fix: Update DecryptionMaterials code to support legacy custom CMMs

src/main/java/com/amazonaws/encryptionsdk/CMMHandler.java

@@ -10,7 +10,6 @@
 import com.amazonaws.encryptionsdk.model.EncryptionMaterialsHandler;
 import com.amazonaws.encryptionsdk.model.EncryptionMaterialsRequest;
 import com.amazonaws.encryptionsdk.model.KeyBlob;
-
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.List;
@@ -65,10 +64,10 @@ private GetEncryptionMaterialsInput getEncryptionMaterialsRequestInput(
   public DecryptionMaterialsHandler decryptMaterials(
       DecryptionMaterialsRequest request, CommitmentPolicy commitmentPolicy) {
     if (cmm != null && mplCMM == null) {
-      // This is an implementation of the legacy native CryptoMaterialsManager interface from ESDK-Java.
+      // This is an implementation of the legacy native CryptoMaterialsManager interface from
+      // ESDK-Java.
       DecryptionMaterials materials = cmm.decryptMaterials(request);
-      if (materials.getEncryptionContext().isEmpty()
-        && !request.getEncryptionContext().isEmpty()) {
+      if (materials.getEncryptionContext().isEmpty() && !request.getEncryptionContext().isEmpty()) {
         // If the request specified an encryption context,
         // and we are using the legacy native CMM,
         // add the encryptionContext to the materials.
@@ -82,7 +81,8 @@ public DecryptionMaterialsHandler decryptMaterials(
         // It now sets the encryptionContext attribute with the value from the ciphertext's headers.
         //
         // But custom CMMs' behavior was not updated.
-        // However, there is no custom CMM before version 3.0 that could set an encryptionContext attribute.
+        // However, there is no custom CMM before version 3.0 that could set an encryptionContext
+        // attribute.
         // The encryptionContext attribute was only introduced to decryptMaterials objects
         // in ESDK 3.0, so no CMM could have configured this attribute before 3.0.
         // As a result, the ESDK assumes that any native CMM
@@ -91,9 +91,8 @@ public DecryptionMaterialsHandler decryptMaterials(
         //
         // If a custom CMM implementation conflicts with this assumption.
         // that CMM implementation MUST move to the MPL.
-        materials = materials.toBuilder()
-                .setEncryptionContext(request.getEncryptionContext())
-                .build();
+        materials =
+            materials.toBuilder().setEncryptionContext(request.getEncryptionContext()).build();
       }
       return new DecryptionMaterialsHandler(materials);
     } else {

src/test/java/com/amazonaws/crypto/examples/v2/CustomCMMExampleTest.java

@@ -8,24 +8,21 @@
 import com.amazonaws.encryptionsdk.kms.KmsMasterKeyProvider;
 import org.junit.Test;
 
-
 public class CustomCMMExampleTest {
 
   @Test
   public void testCustomCMMExample() {
-    CryptoMaterialsManager cmm = new CustomCMMExample.SigningSuiteOnlyCMM(
-            KmsMasterKeyProvider.builder().buildStrict(KMSTestFixtures.US_WEST_2_KEY_ID)
-    );
+    CryptoMaterialsManager cmm =
+        new CustomCMMExample.SigningSuiteOnlyCMM(
+            KmsMasterKeyProvider.builder().buildStrict(KMSTestFixtures.US_WEST_2_KEY_ID));
     CustomCMMExample.encryptAndDecryptWithCMM(cmm);
   }
 
   @Test
   public void testV2Cmm() {
-    V2DefaultCryptoMaterialsManager cmm = new V2DefaultCryptoMaterialsManager(
-            KmsMasterKeyProvider.builder().buildStrict(KMSTestFixtures.US_WEST_2_KEY_ID)
-    );
+    V2DefaultCryptoMaterialsManager cmm =
+        new V2DefaultCryptoMaterialsManager(
+            KmsMasterKeyProvider.builder().buildStrict(KMSTestFixtures.US_WEST_2_KEY_ID));
     CustomCMMExample.encryptAndDecryptWithCMM(cmm);
   }
 }
-
-

src/test/java/com/amazonaws/crypto/examples/v2/V2DefaultCryptoMaterialsManager.java

