com.amazonaws.encryptionsdk.MasterKey Maven / Gradle / Ivy

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/*
 * Copyright 2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"). You may not use this file except
 * in compliance with the License. A copy of the License is located at
 * 
 * http://aws.amazon.com/apache2.0
 * 
 * or in the "license" file accompanying this file. This file 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.amazonaws.encryptionsdk;

import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Objects;

import com.amazonaws.encryptionsdk.exception.NoSuchMasterKeyException;
import com.amazonaws.encryptionsdk.exception.UnsupportedProviderException;

/**
 * Represents the cryptographic key used to protect the {@link DataKey} (which, in turn, protects
 * the data).
 *
 * All MasterKeys extend {@link MasterKeyProvider} because they are all capable of providing exactly
 * themselves. This simplifies implementation when only a single {@link MasterKey} is used and/or
 * expected.
 *
 * @param 
 *            the concrete type of the {@link MasterKey}
 */
public abstract class MasterKey> extends MasterKeyProvider {
    public abstract String getProviderId();

    /**
     * Equivalent to calling {@link #getProviderId()}.
     */
    @Override
    public String getDefaultProviderId() {
        return getProviderId();
    }

    public abstract String getKeyId();

    /**
     * Generates a new {@link DataKey} which is protected by this {@link MasterKey} for use with
     * {@code algorithm} and associated with the provided {@code encryptionContext}.
     */
    public abstract DataKey generateDataKey(CryptoAlgorithm algorithm, Map encryptionContext);

    /**
     * Returns a new copy of the provided {@code dataKey} which is protected by this
     * {@link MasterKey} for use with {@code algorithm} and associated with the provided
     * {@code encryptionContext}.
     */
    public abstract DataKey encryptDataKey(CryptoAlgorithm algorithm, Map encryptionContext,
            DataKey dataKey);

    /**
     * Returns {@code true} if and only if {@code provider} equals {@link #getProviderId()}.
     */
    @Override
    public boolean canProvide(final String provider) {
        return getProviderId().equals(provider);
    }

    /**
     * Returns {@code this} if {@code provider} and {@code keyId} match {@code this}. Otherwise,
     * throws an appropriate exception.
     */
    @SuppressWarnings("unchecked")
    @Override
    public K getMasterKey(final String provider, final String keyId) throws UnsupportedProviderException,
            NoSuchMasterKeyException {
        if (!canProvide(provider)) {
            throw new UnsupportedProviderException("MasterKeys can only provide themselves. Requested "
                    + buildName(provider, keyId) + " but only " + toString() + " is available");
        }
        if (!getKeyId().equals(keyId)) {
            throw new NoSuchMasterKeyException("MasterKeys can only provide themselves. Requested "
                    + buildName(provider, keyId) + " but only " + toString() + " is available");
        }
        return (K) this;
    }

    @Override
    public String toString() {
        return buildName(getProviderId(), getKeyId());
    }

    /**
     * Returns a list of length {@code 1} containing {@code this}.
     */
    @SuppressWarnings("unchecked")
    @Override
    public List getMasterKeysForEncryption(final MasterKeyRequest request) {
        return (List) Collections.singletonList(this);
    }

    private static String buildName(final String provider, final String keyId) {
        return String.format("%s://%s", provider, keyId);
    }

    /**
     * Two {@link MasterKey}s are equal if they are instances of the exact same class and
     * their values for {@code keyId}, {@code providerId}, and {@code defaultProviderId} are equal.
     */
    @Override
    public boolean equals(final Object obj) {
        if (obj == null) {
            return false;
        }
        if (this == obj) {
            return true;
        }
        if (!obj.getClass().equals(getClass())) {
            return false;
        }
        final MasterKey mk = (MasterKey) obj;
        return Objects.equals(getKeyId(), mk.getKeyId()) &&
                Objects.equals(getProviderId(), mk.getProviderId()) &&
                Objects.equals(getDefaultProviderId(), mk.getDefaultProviderId());
    }

    @Override
    public int hashCode() {
        return Objects.hash(getKeyId(), getProviderId(), getDefaultProviderId());
    }
}