Add Cryptography API support with encrypt/decrypt operations

- Add EncryptRequestAlpha1 and DecryptRequestAlpha1 domain classes
- Implement encrypt() and decrypt() methods in DaprPreviewClient
- Add CryptoExample and StreamingCryptoExample with documentation
- Add integration tests for crypto operations
- Add localstorage crypto component configuration

Author: siri-varma

.github/workflows/build.yml

@@ -32,7 +32,7 @@ jobs:
       - name: Run tests
         run: ./mvnw clean install -B -q -DskipITs=true
       - name: Codecov
-        uses: codecov/codecov-action@v5.5.1
+        uses: codecov/codecov-action@v5.5.2
       - name: Upload test report for sdk
         uses: actions/upload-artifact@v5
         with:

.github/workflows/validate.yml

@@ -113,6 +113,10 @@ jobs:
         run: sleep 30 && docker logs dapr_scheduler && nc -vz localhost 50006
       - name: Install jars
         run: ./mvnw clean install -DskipTests -q
+      - name: Validate crypto example
+        working-directory: ./examples
+        run: |
+          mm.py ./src/main/java/io/dapr/examples/crypto/README.md
       - name: Validate workflows example
         working-directory: ./examples
         run: |
@@ -186,3 +190,5 @@ jobs:
         run: |
           mm.py ./src/main/java/io/dapr/examples/pubsub/stream/README.md
 
+
+

examples/components/crypto/keys/.gitkeep

@@ -0,0 +1,12 @@
+apiVersion: dapr.io/v1alpha1
+kind: Component
+metadata:
+  name: localstoragecrypto
+spec:
+  type: crypto.dapr.localstorage
+  version: v1
+  metadata:
+    # Path to the directory containing keys (PEM files)
+    # This path is relative to the resources-path directory
+    - name: path
+      value: "C:/Users/svegiraju/IdeaProjects/java-sdk/examples/components/crypto/keys/"

