Unicode C
Unicode C
Implementing DPoP with OAuth2 Client Credentials
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Demonstrating Proof-of-Possession (DPoP) is an OAuth 2.0 extension (RFC 9449) that secures access tokens by binding them to a specific client’s private key, preventing stolen token misuse. It requires the client to sign a JWT (DPoP Proof) with every request, proving they hold the private key.This example shows how to use Chilkat v11.4.0 or later to automatically add the following headers to HTTP requests:
Authorization: DPoP <access_token> DPoP: <new JWT signed with same key>
Chilkat Unicode C Downloads
#include <C_CkPrivateKeyW.h>
#include <C_CkJsonObjectW.h>
#include <C_CkHttpW.h>
void ChilkatSample(void)
{
BOOL success;
HCkPrivateKeyW privKey;
const wchar_t *tokenEndpoint;
const wchar_t *apiEndpoint;
HCkJsonObjectW json;
HCkHttpW http;
const wchar_t *resp;
int statusCode;
success = FALSE;
privKey = CkPrivateKeyW_Create();
// Load your ECDSA private key. (Keys uses with DPoP must always be ECDSA keys. Not RSA.)
success = CkPrivateKeyW_LoadAnyFormatFile(privKey,L"qa_data/pem/ecc_privKey.pem",L"");
if (success == FALSE) {
wprintf(L"%s\n",CkPrivateKeyW_lastErrorText(privKey));
CkPrivateKeyW_Dispose(privKey);
return;
}
tokenEndpoint = L"https://demo.duendesoftware.com/connect/token";
apiEndpoint = L"https://demo.duendesoftware.com/api/dpop/test";
// Provide the details needed for Chilkat to automatically fetch the access token
// using the client_credentials OAuth2 flow.
json = CkJsonObjectW_Create();
CkJsonObjectW_UpdateString(json,L"client_secret",L"secret");
CkJsonObjectW_UpdateString(json,L"client_id",L"m2m.dpop");
CkJsonObjectW_UpdateString(json,L"token_endpoint",tokenEndpoint);
CkJsonObjectW_UpdateString(json,L"scope",L"api");
http = CkHttpW_Create();
CkHttpW_putSessionLogFilename(http,L"c:/aaworkarea/sessionLog.txt");
// Provide private key to be used with DPoP
success = CkHttpW_SetDPoPKey(http,privKey);
if (success == FALSE) {
wprintf(L"%s\n",CkHttpW_lastErrorText(http));
CkPrivateKeyW_Dispose(privKey);
CkJsonObjectW_Dispose(json);
CkHttpW_Dispose(http);
return;
}
CkHttpW_putAuthToken(http,CkJsonObjectW_emit(json));
// When we make the first request to an API endpoint, we don't yet have
// an OAuth2 access token. Chilkat (internally) will use the token endpoint
// to automatically get an access token.
// Chilkat will then add the following headers to the request sent to the API endpoint:
// Authorization: DPoP <access_token>
// DPoP: <new JWT signed with same key>
// For subsequent requests using the same Chilkat HTTP object instance,
// the same access token will be used with a newly generated DPoP header for each request.
// When the access_token is expired or about to expire, Chilkat will automatically (internally)
// refresh the access token. Your application does not need to be concerned with the
// complexities of fetching the access token or managing the refresh, or generating
// the DPoP header for each request.
resp = CkHttpW_quickGetStr(http,apiEndpoint);
if (CkHttpW_getLastMethodSuccess(http) == FALSE) {
wprintf(L"%s\n",CkHttpW_lastErrorText(http));
CkPrivateKeyW_Dispose(privKey);
CkJsonObjectW_Dispose(json);
CkHttpW_Dispose(http);
return;
}
statusCode = CkHttpW_getLastStatus(http);
wprintf(L"response status code = %d\n",statusCode);
wprintf(L"%s\n",resp);
// Here is a Session log showing the raw HTTP request(s) and response(s).
// Notice how Chilkat automatically fetched the access_token and then used it in the API request.
