Introduce null-safe transit operations.

Require non-null VaultTransitContext in VaultTransitOperations and refactor nonce/context bytes to null-safe values.

See gh-112.

spring-vault-core/src/main/java/org/springframework/vault/core/VaultTransitOperations.java

@@ -120,11 +120,11 @@ public interface VaultTransitOperations {
 	 *
 	 * @param keyName must not be empty or {@literal null}.
 	 * @param plaintext must not be empty or {@literal null}.
-	 * @param transitRequest may be {@literal null} if no request options provided.
+	 * @param transitRequest must not be {@literal null}. Use
+	 * {@link VaultTransitContext#empty()} if no request options provided.
 	 * @return cipher text.
 	 */
-	String encrypt(String keyName, byte[] plaintext,
-			@Nullable VaultTransitContext transitRequest);
+	String encrypt(String keyName, byte[] plaintext, VaultTransitContext transitRequest);
 
 	/**
 	 * Decrypts the provided plaintext using the named key.
@@ -140,11 +140,12 @@ public interface VaultTransitOperations {
 	 *
 	 * @param keyName must not be empty or {@literal null}.
 	 * @param ciphertext must not be empty or {@literal null}.
-	 * @param transitRequest may be {@literal null} if no request options provided.
+	 * @param transitContext must not be {@literal null}. Use
+	 * {@link VaultTransitContext#empty()} if no request options provided.
+	 * @return cipher text.
 	 * @return plain text.
 	 */
-	byte[] decrypt(String keyName, String ciphertext,
-			@Nullable VaultTransitContext transitRequest);
+	byte[] decrypt(String keyName, String ciphertext, VaultTransitContext transitContext);
 
 	/**
 	 * Rewrap the provided ciphertext using the latest version of the named key. Because
@@ -165,10 +166,10 @@ public interface VaultTransitOperations {
 	 *
 	 * @param keyName must not be empty or {@literal null}.
 	 * @param ciphertext must not be empty or {@literal null}.
-	 * @param transitRequest may be {@literal null} if no request options provided.
+	 * @param transitContext must not be {@literal null}. Use
+	 * {@link VaultTransitContext#empty()} if no request options provided.
 	 * @return cipher text.
 	 * @see #rotate(String)
 	 */
-	String rewrap(String keyName, String ciphertext,
-			@Nullable VaultTransitContext transitRequest);
+	String rewrap(String keyName, String ciphertext, VaultTransitContext transitContext);
 }

spring-vault-core/src/main/java/org/springframework/vault/core/VaultTransitTemplate.java

@@ -26,6 +26,7 @@ import lombok.Data;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.Base64Utils;
+import org.springframework.util.ObjectUtils;
 import org.springframework.vault.support.RawTransitKey;
 import org.springframework.vault.support.TransitKeyType;
 import org.springframework.vault.support.VaultResponse;
@@ -158,18 +159,17 @@ public class VaultTransitTemplate implements VaultTransitOperations {
 
 	@Override
 	public String encrypt(String keyName, byte[] plaintext,
-			@Nullable VaultTransitContext transitRequest) {
+			VaultTransitContext transitContext) {
 
 		Assert.hasText(keyName, "KeyName must not be empty");
 		Assert.notNull(plaintext, "Plain text must not be null");
+		Assert.notNull(transitContext, "VaultTransitContext must not be null");
 
 		Map<String, String> request = new LinkedHashMap<>();
 
 		request.put("plaintext", Base64Utils.encodeToString(plaintext));
 
-		if (transitRequest != null) {
-			applyTransitOptions(transitRequest, request);
-		}
+		applyTransitOptions(transitContext, request);
 
 		return (String) vaultOperations
 				.write(String.format("%s/encrypt/%s", path, keyName), request)
@@ -180,7 +180,7 @@ public class VaultTransitTemplate implements VaultTransitOperations {
 	public String decrypt(String keyName, String ciphertext) {
 