examples/components/crypto/localstorage.yaml

@@ -0,0 +1,173 @@
+/*
+ * Copyright 2021 The Dapr Authors
+ * 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.
+*/
+
+package io.dapr.examples.crypto;
+
+import io.dapr.client.DaprClientBuilder;
+import io.dapr.client.DaprPreviewClient;
+import io.dapr.client.domain.DecryptRequestAlpha1;
+import io.dapr.client.domain.EncryptRequestAlpha1;
+import io.dapr.config.Properties;
+import io.dapr.config.Property;
+import reactor.core.publisher.Flux;
+
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.security.KeyPair;
+import java.security.KeyPairGenerator;
+import java.security.NoSuchAlgorithmException;
+import java.util.Base64;
+import java.util.Map;
+
+/**
+ * CryptoExample demonstrates using the Dapr Cryptography building block
+ * to encrypt and decrypt data using a cryptography component.
+ *
+ * <p>This example shows:
+ * <ul>
+ *   <li>Encrypting plaintext data with a specified key and algorithm</li>
+ *   <li>Decrypting ciphertext data back to plaintext</li>
+ *   <li>Automatic key generation if keys don't exist</li>
+ * </ul>
+ *
+ * <p>Prerequisites:
+ * <ul>
+ *   <li>Dapr installed and initialized</li>
+ *   <li>A cryptography component configured (e.g., local storage crypto)</li>
+ * </ul>
+ */
+public class CryptoExample {
+
+  private static final String CRYPTO_COMPONENT_NAME = "localstoragecrypto";
+  private static final String KEY_NAME = "rsa-private-key";
+  private static final String KEY_WRAP_ALGORITHM = "RSA";
+  private static final String KEYS_DIR = "components/crypto/keys";
+
+  /**
+   * The main method demonstrating encryption and decryption with Dapr.
+   *
+   * @param args Command line arguments (unused).
+   */
+  public static void main(String[] args) throws Exception {
+    // Generate keys if they don't exist
+    generateKeysIfNeeded();
+
+    Map<Property<?>, String> overrides = Map.of(
+        Properties.HTTP_PORT, "3500",
+        Properties.GRPC_PORT, "50001"
+    );
+
+    try (DaprPreviewClient client = new DaprClientBuilder().withPropertyOverrides(overrides).buildPreviewClient()) {
+
+      String originalMessage = "This is a secret message";
+      byte[] plainText = originalMessage.getBytes(StandardCharsets.UTF_8);
+
+      System.out.println("=== Dapr Cryptography Example ===");
+      System.out.println("Original message: " + originalMessage);
+      System.out.println();
+
+      // Encrypt the message
+      System.out.println("Encrypting message...");
+      EncryptRequestAlpha1 encryptRequest = new EncryptRequestAlpha1(
+          CRYPTO_COMPONENT_NAME,
+          Flux.just(plainText),
+          KEY_NAME,
+          KEY_WRAP_ALGORITHM
+      );
+
+      byte[] encryptedData = client.encrypt(encryptRequest)
+          .collectList()
+          .map(CryptoExample::combineChunks)
+          .block();
+
+      System.out.println("Encryption successful!");
+      System.out.println("Encrypted data length: " + encryptedData.length + " bytes");
+      System.out.println();
+
+      // Decrypt the message
+      System.out.println("Decrypting message...");
+      DecryptRequestAlpha1 decryptRequest = new DecryptRequestAlpha1(
+          CRYPTO_COMPONENT_NAME,
+          Flux.just(encryptedData)
+      );
+
+      byte[] decryptedData = client.decrypt(decryptRequest)
+          .collectList()
+          .map(CryptoExample::combineChunks)
+          .block();
+
+      String decryptedMessage = new String(decryptedData, StandardCharsets.UTF_8);
+      System.out.println("Decryption successful!");
+      System.out.println("Decrypted message: " + decryptedMessage);
+      System.out.println();
+
+      if (originalMessage.equals(decryptedMessage)) {
+        System.out.println("SUCCESS: The decrypted message matches the original.");
+      } else {
+        System.out.println("ERROR: The decrypted message does not match the original.");
+      }
+
+    } catch (Exception e) {
+      System.err.println("Error during crypto operations: " + e.getMessage());
+      throw new RuntimeException(e);
+    }
+  }
+
+  /**
+   * Generates RSA key pair if the key file doesn't exist.
+   */
+  private static void generateKeysIfNeeded() throws NoSuchAlgorithmException, IOException {
+    Path keysDir = Paths.get(KEYS_DIR);
+    Path keyFile = keysDir.resolve(KEY_NAME + ".pem");
+
+    if (Files.exists(keyFile)) {
+      System.out.println("Using existing key: " + keyFile.toAbsolutePath());
+      return;
+    }
+
+    System.out.println("Generating RSA key pair...");
+    Files.createDirectories(keysDir);
+
+    KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");
+    keyGen.initialize(4096);
+    KeyPair keyPair = keyGen.generateKeyPair();
+
+    String privateKeyPem = "-----BEGIN PRIVATE KEY-----\n"
+        + Base64.getMimeEncoder(64, "\n".getBytes()).encodeToString(keyPair.getPrivate().getEncoded())
+        + "\n-----END PRIVATE KEY-----\n";
+
+    String publicKeyPem = "-----BEGIN PUBLIC KEY-----\n"
+        + Base64.getMimeEncoder(64, "\n".getBytes()).encodeToString(keyPair.getPublic().getEncoded())
+        + "\n-----END PUBLIC KEY-----\n";
+
+    Files.writeString(keyFile, privateKeyPem + publicKeyPem);
+    System.out.println("Key generated: " + keyFile.toAbsolutePath());
+  }
+
+  /**
+   * Combines byte array chunks into a single byte array.
+   */
+  private static byte[] combineChunks(java.util.List<byte[]> chunks) {
+    int totalSize = chunks.stream().mapToInt(chunk -> chunk.length).sum();
+    byte[] result = new byte[totalSize];
+    int pos = 0;
+    for (byte[] chunk : chunks) {
+      System.arraycopy(chunk, 0, result, pos, chunk.length);
+      pos += chunk.length;
+    }
+    return result;
+  }
+}

