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AuthForge C++ SDK

Official C++ SDK for AuthForge: credit-based license key authentication with Ed25519-verified responses.

Single-source CMake library. Public headers plus one implementation file (authforge_sdk.cpp) packaged as authforge_sdk, linking libsodium (Ed25519), OpenSSL (SHA and helpers), and libcurl (HTTP). Targets C++17. Works on Windows (MSVC), Linux (GCC/Clang), and macOS (Clang).

How licensing works

  1. Activate: the SDK validates the license key online via POST /auth/validate. The server checks revocation, expiry, HWID binding, and credits, then returns an Ed25519-signed session with a TTL.
  2. Grace period: by default the app keeps running on that signed session without contacting AuthForge for the length of the session TTL (default 24h, server clamps 1h to 7d). A background loop re-verifies the signed session locally and fails when the grace period ends.
  3. Online check-ins (optional): opt in with authforge::OnlineHeartbeat::On to have the SDK call POST /auth/heartbeat every heartbeatInterval seconds for fast revocation and concurrent-use detection.

Features

Everything in this list ships in authforge_sdk.h / authforge_sdk.cpp today:

  • License activation via POST /auth/validate, returning a signed ValidateLicenseResult.
  • Ed25519 signature verification (libsodium) on every /auth/validate and /auth/heartbeat response; tampered or unsigned responses are rejected.
  • Key rotation: a single-key constructor (also accepts a comma-separated string) and a std::vector<std::string> rotation-set constructor. The SDK trusts a signature that matches any key, so you can roll the server-side signing key without breaking deployed clients.
  • Nonce anti-replay: a fresh 128-bit nonce is sent on every request and the echoed nonce in the signed payload is checked before the response is accepted.
  • HWID fingerprinting: deterministic device hash from MAC + CPU + disk serial, with graceful per-component fallback.
  • hwidOverride: bind to any identity instead of the machine (for example tg:<id>, discord:<id>).
  • Seat enforcement: the server binds each HWID into a license's free slots up to maxHwidSlots; maxHwidSlots / hwidCount are surfaced on the validate result. A shared (unlimited-seat) key skips per-device binding.
  • Grace period by default, online check-ins on demand (see Grace period and online check-ins).
  • Offline license files (.authforge): LoginFromFile() / VerifyLicenseFile() verify a cloud-minted, Ed25519-signed file with zero network access for air-gapped machines.
  • Self-ban (SelfBan(...)) for anti-tamper response, both pre-session and post-session.
  • Grace period duration control (ttlSeconds) with server-side clamping to [3600, 604800].
  • App variables / license variables for feature flags and tiered licensing.
  • Automatic retries for rate-limited and transient network failures, with a fresh nonce per retry.

There is no C++ package registry for this SDK. Ship source via GitHub Releases (tag v*, source archive) or by cloning the repository, then build with CMake as below.

Quick Start

Add authforge_sdk.h and authforge_sdk.cpp to your project, then:

#include "authforge_sdk.h"
#include <iostream>
#include <string>

int main() {
    authforge::AuthForgeClient client(
        "YOUR_APP_ID",           // from your AuthForge dashboard
        "YOUR_APP_SECRET",       // from your AuthForge dashboard
        "YOUR_PUBLIC_KEY"        // base64 Ed25519 public key from dashboard
    );
    // Default policy: activate online once, then run through the grace
    // period (no network). Pass authforge::OnlineHeartbeat::On as the 4th
    // argument to enable online check-ins.

    std::string key;
    std::cout << "Enter license key: ";
    std::getline(std::cin, key);

    if (client.Login(key)) {
        std::cout << "Authenticated!" << std::endl;
        // Your app logic here; the background session check runs automatically
    } else {
        std::cout << "Invalid license key." << std::endl;
        return 1;
    }

    return 0;
}

Building

CMake

cmake -S . -B build
cmake --build build
cmake --install build --prefix /your/prefix

CMake must be able to find libsodium, OpenSSL, and libcurl (headers and libraries). Examples:

  • Linux (Debian/Ubuntu): sudo apt install libsodium-dev libssl-dev libcurl4-openssl-dev
  • macOS (Homebrew): brew install libsodium openssl curl. If CMake does not pick up Homebrew paths automatically, set CMAKE_PREFIX_PATH to your prefix (often /opt/homebrew on Apple Silicon, /usr/local on Intel).
  • Windows: Install dependencies with vcpkg, then configure with its toolchain file, for example:
    vcpkg install libsodium:x64-windows openssl:x64-windows curl:x64-windows
    cmake -S . -B build -DCMAKE_TOOLCHAIN_FILE=%VCPKG_ROOT%\scripts\buildsystems\vcpkg.cmake
    (Adjust triplet and VCPKG_ROOT to match your setup.)

