Introduce Client side S3EncryptionClient

docs/src/main/asciidoc/s3.adoc

@@ -127,6 +127,88 @@ try (OutputStream outputStream = s3Resource.getOutputStream()) {
 }
 ----
 
+=== S3 Client Side Encryption
+
+AWS offers encryption library which is integrated inside of S3 Client called https://docs.aws.amazon.com/amazon-s3-encryption-client/latest/developerguide/what-is-s3-encryption-client.html [S3EncryptionClient].
+With encryption client you are going to encrypt your files before sending them to S3 bucket.
+
+To autoconfigure Encryption Client simply add the following dependency.
+
+[source,xml]
+----
+<dependency>
+	<groupId>software.amazon.encryption.s3</groupId>
+	<artifactId>amazon-s3-encryption-client-java</artifactId>
+</dependency>
+----
+
+
+We are supporting 3 types of encryption.
+
+1. To configure encryption via KMS key specify 'spring.cloud.aws.s3.encryption.keyId' with KMS key arn and this key will be used to encrypt your files.
+
+Also, following dependency is required.
+[source,xml]
+----
+<dependency>
+ 	<groupId>software.amazon.awssdk</groupId>
+	<artifactId>kms</artifactId>
+ 	<optional>true</optional>
+ </dependency>
+----
+
+
+2. Asymmetric encryption is possible via RSA to enable it you will have to implement 'io.awspring.cloud.autoconfigure.s3.S3RsaProvider'
+
+!Note you will have to manage storing private and public keys yourself otherwise you won't be able to decrypt the data later.
+Example of simple RSAProvider:
+
+[source,java,indent=0]
+----
+import io.awspring.cloud.autoconfigure.s3.S3RsaProvider;
+import java.security.KeyPair;
+import java.security.KeyPairGenerator;
+
+public class MyRsaProvider implements S3RsaProvider {
+	@Override
+	public KeyPair generateKeyPair() {
+		try {
+			// fetch key pair from secure location such as Secrets Manager
+			// access to KeyPair is required to decrypt objects when fetching, so it is advised to keep them stored securely
+		}
+		catch (Exception e) {
+			return null;
+		}
+	}
+}
+----
+
+3. Last option is if you want to use symmetric algorithm, this is possible via `io.awspring.cloud.autoconfigure.s3.S3AesProvider`
+
+!Note you will have to manage storing storing private key!
+Example of simple AESProvider:
+
+[source,java,indent=0]
+----
+import io.awspring.cloud.autoconfigure.s3.S3AesProvider;
+import javax.crypto.KeyGenerator;
+import javax.crypto.SecretKey;
+
+public class MyAesProvider implements S3AesProvider {
+	@Override
+	public SecretKey generateSecretKey() {
+		try {
+			// fetch secret key from secure location such as Secrets Manager
+        	// access to secret key is required to decrypt objects when fetching, so it is advised to keep them stored securely
+		}
+		catch (Exception e) {
+			return null;
+		}
+	}
+}
+----
+
+
 ==== S3 Output Stream
 
 Under the hood by default `S3Resource` uses a `io.awspring.cloud.s3.InMemoryBufferingS3OutputStream`. When data is written to the resource, is gets sent to S3 using multipart upload.

spring-cloud-aws-autoconfigure/pom.xml

@@ -166,5 +166,15 @@
 			<artifactId>sts</artifactId>
 			<optional>true</optional>
 		</dependency>
+		<dependency>
+			<groupId>software.amazon.awssdk</groupId>
+			<artifactId>kms</artifactId>
+			<optional>true</optional>
+		</dependency>
+		<dependency>
+			<groupId>software.amazon.encryption.s3</groupId>
+			<artifactId>amazon-s3-encryption-client-java</artifactId>
+			<optional>true</optional>
+		</dependency>
 	</dependencies>
 </project>

spring-cloud-aws-autoconfigure/src/main/java/io/awspring/cloud/autoconfigure/s3/S3AesProvider.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2013-2024 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
+ *
+ *      https://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.awspring.cloud.autoconfigure.s3;
+
+import javax.crypto.SecretKey;
+
+/**
+ * Interface for providing {@link SecretKey} when configuring {@link software.amazon.encryption.s3.S3EncryptionClient}.
+ * Required when encrypting files server side with AES.
+ * Secret Key should be stored in secure storage, for example AWS Secrets Manager.
+ * @author Matej Nedic
+ * @since 3.3.0
+ */
+public interface S3AesProvider {
+
+	/**
+	 * Provides SecretKey that will be used to configure {@link software.amazon.encryption.s3.S3EncryptionClient}.
+	 * Advised to fetch and return SecretKey in this method from Secured Storage.
+	 * @return KeyPair that will be used for encryption/decryption.
+	 */
+	SecretKey generateSecretKey();
+}

spring-cloud-aws-autoconfigure/src/main/java/io/awspring/cloud/autoconfigure/s3/S3AutoConfiguration.java