examples/src/main/java/io/dapr/examples/crypto/CryptoExample.java

@@ -0,0 +1,178 @@
+## Dapr Cryptography API Examples
+
+This example provides the different capabilities provided by Dapr Java SDK for Cryptography. For further information about Cryptography APIs please refer to [this link](https://docs.dapr.io/developing-applications/building-blocks/cryptography/cryptography-overview/)
+
+### Using the Cryptography API
+
+The Java SDK exposes several methods for this -
+* `client.encrypt(...)` for encrypting data using a cryptography component.
+* `client.decrypt(...)` for decrypting data using a cryptography component.
+
+## Pre-requisites
+
+* [Dapr CLI](https://docs.dapr.io/getting-started/install-dapr-cli/).
+* Java JDK 11 (or greater):
+    * [Microsoft JDK 11](https://docs.microsoft.com/en-us/java/openjdk/download#openjdk-11)
+    * [Oracle JDK 11](https://www.oracle.com/technetwork/java/javase/downloads/index.html#JDK11)
+    * [OpenJDK 11](https://jdk.java.net/11/)
+* [Apache Maven](https://maven.apache.org/install.html) version 3.x.
+
+### Checking out the code
+
+Clone this repository:
+
+```sh
+git clone https://github.com/dapr/java-sdk.git
+cd java-sdk
+```
+
+Then build the Maven project:
+
+```sh
+# make sure you are in the `java-sdk` directory.
+mvn install
+```
+
+Then get into the examples directory:
+
+```sh
+cd examples
+```
+
+### Initialize Dapr
+
+Run `dapr init` to initialize Dapr in Self-Hosted Mode if it's not already initialized.
+
+### Running the Example
+
+This example uses the Java SDK Dapr client to **Encrypt and Decrypt** data. The example automatically generates RSA keys if they don't exist.
+
+#### Example 1: Basic Crypto Example
+
+`CryptoExample.java` demonstrates basic encryption and decryption of a simple message.
+
+```java
+public class CryptoExample {
+  private static final String CRYPTO_COMPONENT_NAME = "localstoragecrypto";
+  private static final String KEY_NAME = "rsa-private-key";
+  private static final String KEY_WRAP_ALGORITHM = "RSA";
+
+  public static void main(String[] args) {
+    try (DaprPreviewClient client = new DaprClientBuilder().buildPreviewClient()) {
+
+      String originalMessage = "This is a secret message";
+      byte[] plainText = originalMessage.getBytes(StandardCharsets.UTF_8);
+
+      // Encrypt the message
+      EncryptRequestAlpha1 encryptRequest = new EncryptRequestAlpha1(
+          CRYPTO_COMPONENT_NAME,
+          Flux.just(plainText),
+          KEY_NAME,
+          KEY_WRAP_ALGORITHM
+      );
+
+      byte[] encryptedData = client.encrypt(encryptRequest)
+          .collectList()
+          .map(chunks -> /* combine chunks */)
+          .block();
+
+      // Decrypt the message
+      DecryptRequestAlpha1 decryptRequest = new DecryptRequestAlpha1(
+          CRYPTO_COMPONENT_NAME,
+          Flux.just(encryptedData)
+      );
+
+      byte[] decryptedData = client.decrypt(decryptRequest)
+          .collectList()
+          .map(chunks -> /* combine chunks */)
+          .block();
+    }
+  }
+}
+```
+
+Use the following command to run this example:
+
+<!-- STEP
+name: Generate Crypto Keys
+expected_stdout_lines:
+  - "Keys generated successfully"
+background: false
+output_match_mode: substring
+-->
+
+```bash
+mkdir -p ./components/crypto/keys && openssl genrsa -out ./components/crypto/keys/rsa-private-key.pem 4096 && openssl rsa -in ./components/crypto/keys/rsa-private-key.pem -pubout -out ./components/crypto/keys/rsa-private-key.pub.pem && echo "Keys generated successfully"
+```
+
+<!-- END_STEP -->
+
+<!-- STEP
+name: Run Crypto Example
+expected_stdout_lines:
+  - "== APP == SUCCESS: The decrypted message matches the original."
+background: true
+output_match_mode: substring
+sleep: 10
+-->
+
+```bash
+dapr run --resources-path ./components/crypto --app-id crypto-app --dapr-http-port 3500 --dapr-grpc-port 50001 -- java -jar target/dapr-java-sdk-examples-exec.jar io.dapr.examples.crypto.CryptoExample
+```
+
+<!-- END_STEP -->
+
+#### Example 2: Streaming Crypto Example
+
+`StreamingCryptoExample.java` demonstrates advanced scenarios including:
+- Multi-chunk data encryption
+- Large data encryption (100KB+)
+- Custom encryption ciphers
+
+```bash
+dapr run --resources-path ./components/crypto --app-id crypto-app --dapr-http-port 3500 --dapr-grpc-port 50001 -- java -jar target/dapr-java-sdk-examples-exec.jar io.dapr.examples.crypto.StreamingCryptoExample
+```
+
+### Sample Output
+
+```
+=== Dapr Cryptography Example ===
+Original message: This is a secret message
+
+Encrypting message...
+Encryption successful!
+Encrypted data length: 512 bytes
+
+Decrypting message...
+Decryption successful!
+Decrypted message: This is a secret message
+
+SUCCESS: The decrypted message matches the original.
+```
+
+### Supported Key Wrap Algorithms
+
+The following key wrap algorithms are supported:
+- `A256KW` (alias: `AES`) - AES key wrap
+- `A128CBC`, `A192CBC`, `A256CBC` - AES CBC modes
+- `RSA-OAEP-256` (alias: `RSA`) - RSA OAEP with SHA-256
+
+### Supported Data Encryption Ciphers
+
+Optional data encryption ciphers:
+- `aes-gcm` (default) - AES in GCM mode
+- `chacha20-poly1305` - ChaCha20-Poly1305 cipher
+
+### Cleanup
+
+To stop the app, run (or press CTRL+C):
+
+<!-- STEP
+name: Cleanup
+-->
+
+```bash
+dapr stop --app-id crypto-app
+```
+
+<!-- END_STEP -->