Using from another CMake project

find_package(AuthForge CONFIG REQUIRED)
target_link_libraries(yourapp PRIVATE AuthForge::authforge_sdk)

Configuration

Parameter Type Default Description
appId string required Your application ID from the AuthForge dashboard
appSecret string required for online APIs; "" for LoginFromFile only Your application secret from the AuthForge dashboard. Do not ship it in air-gapped binaries.
publicKey std::string / std::vector<std::string> required App Ed25519 public key(s) (base64) from dashboard. The single-string overload accepts a comma-separated trust list; the std::vector<std::string> overload takes a rotation set. The SDK trusts a signature matching any key (see Key rotation).
onlineHeartbeat authforge::OnlineHeartbeat OnlineHeartbeat::Off Off (default): run through the grace period on the signed session, no network after activation. On: enable online check-ins via /auth/heartbeat (see below).
heartbeatInterval int 900 Seconds between background checks (minimum 10; default 15 min). With online check-ins enabled, this is the check-in cadence.
apiBaseUrl string https://auth.authforge.cc API endpoint
onFailure std::function nullptr Callback (const string&, const exception*) on auth failure
requestTimeout int 15 HTTP request timeout in seconds
ttlSeconds int 0 (server default: 86400) Requested grace period duration in seconds (the session token lifetime). 0 means "server default" (24h). Server clamps to [3600, 604800] (1h to 7d); preserved across heartbeat refreshes.
hwidOverride string "" Optional custom hardware/subject identifier. When non-empty, the SDK uses this value instead of generated device fingerprint data.

Identity-based binding example (Telegram/Discord)

authforge::AuthForgeClient client(
    "YOUR_APP_ID",
    "YOUR_APP_SECRET",
    "YOUR_PUBLIC_KEY",
    authforge::OnlineHeartbeat::On,
    900,
    authforge::AuthForgeClient::kDefaultApiBaseUrl,
    onFailure,
    15,
    0,
    "tg:" + std::to_string(telegramUserId) // or "discord:" + std::to_string(discordUserId)
);

Key rotation

To rotate the server-side signing key without a flag-day, construct the client with the new and previous keys via the std::vector<std::string> overload; the SDK accepts a signature matching any entry:

authforge::AuthForgeClient client(
    "YOUR_APP_ID",
    "YOUR_APP_SECRET",
    std::vector<std::string>{ "NEW_PUBLIC_KEY", "PREVIOUS_PUBLIC_KEY" }
);

client.GetPublicKeys() returns the full trust list. A comma-separated single string ("NEW,PREVIOUS") works too, for env-var convenience.

Billing

  • One Login() or ValidateLicense() call = 1 credit (one /auth/validate debit each).
  • 10 online check-ins on the same session = 1 credit (debited on every 10th successful heartbeat).
  • The default grace period policy costs nothing after activation: no network calls are made until the next activation.

A desktop app with online check-ins running 6h/day at a 15-minute interval burns ~3-4 credits/day. /auth/heartbeat is limited to 6 requests/minute per license key, so keep intervals at 10 seconds or higher and choose cadence based on revocation speed needs (revocations always land on the next check-in).

Methods

Method Returns Description
Login(const std::string&) bool Activates the key online and stores the signed session (sessionToken, expiresIn, appVariables, licenseVariables)
ValidateLicense(const std::string&) ValidateLicenseResult Same /auth/validate + signatures as Login; does not persist session or start background checks; never calls onFailure or std::exit; inspect valid / errorCode
SelfBan(...) bool Requests /auth/selfban to blacklist HWID/IP and optionally revoke (session-authenticated only)
LoginFromFile(const std::string&) bool Authorizes from an offline .authforge file (path or text) with no network; never starts background checks; failures go to onFailure("offline_login_failed", …)
VerifyLicenseFile(const std::string&, long long nowEpochMs = 0) VerifyLicenseFileResult Verifies a .authforge file with this client's app id / keys / HWID without changing state
GetOfflineLicense() std::optional<OfflineLicense> Metadata of the offline file in use (jti, expiresAt, hwidPolicy, …)
GetSessionKind() SessionKind SessionKind::Online, SessionKind::Offline, or SessionKind::None when logged out
GetHwid() const std::string& The HWID this client sends (or hwidOverride); customers share it to receive a bound file
CreateActivationRequest(const ActivationRequestOptions& = {}) std::string Unsigned .authforge-request for this machine. No network, no secret. Hostname omitted unless includeMachineName
Logout() void Stops background checks and clears all session/auth state
IsAuthenticated() bool True when an active authenticated session exists
GetSessionDataJson() std::optional<std::string> Full decoded payload JSON
GetAppVariablesJson() std::optional<std::string> App variables JSON (if present)
GetLicenseVariablesJson() std::optional<std::string> License variables JSON (if present)