@@ -35,26 +35,28 @@
 import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.boot.autoconfigure.AutoConfiguration;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
-import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
-import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
-import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
-import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.boot.autoconfigure.condition.*;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
+import org.springframework.boot.context.properties.PropertyMapper;
 import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Conditional;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
 import org.springframework.util.ClassUtils;
+import org.springframework.util.StringUtils;
 import software.amazon.awssdk.auth.credentials.AwsCredentialsProvider;
 import software.amazon.awssdk.regions.providers.AwsRegionProvider;
 import software.amazon.awssdk.s3accessgrants.plugin.S3AccessGrantsPlugin;
 import software.amazon.awssdk.services.s3.S3Client;
 import software.amazon.awssdk.services.s3.S3ClientBuilder;
 import software.amazon.awssdk.services.s3.presigner.S3Presigner;
+import software.amazon.encryption.s3.S3EncryptionClient;
 
 /**
  * {@link EnableAutoConfiguration} for {@link S3Client} and {@link S3ProtocolResolver}.
  *
  * @author Maciej Walkowiak
+ * @author Matej Nedic
  */
 @AutoConfiguration
 @ConditionalOnClass({ S3Client.class, S3OutputStreamProvider.class })
@@ -85,6 +87,7 @@ S3ClientBuilder s3ClientBuilder(AwsClientBuilderConfigurer awsClientBuilderConfi
 					.enableFallback(properties.getPlugin().getEnableFallback()).build();
 			builder.addPlugin(s3AccessGrantsPlugin);
 		}
+
 		Optional.ofNullable(this.properties.getCrossRegionEnabled()).ifPresent(builder::crossRegionAccessEnabled);
 
 		builder.serviceConfiguration(this.properties.toS3Configuration());
@@ -118,13 +121,72 @@ else if (awsProperties.getEndpoint() != null) {
 		Optional.ofNullable(awsProperties.getDualstackEnabled()).ifPresent(builder::dualstackEnabled);
 		return builder.build();
 	}
+	@Conditional(S3EncryptionConditional.class)
+	@ConditionalOnClass(name = "software.amazon.encryption.s3.S3EncryptionClient")
+	@Configuration
+	public static class S3EncryptionConfiguration {
+
+		@Bean
+		@ConditionalOnMissingBean
+		public static S3Client s3EncryptionClient(S3EncryptionClient.Builder s3EncryptionBuilder, S3ClientBuilder s3ClientBuilder) {
+			s3EncryptionBuilder.wrappedClient(s3ClientBuilder.build());
+			return s3EncryptionBuilder.build();
+		}
+
+		@Bean
+		@ConditionalOnMissingBean
+		public static S3EncryptionClient.Builder s3EncrpytionClientBuilder(S3Properties properties,
+				AwsClientBuilderConfigurer awsClientBuilderConfigurer,
+				ObjectProvider<AwsClientCustomizer<S3EncryptionClient.Builder>> configurer,
+				ObjectProvider<AwsConnectionDetails> connectionDetails,
+				ObjectProvider<S3EncryptionClientCustomizer> s3ClientCustomizers,
+				ObjectProvider<AwsSyncClientCustomizer> awsSyncClientCustomizers,
+				ObjectProvider<S3RsaProvider> rsaProvider, ObjectProvider<S3AesProvider> aesProvider) {
+			S3EncryptionClient.Builder builder = awsClientBuilderConfigurer.configureSyncClient(
+					S3EncryptionClient.builder(), properties, connectionDetails.getIfAvailable(),
+					configurer.getIfAvailable(), s3ClientCustomizers.orderedStream(),
+					awsSyncClientCustomizers.orderedStream());
+
+			Optional.ofNullable(properties.getCrossRegionEnabled()).ifPresent(builder::crossRegionAccessEnabled);
+			builder.serviceConfiguration(properties.toS3Configuration());
+
+			configureEncryptionProperties(properties, rsaProvider, aesProvider, builder);
+			return builder;
+		}
+
+		private static void configureEncryptionProperties(S3Properties properties,
+				ObjectProvider<S3RsaProvider> rsaProvider, ObjectProvider<S3AesProvider> aesProvider,
+				S3EncryptionClient.Builder builder) {
+			PropertyMapper propertyMapper = PropertyMapper.get();
+			var encryptionProperties = properties.getEncryption();
+
+			propertyMapper.from(encryptionProperties::isEnableDelayedAuthenticationMode)
+					.to(builder::enableDelayedAuthenticationMode);
+			propertyMapper.from(encryptionProperties::isEnableLegacyUnauthenticatedModes)
+					.to(builder::enableLegacyUnauthenticatedModes);
+			propertyMapper.from(encryptionProperties::isEnableMultipartPutObject).to(builder::enableMultipartPutObject);
+
+			if (!StringUtils.hasText(properties.getEncryption().getKeyId())) {
+				if (aesProvider.getIfAvailable() != null) {
+					builder.aesKey(aesProvider.getObject().generateSecretKey());
+				}
+				else {
+					builder.rsaKeyPair(rsaProvider.getObject().generateKeyPair());
+				}
+			}
+			else {
+				propertyMapper.from(encryptionProperties::getKeyId).to(builder::kmsKeyId);
+			}
+		}
+	}
 