 		Assert.hasText(keyName, "KeyName must not be empty");
-		Assert.hasText(keyName, "Cipher text must not be empty");
+		Assert.hasText(ciphertext, "Cipher text must not be empty");
 
 		Map<String, String> request = new LinkedHashMap<>();
 
@@ -195,18 +195,17 @@ public class VaultTransitTemplate implements VaultTransitOperations {
 
 	@Override
 	public byte[] decrypt(String keyName, String ciphertext,
-			@Nullable VaultTransitContext transitRequest) {
+			VaultTransitContext transitContext) {
 
 		Assert.hasText(keyName, "KeyName must not be empty");
-		Assert.hasText(keyName, "Cipher text must not be empty");
+		Assert.hasText(ciphertext, "Cipher text must not be empty");
+		Assert.notNull(transitContext, "VaultTransitContext must not be null");
 
 		Map<String, String> request = new LinkedHashMap<>();
 
 		request.put("ciphertext", ciphertext);
 
-		if (transitRequest != null) {
-			applyTransitOptions(transitRequest, request);
-		}
+		applyTransitOptions(transitContext, request);
 
 		String plaintext = (String) vaultOperations
 				.write(String.format("%s/decrypt/%s", path, keyName), request)
@@ -231,34 +230,32 @@ public class VaultTransitTemplate implements VaultTransitOperations {
 
 	@Override
 	public String rewrap(String keyName, String ciphertext,
-			@Nullable VaultTransitContext transitRequest) {
+			VaultTransitContext transitContext) {
 
 		Assert.hasText(keyName, "KeyName must not be empty");
 		Assert.hasText(ciphertext, "Cipher text must not be empty");
+		Assert.notNull(transitContext, "VaultTransitContext must not be null");
 
 		Map<String, String> request = new LinkedHashMap<>();
 
 		request.put("ciphertext", ciphertext);
 
-		if (transitRequest != null) {
-			applyTransitOptions(transitRequest, request);
-		}
+		applyTransitOptions(transitContext, request);
 
 		return (String) vaultOperations
 				.write(String.format("%s/rewrap/%s", path, keyName), request)
 				.getRequiredData().get("ciphertext");
 	}
 
-	private void applyTransitOptions(VaultTransitContext transitRequest,
+	private static void applyTransitOptions(VaultTransitContext context,
 			Map<String, String> request) {
 
-		if (transitRequest.getContext() != null) {
-			request.put("context",
-					Base64Utils.encodeToString(transitRequest.getContext()));
+		if (!ObjectUtils.isEmpty(context.getContext())) {
+			request.put("context", Base64Utils.encodeToString(context.getContext()));
 		}
 
-		if (transitRequest.getNonce() != null) {
-			request.put("nonce", Base64Utils.encodeToString(transitRequest.getNonce()));
+		if (!ObjectUtils.isEmpty(context.getNonce())) {
+			request.put("nonce", Base64Utils.encodeToString(context.getNonce()));
 		}
 	}
 

spring-vault-core/src/main/java/org/springframework/vault/support/VaultTransitContext.java

@@ -15,7 +15,7 @@
  */
 package org.springframework.vault.support;
 
-import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 
 /**
  * Transit backend encryption/decryption/rewrapping context.
@@ -28,15 +28,14 @@ public class VaultTransitContext {
 	 * Empty (default) {@link VaultTransitContext} without a {@literal context} and
 	 * {@literal nonce}.
 	 */
-	private static final VaultTransitContext EMPTY = new VaultTransitContext(null, null);
+	private static final VaultTransitContext EMPTY = new VaultTransitContext(new byte[0],
+			new byte[0]);
 
-	@Nullable
 	private final byte[] context;
 
-	@Nullable
 	private final byte[] nonce;
 
-	VaultTransitContext(@Nullable byte[] context, @Nullable byte[] nonce) {
+	VaultTransitContext(byte[] context, byte[] nonce) {
 		this.context = context;
 		this.nonce = nonce;
 	}
@@ -55,10 +54,31 @@ public class VaultTransitContext {
 		return EMPTY;
 	}
 
