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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.apache.cassandra.cql3.functions.masking;
import java.nio.ByteBuffer;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import javax.annotation.Nullable;
import com.google.common.annotations.VisibleForTesting;
import org.apache.cassandra.cql3.CQL3Type;
import org.apache.cassandra.cql3.functions.ArgumentDeserializer;
import org.apache.cassandra.cql3.functions.Arguments;
import org.apache.cassandra.cql3.functions.FunctionArguments;
import org.apache.cassandra.cql3.functions.FunctionFactory;
import org.apache.cassandra.cql3.functions.FunctionName;
import org.apache.cassandra.cql3.functions.FunctionParameter;
import org.apache.cassandra.cql3.functions.NativeFunction;
import org.apache.cassandra.db.marshal.AbstractType;
import org.apache.cassandra.db.marshal.BytesType;
import org.apache.cassandra.db.marshal.UTF8Type;
import org.apache.cassandra.exceptions.InvalidRequestException;
import org.apache.cassandra.transport.ProtocolVersion;
import org.apache.cassandra.utils.ByteBufferUtil;
/**
* A {@link MaskingFunction} that replaces the specified column value by its hash according to the specified
* algorithm. The available algorithms are those defined by the registered security {@link java.security.Provider}s.
* If no algorithm is passed to the function, the {@link #DEFAULT_ALGORITHM} will be used.
*/
public class HashMaskingFunction extends MaskingFunction
{
public static final String NAME = "hash";
/** The default hashing algorithm to be used if no other algorithm is specified in the call to the function. */
public static final ByteBuffer DEFAULT_ALGORITHM = UTF8Type.instance.decompose("SHA-256");
/**
* All the created digests that we use to generate the hash, so we don't need to get them on every call.
* We use the serialized algorithm as key, so we don't have to deserialize it for getting a cache hit.
*/
private static final Map DIGESTS = new ConcurrentHashMap<>();
private static final AbstractType>[] DEFAULT_ARGUMENTS = {};
private static final AbstractType>[] ARGUMENTS_WITH_ALGORITHM = new AbstractType>[]{ UTF8Type.instance };
private HashMaskingFunction(FunctionName name, AbstractType> inputType, boolean hasAlgorithmArgument)
{
super(name, BytesType.instance, inputType, hasAlgorithmArgument ? ARGUMENTS_WITH_ALGORITHM : DEFAULT_ARGUMENTS);
}
@Override
public Arguments newArguments(ProtocolVersion version)
{
return new FunctionArguments(version,
ArgumentDeserializer.NOOP_DESERIALIZER, // the value to be masked
(v, b) -> messageDigest(b)); // the algorithm, if any
}
@Override
public ByteBuffer execute(Arguments arguments) throws InvalidRequestException
{
ByteBuffer value = arguments.get(0);
if (value == null)
return null;
MessageDigest digest = arguments.get(1);
if (digest == null)
digest = messageDigest(DEFAULT_ALGORITHM);
return HashMaskingFunction.hash(digest, value);
}
@VisibleForTesting
@Nullable
static ByteBuffer hash(MessageDigest digest, ByteBuffer value)
{
if (value == null)
return null;
byte[] hash = digest.digest(ByteBufferUtil.getArray(value));
return BytesType.instance.compose(ByteBuffer.wrap(hash));
}
@VisibleForTesting
static MessageDigest messageDigest(@Nullable ByteBuffer algorithm)
{
ByteBuffer cacheKey = algorithm == null ? DEFAULT_ALGORITHM : algorithm;
MessageDigest digest = DIGESTS.get(cacheKey);
if (digest == null)
{
digest = messageDigest(UTF8Type.instance.compose(cacheKey));
DIGESTS.put(cacheKey.duplicate(), digest);
}
return digest;
}
@VisibleForTesting
static MessageDigest messageDigest(String algorithm)
{
try
{
return MessageDigest.getInstance(algorithm);
}
catch (NoSuchAlgorithmException e)
{
throw new InvalidRequestException("Hash algorithm not found: " + algorithm);
}
}
/** @return a {@link FunctionFactory} to build new {@link HashMaskingFunction}s. */
public static FunctionFactory factory()
{
return new MaskingFunction.Factory(NAME,
FunctionParameter.anyType(false),
FunctionParameter.optional(FunctionParameter.fixed(CQL3Type.Native.TEXT)))
{
@Override
protected NativeFunction doGetOrCreateFunction(List> argTypes, AbstractType> receiverType)
{
switch (argTypes.size())
{
case 1:
return new HashMaskingFunction(name, argTypes.get(0), false);
case 2:
return new HashMaskingFunction(name, argTypes.get(0), true);
default:
throw invalidNumberOfArgumentsException();
}
}
};
}
}
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