 	@Bean
 	@ConditionalOnMissingBean
 	S3Client s3Client(S3ClientBuilder s3ClientBuilder) {
 		return s3ClientBuilder.build();
 	}
 
+
 	@Configuration
 	@ConditionalOnClass(ObjectMapper.class)
 	static class Jackson2JsonS3ObjectConverterConfiguration {
@@ -143,5 +205,4 @@ S3OutputStreamProvider inMemoryBufferingS3StreamProvider(S3Client s3Client,
 		return new InMemoryBufferingS3OutputStreamProvider(s3Client,
 				contentTypeResolver.orElseGet(PropertiesS3ObjectContentTypeResolver::new));
 	}
-
 }

spring-cloud-aws-autoconfigure/src/main/java/io/awspring/cloud/autoconfigure/s3/S3EncryptionClientCustomizer.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2013-2024 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
+ *
+ *      https://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.awspring.cloud.autoconfigure.s3;
+
+import io.awspring.cloud.autoconfigure.AwsClientCustomizer;
+import software.amazon.encryption.s3.S3EncryptionClient;
+
+/**
+ * Callback interface that can be used to customize a {@link S3EncryptionClient.Builder}.
+ *
+ * @author Matej Nedic
+ * @since 3.3.0
+ */
+@FunctionalInterface
+public interface S3EncryptionClientCustomizer extends AwsClientCustomizer<S3EncryptionClient.Builder> {
+}

spring-cloud-aws-autoconfigure/src/main/java/io/awspring/cloud/autoconfigure/s3/S3EncryptionConditional.java

@@ -0,0 +1,29 @@
+package io.awspring.cloud.autoconfigure.s3;
+
+import org.springframework.boot.autoconfigure.condition.AnyNestedCondition;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+
+/**
+ * Conditional for creating {@link software.amazon.encryption.s3.S3EncryptionClient}.
+ * Will only create S3EncryptionClient if one of following is true.
+ * @author Matej Nedic
+ * @since 3.3.0
+ */
+public class S3EncryptionConditional extends AnyNestedCondition {
+	public S3EncryptionConditional() {
+		super(ConfigurationPhase.REGISTER_BEAN);
+	}
+
+	@ConditionalOnBean(S3RsaProvider.class)
+	static class RSAProviderCondition {
+	}
+
+	@ConditionalOnBean(S3AesProvider.class)
+	static class AESProviderCondition {
+	}
+
+	@ConditionalOnProperty(name = "spring.cloud.aws.s3.encryption.keyId")
+	static class KmsKeyProperty {
+	}
+}

spring-cloud-aws-autoconfigure/src/main/java/io/awspring/cloud/autoconfigure/s3/S3RsaProvider.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2013-2024 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
+ *
+ *      https://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.awspring.cloud.autoconfigure.s3;
+
+import java.security.KeyPair;
+
+
+/**
+ * Interface for providing {@link KeyPair} when configuring {@link software.amazon.encryption.s3.S3EncryptionClient}.
+ * Required for encrypting/decrypting files server side with RSA.
+ * Key pair should be stored in secure storage, for example AWS Secrets Manager.
+ * @author Matej Nedic
+ * @since 3.3.0
+ */
+public interface S3RsaProvider {
+
+	/**
+	 * Provides KeyPair that will be used to configure {@link software.amazon.encryption.s3.S3EncryptionClient}.
+	 * Advised to fetch and return KeyPair in this method from Secured Storage.
+	 * @return KeyPair that will be used for encryption/decryption.
+	 */
+	KeyPair generateKeyPair();
+}