@@ -1,5 +1,7 @@
 package com.amazonaws.crypto.examples.v2;
 
+import static com.amazonaws.encryptionsdk.internal.Utils.assertNonNull;
+
 import com.amazonaws.encryptionsdk.CommitmentPolicy;
 import com.amazonaws.encryptionsdk.CryptoAlgorithm;
 import com.amazonaws.encryptionsdk.CryptoMaterialsManager;
@@ -16,7 +18,6 @@
 import com.amazonaws.encryptionsdk.model.EncryptionMaterials;
 import com.amazonaws.encryptionsdk.model.EncryptionMaterialsRequest;
 import com.amazonaws.encryptionsdk.model.KeyBlob;
-
 import java.security.GeneralSecurityException;
 import java.security.KeyPair;
 import java.security.PublicKey;
@@ -25,28 +26,26 @@
 import java.util.List;
 import java.util.Map;
 
-import static com.amazonaws.encryptionsdk.internal.Utils.assertNonNull;
-
 /*
-  This is a copy-paste of the DefaultCryptoMaterialsManager implementation
-  from the final commit of the V2 ESDK: 1870a082358d59e32c60d74116d6f43c0efa466b
-  ESDK V3 implicitly changed the contract between CMMs and the ESDK.
-  After V3, DecryptMaterials has an `encryptionContext` attribute,
-  and CMMs are expected to set this attribute.
-  The V3 commit modified this DefaultCMM's `decryptMaterials` implementation
-  to set encryptionContext on returned DecryptionMaterials objects.
-  However, there are custom implementations of the legacy native CMM
-  that do not set encryptionContext.
-  This CMM is used to explicitly assert that the V2 implementation of
-  the DefaultCMM is compatible with V3 logic,
-  which implicitly asserts that custom implementations of V2-compatible CMMs
-  are also compatible with V3 logic.
- */
+ This is a copy-paste of the DefaultCryptoMaterialsManager implementation
+ from the final commit of the V2 ESDK: 1870a082358d59e32c60d74116d6f43c0efa466b
+ ESDK V3 implicitly changed the contract between CMMs and the ESDK.
+ After V3, DecryptMaterials has an `encryptionContext` attribute,
+ and CMMs are expected to set this attribute.
+ The V3 commit modified this DefaultCMM's `decryptMaterials` implementation
+ to set encryptionContext on returned DecryptionMaterials objects.
+ However, there are custom implementations of the legacy native CMM
+ that do not set encryptionContext.
+ This CMM is used to explicitly assert that the V2 implementation of
+ the DefaultCMM is compatible with V3 logic,
+ which implicitly asserts that custom implementations of V2-compatible CMMs
+ are also compatible with V3 logic.
+*/
 public class V2DefaultCryptoMaterialsManager implements CryptoMaterialsManager {
   private final MasterKeyProvider<?> mkp;
 
   private final CryptoAlgorithm DEFAULT_CRYPTO_ALGORITHM =
-          CryptoAlgorithm.ALG_AES_256_GCM_IV12_TAG16_HKDF_SHA384_ECDSA_P384;
+      CryptoAlgorithm.ALG_AES_256_GCM_IV12_TAG16_HKDF_SHA384_ECDSA_P384;
 
   /** @param mkp The master key provider to delegate to */
   public V2DefaultCryptoMaterialsManager(MasterKeyProvider<?> mkp) {
@@ -73,7 +72,7 @@ public EncryptionMaterials getMaterialsForEncrypt(EncryptionMaterialsRequest req
         trailingKeys = generateTrailingSigKeyPair(algo);
         if (context.containsKey(Constants.EC_PUBLIC_KEY_FIELD)) {
           throw new IllegalArgumentException(
-                  "EncryptionContext contains reserved field " + Constants.EC_PUBLIC_KEY_FIELD);
+              "EncryptionContext contains reserved field " + Constants.EC_PUBLIC_KEY_FIELD);
         }
         // make mutable
         context = new HashMap<>(context);
@@ -95,8 +94,8 @@ public EncryptionMaterials getMaterialsForEncrypt(EncryptionMaterialsRequest req
 
