Flow 1 – ML-KEM-512 Stream Encrypt / Decrypt (Detached JWET)

/*
 * Copyright 2025 ANKATech Solutions Inc
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * SPDX-License-Identifier: Apache-2.0
 */
package co.ankatech.ankasecure.sdk.examples;

import co.ankatech.ankasecure.sdk.AuthenticatedSdk;
import co.ankatech.ankasecure.sdk.model.DecryptResultMetadata;
import co.ankatech.ankasecure.sdk.model.EncryptResult;
import co.ankatech.ankasecure.sdk.util.FileIO;
import java.nio.file.Path;
import java.util.Properties;

import static co.ankatech.ankasecure.sdk.examples.ExampleUtil.*;

/**
 * Scenario 1 — End-to-End ML-KEM-512 Encryption (Streaming).
 *
 * <p>This scenario walks through a complete post-quantum data-plane round-trip
 * using the <strong>streaming</strong> endpoints of ANKASecure&copy;. In streaming
 * mode the service produces a <em>detached&nbsp;JWE</em> (General-JSON header + raw
 * ciphertext stream) instead of a single compact JWE string.</p>
 *
 * <ol>
 *   <li>Resolve a pre-provisioned <code>ML-KEM-512</code> key from the demo-cli
 *       playground (the SDK is data-plane-only — it does not create keys).</li>
 *   <li>Stream-encrypt a local file (detached JWE).</li>
 *   <li>Stream-decrypt the ciphertext.</li>
 *   <li>Validate round-trip integrity.</li>
 * </ol>
 *
 * <p><strong>Prerequisite:</strong> a {@code cli.properties} for the
 * {@code cli-reference} actor of the provisioned {@code demo-cli} playground,
 * carrying the {@code ankasecure.demo.kids} catalogue (emitted by the
 * demo-provisioning tool). Key lifecycle (generate/rotate/export) lives in
 * {@code cli-admin}, not the SDK.</p>
 *
 * <p><b>Implementation notes (Java&nbsp;21+):</b></p>
 * <ul>
 *   <li>All file handling relies on the {@link java.nio.file.Path} API.</li>
 *   <li>UTF-8 is enforced explicitly to avoid platform-dependent defaults.</li>
 *   <li>Temporary artefacts are written under <kbd>temp_files/</kbd>.</li>
 * </ul>
 *
 * <p><b>Thread-safety:</b> the class is stateless and immutable; a fresh
 * {@link AuthenticatedSdk} instance is created inside {@link #main(String[])}.</p>
 *
 * @author ANKATech Solutions Inc.
 * @since 3.0.0
 * @see ExampleUtil
 * @see ExamplePlaygroundKeys
 * @see AuthenticatedSdk
 */
public final class ExampleScenario1 {

    /** No instantiation &mdash; this class only exposes {@link #main(String[])}. */
    private ExampleScenario1() { }

    /**
     * Runs the ML-KEM-512 streaming encryption scenario on a pre-provisioned key.
     *
     * <p>Loads CLI properties, authenticates against ANKASecure&copy;, resolves a
     * pre-provisioned ML-KEM-512 playground key, and delegates to the scenario
     * logic. On any unrecoverable error the JVM terminates via
     * {@link ExampleUtil#fatal(String, Throwable)}.</p>
     *
     * @param args command-line arguments (ignored)
     */
    public static void main(String[] args) {

        System.out.println("===== SCENARIO 1 START =====");
        System.out.println("""
                Purpose :
                  * End-to-end ML-KEM-512 data-plane round-trip in streaming mode
                  * Demonstrates detached-JWE pipeline (encrypt -> decrypt) on a
                    pre-provisioned playground key
                Steps   :
                  1) Resolve pre-provisioned ML-KEM-512 key
                  2) Encrypt payload (detached JWE)
                  3) Decrypt ciphertext
                  4) Validate integrity
                --------------------------------------------------------------""");

        try {
            prepareWorkingDir();

            Properties            props      = loadProperties();
            AuthenticatedSdk      sdk        = authenticate(props);
            ExamplePlaygroundKeys playground = ExamplePlaygroundKeys.from(props, sdk);

            runScenario(sdk, playground);

        } catch (Exception ex) {
            fatal("Scenario 1 failed", ex);
        }

        System.out.println("===== SCENARIO 1 END =====");
    }

    /**
     * Executes the ML-KEM-512 streaming encryption scenario on a pre-provisioned key.
     *
     * <ol>
     *   <li>Create plaintext file.</li>
     *   <li>Resolve a pre-provisioned ML-KEM-512 key.</li>
     *   <li>Stream-encrypt to detached JWE.</li>
     *   <li>Stream-decrypt and validate integrity.</li>
     * </ol>
     *
     * @param sdk        an authenticated {@link AuthenticatedSdk} instance; must not be {@code null}
     * @param playground the pre-provisioned playground key resolver; must not be {@code null}
     * @throws Exception on any I/O or cryptographic failure
     */
    private static void runScenario(final AuthenticatedSdk sdk,
                                    final ExamplePlaygroundKeys playground) throws Exception {

        /* -- file system artefacts ----------------------------------------- */
        Path plainFile = TEMP_DIR.resolve("scenario1_plain.txt");
        Path encFile   = TEMP_DIR.resolve("scenario1.enc");
        Path decFile   = TEMP_DIR.resolve("scenario1.dec");

        /* 1 -- plaintext ---------------------------------------------------- */
        FileIO.writeUtf8(plainFile,
                "Hello Scenario-1 - streaming encryption demo!");
        System.out.println("[1] Plaintext ready           -> " + plainFile.toAbsolutePath());

        /* 2 -- resolve pre-provisioned key (data-plane SDK: no key creation) */
        final String kid = playground.kidForAlgorithm("ML-KEM-512");
        System.out.println("[2] Using pre-provisioned key -> kid = " + kid);

        /* 3 -- streaming encrypt (detached JWE) ----------------------------- */
        EncryptResult encMeta = sdk.encryptFileStream(kid, plainFile, encFile);
        System.out.println("[3] Ciphertext written        -> " + encFile.toAbsolutePath());
        printEncryptMeta(encMeta);

        /* 4 -- streaming decrypt -------------------------------------------- */
        DecryptResultMetadata decMeta = sdk.decryptFileStream(encFile, decFile);
        System.out.println("[4] Decrypted file            -> " + decFile.toAbsolutePath());
        printDecryptMeta(decMeta);

        /* 5 -- validation --------------------------------------------------- */
        String original  = FileIO.readUtf8(plainFile);
        String recovered = FileIO.readUtf8(decFile);
        System.out.println(original.equals(recovered)
                ? "[5] Validation OK - plaintext matches."
                : "[5] WARNING - plaintext mismatch!");
    }
}