIG_HEADERS

CURLOPT_HTTPSIG_HEADERS explained

Name

CURLOPT_HTTPSIG_HEADERS - components to sign for HTTP Message Signatures

Synopsis

#include <curl/curl.h>
 
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HTTPSIG_HEADERS,
                          char *components);

Description

This feature is experimental and may change before it is considered stable. We advise against using it in production.

Pass a space-separated list of component identifiers to include in the RFC 9421 HTTP Message Signature.

Derived components are given as bare names:

- method - the HTTP method (GET, POST, etc.) - authority - the host and optional port - path - the request path - query - the query string including the leading ?

HTTP header fields are given with a trailing colon, for example content-type: or content-digest:. This mirrors how a header looks and keeps a leading @ free for its usual curl meaning (read the value from a file).

If this option is not set, the default components are method, authority, path (plus query when a query string is present).

Signing request headers

Header components are resolved from the list set with CURLOPT_HTTPHEADER only. Headers that libcurl adds later (such as the default User-Agent) are not visible to the signer unless the application supplies them explicitly.

To sign User-Agent, supply it via CURLOPT_HTTPHEADER together with this option before the transfer; see EXAMPLE.

Each component identifier may appear at most once (RFC 9421 Section 2). Listing the same component twice returns CURLE_BAD_FUNCTION_ARGUMENT.

At most 16 components are accepted; supplying more returns CURLE_BAD_FUNCTION_ARGUMENT.

The application does not have to keep the string around after setting this option.

Default

NULL (uses the default component set)

Protocols

This functionality affects http only

Example

int main(void)
{
  CURL *curl = curl_easy_init();
  struct curl_slist *headers = NULL;
 
  if(curl) {
    headers = curl_slist_append(headers, "User-Agent: MyApp/1.0");
    curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
    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_setopt(curl, CURLOPT_HTTPSIG_HEADERS,
                     "method authority path content-type: user-agent:");
    curl_easy_perform(curl);
    curl_slist_free_all(headers);
  }
}

Availability

Added in curl 8.22.0

Return value

curl_easy_setopt returns a CURLcode indicating success or error.

CURLE_OK (0) means everything was OK, non-zero means an error occurred, see libcurl-errors.