// ---- Sending Mon, 30 Mar 2026 20:09:44 GMT ----
// POST /connect/token HTTP/1.1
// Host: demo.duendesoftware.com
// Content-Type: application/x-www-form-urlencoded
// Content-Length: 79
// DPoP: ****
//
// client_secret=secret&client_id=m2m.dpop&scope=api&grant_type=client_credentials
// ---- Received Mon, 30 Mar 2026 20:09:44 GMT ----
// HTTP/1.1 200 OK
// Date: Mon, 30 Mar 2026 20:09:43 GMT
// Content-Type: application/json; charset=UTF-8
// Transfer-Encoding: chunked
// Connection: keep-alive
// Server: Kestrel
// Cache-Control: no-store, no-cache, max-age=0
// Pragma: no-cache
// X-REVISION: 4f42f7e7
//
// 374
// {"access_token":"eyJhbGciOiJSUzI1NiIsImtpZCI6IjE1OEUyRDQ1NzhFNDMyOUJBMzRGNzkxQTQ4Nzk5NzYwIiwieDV0IjoiczkyM2RnYnhWbnhoaTJSZmR1cWZyZXZIYUUwIi
// widHlwIjoiYXQrand0In0.eyJpc3MiOiJodHRwczovL2RlbW8uZHVlbmRlc29mdHdhcmUuY29tIiwibmJmIjoxNzc0OTAxMzgzLCJpYXQiOjE3NzQ5MDEzODMsImV4cCI6MTc3NDkwN
// Dk4MywiYXVkIjoiYXBpIiwiY25mIjp7ImprdCI6IlVMR2J4ZXdNOEZUNDhTd3hKeUY3YnJuMDZWMDdPZ3VpdW41d1ZzSVVENEUifSwic2NvcGUiOlsiYXBpIl0sImNsaWVudF9pZCI6
// Im0ybS5kcG9wIiwianRpIjoiQ0Q5MjBFQzQyOTRBOTA3QUUyRjMyQjlCREQzQTA3QzMifQ.bbq8tNMVtJp79Wc9xrAsE0h8oOfdxEKtGZ3qHpJX-mvSS4FVXLoO2bfpq1nhFryfbZkk
// ENfoIwSQjb_35aziq2NrnpWwQ4vDF1b9K-b7eJXPmJybm61DAP9HSE3ZI0jMrMTRFLtjwvE4WV6ZXNTwN0Pzn6teog1i09PZQkaGtlJEBjsBaN5N7OsQvtgFLD0sNkjy1JTw5LMNE7u
// 5-W32qv-XDk9KEGfoBkqyt-SR_A2wI7oZvl4OGnYyX8tUOFszlHZKy0_0V3Oc9wkHRM2JZDA_LfTqldJHR5CF5FuNiJ2hp-kioUA-i0gWxhqnVKVspJqQAN3Z95RDl9jSf-pYSg",
// "expires_in":3600,"token_type":"DPoP","scope":"api"}
// 0
//
//
// ---- Sending Mon, 30 Mar 2026 20:09:44 GMT ----
// GET /api/dpop/test HTTP/1.1
// Host: demo.duendesoftware.com
// Accept: */*
// Accept-Encoding: gzip
// Authorization: ****
// DPoP: ****
//
//
// ---- Received Mon, 30 Mar 2026 20:09:44 GMT ----
// HTTP/1.1 200 OK
// Date: Mon, 30 Mar 2026 20:09:44 GMT
// Content-Type: application/json; charset=utf-8
// Transfer-Encoding: chunked
// Connection: keep-alive
// Server: Kestrel
// X-REVISION: 4f42f7e7
//
// 420
// [{"type":"iss","value":"https://demo.duendesoftware.com"},{"type":"nbf","value":"1774901383"},{"type":"iat","value":"1774901383"},
// {"type":"exp","value":"1774904983"},{"type":"aud","value":"api"},{"type":"cnf","value":"{\u0022jkt\u0022:\u0022ULGbxewM8FT48SwxJyF7brn06V07Oguiun5wVsIUD4E\u0022}"},
// {"type":"scope","value":"api"},{"type":"client_id","value":"m2m.dpop"},{"type":"jti","value":"CD920EC4294A907AE2F32B9BDD3A07C3"},
// {"type":"authorization_scheme","value":"DPoP"},{"type":"proof_token","value":"eyJhbGciOiJFU .... aGrGOgkRXLQ"}]
// 0
//
//
CkPrivateKeyW_Dispose(privKey);
CkJsonObjectW_Dispose(json);
CkHttpW_Dispose(http);
}