com.google.crypto.tink.integration.awskms.AwsKmsClient.java Source code

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Here is the source code for com.google.crypto.tink.integration.awskms.AwsKmsClient.java

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// Copyright 2017 Google Inc.
//
// 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 com.google.crypto.tink.integration.awskms;

import com.amazonaws.AmazonServiceException;
import com.amazonaws.auth.AWSCredentialsProvider;
import com.amazonaws.auth.DefaultAWSCredentialsProviderChain;
import com.amazonaws.auth.PropertiesFileCredentialsProvider;
import com.amazonaws.regions.Regions;
import com.amazonaws.services.kms.AWSKMS;
import com.amazonaws.services.kms.AWSKMSClientBuilder;
import com.google.auto.service.AutoService;
import com.google.crypto.tink.Aead;
import com.google.crypto.tink.KmsClient;
import com.google.crypto.tink.subtle.Validators;
import java.security.GeneralSecurityException;

/**
 * An implementation of {@link KmsClient} for <a href="https://aws.amazon.com/kms/">AWS KMS</a>.
 *
 * @since 1.0.0
 */
@AutoService(KmsClient.class)
public final class AwsKmsClient implements KmsClient {
    /** The prefix of all keys stored in AWS KMS. */
    public static final String PREFIX = "aws-kms://";

    private AWSKMS client;
    private String keyUri;

    /** Constructs a generic AwsKmsClient that is not bound to any specific key. */
    public AwsKmsClient() {
    }

    /** Constructs a specific AwsKmsClient that is bound to a single key identified by {@code uri}. */
    public AwsKmsClient(String uri) {
        if (!uri.toLowerCase().startsWith(PREFIX)) {
            throw new IllegalArgumentException("key URI must starts with " + PREFIX);
        }
        this.keyUri = uri;
    }

    /**
     * @return @return true either if this client is a generic one and uri starts with {@link
     *     AwsKmsClient#PREFIX}, or the client is a specific one that is bound to the key identified
     *     by {@code uri}.
     */
    @Override
    public boolean doesSupport(String uri) {
        if (this.keyUri != null && this.keyUri.equals(uri)) {
            return true;
        }
        return this.keyUri == null && uri.toLowerCase().startsWith(PREFIX);
    }

    /**
     * Loads AWS credentials from a properties file.
     *
     * <p>The AWS access key ID is expected to be in the <code>accessKey</code> property and the AWS
     * secret key is expected to be in the <code>secretKey</code> property.
     *
     * @throws GeneralSecurityException if the client initialization fails
     */
    @Override
    public KmsClient withCredentials(String credentialPath) throws GeneralSecurityException {
        try {
            if (credentialPath == null) {
                return withDefaultCredentials();
            }
            return withCredentialsProvider(new PropertiesFileCredentialsProvider(credentialPath));
        } catch (AmazonServiceException e) {
            throw new GeneralSecurityException("cannot load credentials", e);
        }
    }

    /**
     * Loads default AWS credentials.
     *
     * <p>AWS credentials provider chain that looks for credentials in this order:
     *
     * <ul>
     *   <li>Environment Variables - AWS_ACCESS_KEY_ID and AWS_SECRET_KEY
     *   <li>Java System Properties - aws.accessKeyId and aws.secretKey
     *   <li>Credential profiles file at the default location (~/.aws/credentials)
     *   <li>Instance profile credentials delivered through the Amazon EC2 metadata service
     * </ul>
     *
     * @throws GeneralSecurityException if the client initialization fails
     */
    @Override
    public KmsClient withDefaultCredentials() throws GeneralSecurityException {
        try {
            return withCredentialsProvider(new DefaultAWSCredentialsProviderChain());
        } catch (AmazonServiceException e) {
            throw new GeneralSecurityException("cannot load default credentials", e);
        }
    }

    /** Loads AWS credentials from a provider. */
    public KmsClient withCredentialsProvider(AWSCredentialsProvider provider) throws GeneralSecurityException {
        try {
            String[] tokens = this.keyUri.split(":");
            this.client = AWSKMSClientBuilder.standard().withCredentials(provider)
                    .withRegion(Regions.fromName(tokens[4])).build();
            return this;
        } catch (AmazonServiceException e) {
            throw new GeneralSecurityException("cannot load credentials from provider", e);
        }
    }

    @Override
    public Aead getAead(String uri) throws GeneralSecurityException {
        if (this.keyUri != null && !this.keyUri.equals(uri)) {
            throw new GeneralSecurityException(
                    String.format("this client is bound to %s, cannot load keys bound to %s", this.keyUri, uri));
        }
        return new AwsKmsAead(client, Validators.validateKmsKeyUriAndRemovePrefix(PREFIX, uri));
    }
}