Grace period and online check-ins

Grace period (default). After a successful online activation, the app keeps running on the Ed25519-signed session without contacting AuthForge. The background loop re-verifies the signed session locally and triggers failure with session_expired when the grace period ends. The grace period equals the session TTL: default 24h, and the server clamps requested values (ttlSeconds) to 1h to 7d. This is session continuation after one successful online activation, not persistent offline licensing, and a mid-session revocation cannot take effect until the next online activation.

Online check-ins (opt-in). Construct the client with authforge::OnlineHeartbeat::On and the SDK calls /auth/heartbeat every heartbeatInterval seconds with a fresh nonce, verifies signature + nonce, and triggers failure on invalid session state. Choose this for fast revocation and concurrent-use detection.

Offline license files (.authforge)

For machines that never connect to the internet, the operator mints a signed offline license file in the AuthForge dashboard (License page -> Mint .authforge file) or via POST /v1/licenses/{licenseKey}/offline-files. The file is a standalone Ed25519-signed document; the SDK verifies it with only your app public key and the machine HWID. It never contacts AuthForge and never starts the background thread. Pass an empty appSecret so the air-gapped binary does not contain the App Secret.

Grace period (default) Offline license file
Needs network Once, at Login() Never on the end machine
What is verified Signed session from /auth/validate Signed document minted in the cloud
Lifetime Session TTL: 1h to 7d Operator-chosen expiry or lifetime (perpetual licenses only)
Revocation Picked up at the next online validate / check-in Not reachable: the file stays valid until its own expiry
Cost 1 credit per Login() 1 credit per mint; verifying is free 
authforge::AuthForgeClient client(
    "YOUR_APP_ID",
    "",  // LoginFromFile does not use the App Secret; do not ship it in air-gapped builds
    "YOUR_PUBLIC_KEY",
    authforge::OnlineHeartbeat::Off, 900, authforge::AuthForgeClient::kDefaultApiBaseUrl,
    [](const std::string &reason, const std::exception *exc) {
      std::cerr << reason << (exc ? std::string(": ") + exc->what() : "") << "\n";
    });

// 1. Write an activation request the operator drops into the mint dialog:
std::string request = client.CreateActivationRequest();

// 2. Later, authorize from the minted file (path or armored text). No network.
if (client.LoginFromFile("license.authforge")) {
  const auto info = client.GetOfflineLicense();
  std::cout << "Offline license OK until " << (info->expiresAt ? *info->expiresAt : "forever") << "\n";
}

Collect the HWID from the same SDK build that will load the file: fingerprints are not portable across SDKs or languages. After LoginFromFile(), GetSessionKind() returns SessionKind::Offline (SessionKind::Online after Login(), SessionKind::None when logged out).

authforge::VerifyLicenseFile(text, appId, publicKeys, hwid) (free function) and client.VerifyLicenseFile(pathOrText) perform the same checks without touching client state and return a VerifyLicenseFileResult (ok, error, license). Failure codes, in check order: bad_armor, bad_signature, unsupported_version, malformed_payload, wrong_app, expired, hwid_mismatch. LoginFromFile() reports them through onFailure("offline_login_failed", &exc) (with exc.what() = code) and returns false; it never calls std::exit.

File format (version 1): PEM-style armor with informational headers, a base64 JSON payload (v, appId, licenseKey, jti, kid, issuedAt, expiresAt, hwid policy, optional label/variable snapshots) and a detached Ed25519 signature over the UTF-8 bytes of the base64 payload string - the same contract as /auth/validate. See offline_license_vectors.json for conformance vectors and tests/offline_vectors_test.cpp (build with -DAUTHFORGE_BUILD_TESTS=ON, run with ctest).

