#BAEL-6958: add test source

Author: hmdrzsharifi

core-java-modules/core-java-security-5/src/test/java/com/baeldung/kem/KemUtilsIntegrationTest.java

@@ -0,0 +1,52 @@
+package com.baeldung.kem;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.security.KeyPair;
+import java.security.KeyPairGenerator;
+
+import javax.crypto.SecretKey;
+
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+public class KemUtilsIntegrationTest {
+    private static KeyPair keyPair;
+    public static final String KEM_ALGORITHM = "DHKEM";
+
+
+    @BeforeAll
+    static void setup() throws Exception {
+        KeyPairGenerator kpg = KeyPairGenerator.getInstance("X25519");
+        keyPair = kpg.generateKeyPair();
+    }
+
+    @Test
+    void givenKem_whenSenderEncapsulatesAndReceiverDecapsulates_thenSecretsMatch() throws Exception {
+        KemUtils.KemResult senderResult = KemUtils.encapsulate(KEM_ALGORITHM, keyPair.getPublic());
+        assertNotNull(senderResult.sharedSecret());
+        assertNotNull(senderResult.encapsulation());
+
+        KemUtils.KemResult receiverResult = KemUtils.decapsulate(KEM_ALGORITHM, keyPair.getPrivate(), senderResult.encapsulation());
+
+        SecretKey senderSecret = senderResult.sharedSecret();
+        SecretKey receiverSecret = receiverResult.sharedSecret();
+
+        assertArrayEquals(senderSecret.getEncoded(), receiverSecret.getEncoded(),
+            "Shared secrets from sender and receiver must match");
+    }
+
+    @Test
+    void givenDifferentReceiverKey_whenDecapsulate_thenFails() throws Exception {
+        KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
+        KeyPair wrongKeyPair = kpg.generateKeyPair();
+
+        KemUtils.KemResult senderResult = KemUtils.encapsulate(KEM_ALGORITHM, keyPair.getPublic());
+
+        assertThrows(Exception.class, () ->
+            KemUtils.decapsulate(KEM_ALGORITHM, wrongKeyPair.getPrivate(), senderResult.encapsulation()));
+    }
+
+}