+	/**
+	 * Create a {@link VaultTransitContext} given {@code context} bytes.
+	 *
+	 * @param context context bytes, must not be {@literal null}.
+	 * @return a {@link VaultTransitContext} for {@code context}.
+	 * @since 2.0
+	 */
+	public static VaultTransitContext fromContext(byte[] context) {
+		return builder().context(context).build();
+	}
+
+	/**
+	 * Create a {@link VaultTransitContext} given {@code nonce} bytes.
+	 *
+	 * @param nonce nonce bytes, must not be {@literal null}.
+	 * @return a {@link VaultTransitContext} for {@code nonce}.
+	 * @since 2.0
+	 */
+	public static VaultTransitContext fromNonce(byte[] nonce) {
+		return builder().nonce(nonce).build();
+	}
+
 	/**
 	 * @return the key derivation context.
 	 */
-	@Nullable
 	public byte[] getContext() {
 		return context;
 	}
@@ -66,7 +86,6 @@ public class VaultTransitContext {
 	/**
 	 * @return the
 	 */
-	@Nullable
 	public byte[] getNonce() {
 		return nonce;
 	}
@@ -76,11 +95,8 @@ public class VaultTransitContext {
 	 */
 	public static class VaultTransitRequestBuilder {
 
-		@Nullable
-		private byte[] context;
-
-		@Nullable
-		private byte[] nonce;
+		private byte[] context = new byte[0];
+		private byte[] nonce = new byte[0];
 
 		VaultTransitRequestBuilder() {
 		}
@@ -92,7 +108,10 @@ public class VaultTransitContext {
 		 * provided if derivation is enabled.
 		 * @return {@code this} {@link VaultTransitRequestBuilder}.
 		 */
-		public VaultTransitRequestBuilder context(@Nullable byte[] context) {
+		public VaultTransitRequestBuilder context(byte[] context) {
+
+			Assert.notNull(context, "Context must not be null");
+
 			this.context = context;
 			return this;
 		}
@@ -107,7 +126,10 @@ public class VaultTransitContext {
 		 * nonce value is never reused
 		 * @return {@code this} {@link VaultTransitRequestBuilder}.
 		 */
-		public VaultTransitRequestBuilder nonce(@Nullable byte[] nonce) {
+		public VaultTransitRequestBuilder nonce(byte[] nonce) {
+
+			Assert.notNull(nonce, "Nonce must not be null");
+
 			this.nonce = nonce;
 			return this;
 		}

spring-vault-core/src/test/java/org/springframework/vault/support/VaultTransitContextUnitTests.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright 2017 the original author or 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 org.springframework.vault.support;
+
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Unit tests for {@link VaultTransitContext}.
+ *
+ * @author Mark Paluch
+ */
+public class VaultTransitContextUnitTests {
+
+	@Test(expected = IllegalArgumentException.class)
+	public void rejectsNullContext() {
+		VaultTransitContext.fromContext(null);
+	}
+
+	@Test
+	public void createsFromContext() {
+
+		byte[] bytes = new byte[] { 1 };
+
+		VaultTransitContext context = VaultTransitContext.fromContext(bytes);
+
+		assertThat(context.getContext()).isEqualTo(bytes);
+		assertThat(context.getNonce()).isEmpty();
+	}
+
+	@Test(expected = IllegalArgumentException.class)
+	public void rejectsNullNonce() {
+		VaultTransitContext.fromNonce(null);
+	}
+
+	@Test
+	public void createsFromNonce() {
+
+		byte[] bytes = new byte[] { 1 };
+
+		VaultTransitContext context = VaultTransitContext.fromNonce(bytes);
+
+		assertThat(context.getNonce()).isEqualTo(bytes);
+		assertThat(context.getContext()).isEmpty();
+	}
+}