Migrating from heartbeatMode

Earlier versions took a std::string heartbeatMode ("LOCAL" or "SERVER") as the 4th constructor parameter. That parameter is replaced by authforge::OnlineHeartbeat:

  • "LOCAL" maps to the default (grace period behavior): drop the argument entirely.
  • "SERVER" maps to authforge::OnlineHeartbeat::On.
// Before:
authforge::AuthForgeClient client("APP_ID", "APP_SECRET", "PUBLIC_KEY", "LOCAL");
// After (grace period is the default):
authforge::AuthForgeClient client("APP_ID", "APP_SECRET", "PUBLIC_KEY");

// Before:
authforge::AuthForgeClient client("APP_ID", "APP_SECRET", "PUBLIC_KEY", "SERVER");
// After:
authforge::AuthForgeClient client("APP_ID", "APP_SECRET", "PUBLIC_KEY",
                                  authforge::OnlineHeartbeat::On);

The old string-mode constructors still work and behave exactly as before, but they emit a deprecation warning at compile time.

Failure Handling

If authentication fails, the SDK calls your onFailure callback if one is provided. If no callback is set, the SDK calls std::exit(1) to terminate the process. This is intentional: it prevents your app from running without a valid license.

ValidateLicense() always returns a ValidateLicenseResult and does not invoke onFailure or exit the process.

Recognized server errors: invalid_app, invalid_key, expired, revoked, hwid_mismatch, no_credits, app_burn_cap_reached, blocked, rate_limited, replay_detected, app_disabled, session_expired, revoke_requires_session, bad_request, malformed_request, system_error

Request retries are automatic inside the internal HTTP layer:

  • rate_limited: retry after 2s, then 5s (max 3 attempts total)
  • network failure: retry once after 2s
  • every retry regenerates a fresh nonce
authforge::AuthForgeClient client(
    "YOUR_APP_ID",
    "YOUR_APP_SECRET",
    "YOUR_PUBLIC_KEY",
    authforge::OnlineHeartbeat::On,
    900,
    authforge::AuthForgeClient::kDefaultApiBaseUrl,
    [](const std::string& reason, const std::exception* exc) {
        std::cerr << "Auth failed: " << reason << std::endl;
        if (exc) std::cerr << "Details: " << exc->what() << std::endl;
        std::exit(1);
    }
);

Self-ban (tamper response)

Use SelfBan(...) when anti-tamper checks trigger:

// Post-session (authenticated): defaults to revoke + HWID/IP blacklist.
client.SelfBan();

// Pre-session: pass license key, SDK automatically disables revokeLicense.
client.SelfBan("AF-XXXX-XXXX-XXXX");

// Custom flags:
client.SelfBan("", "", false, true, true);

SelfBan(...) chooses request mode automatically:

  • Uses post-session mode when a session token is available (sessionToken arg or current SDK session).
  • Falls back to pre-session mode with licenseKey + nonce + app secret.
  • In pre-session mode, revoke is always disabled client-side to avoid unsafe key revocations.
  • Not available after LoginFromFile(): offline sessions have no server session, so SelfBan() with no explicit licenseKey / sessionToken returns false and reports onFailure("selfban_failed", &exc) with exc.what() = offline_session, without contacting the server.

How It Works

  1. Activate: Login uses hwidOverride when non-empty; otherwise it collects a hardware fingerprint (MAC, CPU, disk serial). It then generates a random nonce and sends everything to the AuthForge API. The server validates the license key, binds the HWID, deducts a credit, and returns a signed payload. The SDK verifies the Ed25519 signature and nonce to prevent replay attacks.

  2. Background checks: a detached background thread runs at the configured interval. By default it re-verifies the stored signed session locally and enforces the grace period without network calls. With online check-ins enabled, it instead sends a fresh nonce to /auth/heartbeat and verifies the response.

  3. Crypto: both /validate and /heartbeat responses are signed by AuthForge with your app's Ed25519 private key. The SDK verifies every signed payload using your configured publicKey and rejects tampered responses.

Test Vectors

The shared test_vectors.json file validates cross-language Ed25519 verification behavior. offline_license_vectors.json (generated from a fixed test seed in the Node SDK repo) is the cross-SDK conformance suite for .authforge offline license files: good files plus the bad_signature, wrong key, wrong_app, expired, hwid_mismatch, unsupported_version and bad_armor rejects. Run it with:

cmake -S . -B build -DAUTHFORGE_BUILD_TESTS=ON
cmake --build build
ctest --test-dir build --output-on-failure

Requirements

  • C++17
  • libsodium
  • OpenSSL
  • libcurl

License

MIT

About

Official C++ SDK for AuthForge — license key authentication with HMAC-verified heartbeats

authforge.cc

Topics

apicpplicensinglicensing-apilicensing-as-a-service

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