     @SuppressWarnings("unchecked")
     final List<MasterKey> mks =
-            (List<MasterKey>)
-                    assertNonNull(mkp, "provider").getMasterKeysForEncryption(mkRequestBuilder.build());
+        (List<MasterKey>)
+            assertNonNull(mkp, "provider").getMasterKeysForEncryption(mkRequestBuilder.build());
 
     if (mks.isEmpty()) {
       throw new IllegalArgumentException("No master keys provided");
@@ -114,20 +113,20 @@ public EncryptionMaterials getMaterialsForEncrypt(EncryptionMaterialsRequest req
 
     //noinspection unchecked
     return EncryptionMaterials.newBuilder()
-            .setAlgorithm(algo)
-            .setCleartextDataKey(dataKey.getKey())
-            .setEncryptedDataKeys(keyBlobs)
-            .setEncryptionContext(context)
-            .setTrailingSignatureKey(trailingKeys == null ? null : trailingKeys.getPrivate())
-            .setMasterKeys(mks)
-            .build();
+        .setAlgorithm(algo)
+        .setCleartextDataKey(dataKey.getKey())
+        .setEncryptedDataKeys(keyBlobs)
+        .setEncryptionContext(context)
+        .setTrailingSignatureKey(trailingKeys == null ? null : trailingKeys.getPrivate())
+        .setMasterKeys(mks)
+        .build();
   }
 
   @Override
   public DecryptionMaterials decryptMaterials(DecryptionMaterialsRequest request) {
     DataKey<?> dataKey =
-            mkp.decryptDataKey(
-                    request.getAlgorithm(), request.getEncryptedDataKeys(), request.getEncryptionContext());
+        mkp.decryptDataKey(
+            request.getAlgorithm(), request.getEncryptedDataKeys(), request.getEncryptionContext());
 
     if (dataKey == null) {
       throw new CannotUnwrapDataKeyException("Could not decrypt any data keys");
@@ -151,9 +150,9 @@ public DecryptionMaterials decryptMaterials(DecryptionMaterialsRequest request)
     }
 
     return DecryptionMaterials.newBuilder()
-            .setDataKey(dataKey)
-            .setTrailingSignatureKey(pubKey)
-            .build();
+        .setDataKey(dataKey)
+        .setTrailingSignatureKey(pubKey)
+        .build();
   }
 
   private PublicKey deserializeTrailingKeyFromEc(CryptoAlgorithm algo, String pubKey) {
@@ -162,11 +161,11 @@ private PublicKey deserializeTrailingKeyFromEc(CryptoAlgorithm algo, String pubK
 
   private static String serializeTrailingKeyForEc(CryptoAlgorithm algo, KeyPair trailingKeys) {
     return TrailingSignatureAlgorithm.forCryptoAlgorithm(algo)
-            .serializePublicKey(trailingKeys.getPublic());
+        .serializePublicKey(trailingKeys.getPublic());
   }
 
   private static KeyPair generateTrailingSigKeyPair(CryptoAlgorithm algo)
-          throws GeneralSecurityException {
+      throws GeneralSecurityException {
     return TrailingSignatureAlgorithm.forCryptoAlgorithm(algo).generateKey();
   }
 }

src/test/java/com/amazonaws/encryptionsdk/AllTestsSuite.java

@@ -50,8 +50,8 @@
 import com.amazonaws.encryptionsdk.model.CipherBlockHeadersTest;
 import com.amazonaws.encryptionsdk.model.CipherFrameHeadersTest;
 import com.amazonaws.encryptionsdk.model.CiphertextHeadersTest;
-import com.amazonaws.encryptionsdk.model.DecryptionMaterialsTest;
 import com.amazonaws.encryptionsdk.model.DecryptionMaterialsRequestTest;
+import com.amazonaws.encryptionsdk.model.DecryptionMaterialsTest;
 import com.amazonaws.encryptionsdk.model.EncryptionMaterialsRequestTest;
 import com.amazonaws.encryptionsdk.model.KeyBlobTest;
 import com.amazonaws.encryptionsdk.multi.MultipleMasterKeyTest;