/*

  * 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.shiro.crypto.hash;

 import org.apache.shiro.codec.Base64;

 import org.apache.shiro.codec.CodecException;

 import org.apache.shiro.codec.CodecSupport;

 import org.apache.shiro.codec.Hex;

 import org.apache.shiro.crypto.UnknownAlgorithmException;

 import java.io.Serializable;

 import java.security.MessageDigest;

 import java.security.NoSuchAlgorithmException;

 import java.util.Arrays;

 /**

  * Provides a base for all Shiro Hash algorithms with support for salts and multiple hash iterations.

  * <p/>

  * Read

  * <a href="http://www.owasp.org/index.php/Hashing_Java" target="blank">http://www.owasp.org/index.php/Hashing_Java</a>

  * for a good article on the benefits of hashing, including what a 'salt' is as well as why it and multiple hash

  * iterations can be useful.

  * <p/>

  * This class and its subclasses support hashing with additional capabilities of salting and multiple iterations via

  * overloaded constructors.

  *

  * @since 0.9

  * @deprecated in Shiro 1.1 in favor of using the concrete {@link SimpleHash} implementation directly.

  */

 @Deprecated

 public abstract class AbstractHash extends CodecSupport implements Hash, Serializable {

     /**

      * The hashed data

      */

     private byte[] bytes = null;

     /**

      * Cached value of the {@link #toHex() toHex()} call so multiple calls won't incur repeated overhead.

      */

     private transient String hexEncoded = null;

     /**

      * Cached value of the {@link #toBase64() toBase64()} call so multiple calls won't incur repeated overhead.

      */

     private transient String base64Encoded = null;

     /**

      * Creates an new instance without any of its properties set (no hashing is performed).

      * <p/>

      * Because all constructors in this class (except this one) hash the {@code source} constructor argument, this

      * default, no-arg constructor is useful in scenarios when you have a byte array that you know is already hashed and

      * just want to set the bytes in their raw form directly on an instance.  After instantiating the instance with

      * this default, no-arg constructor, you can then immediately call {@link #setBytes setBytes} to have a

      * fully-initialized instance.

      */

     public AbstractHash() {

     }

     /**

      * Creates a hash of the specified {@code source} with no {@code salt} using a single hash iteration.

      * <p/>

      * It is a convenience constructor that merely executes <code>this( source, null, 1);</code>.

      * <p/>

      * Please see the

      * {@link #AbstractHash(Object source, Object salt, int numIterations) AbstractHash(Object,Object,int)}

      * constructor for the types of Objects that may be passed into this constructor, as well as how to support further

      * types.

      *

      * @param source the object to be hashed.

      * @throws CodecException if the specified {@code source} cannot be converted into a byte array (byte[]).

      */

     public AbstractHash(Object source) throws CodecException {

         this(source, null, 1);

     }

     /**

      * Creates a hash of the specified {@code source} using the given {@code salt} using a single hash iteration.

      * <p/>

      * It is a convenience constructor that merely executes <code>this( source, salt, 1);</code>.

      * <p/>

      * Please see the

      * {@link #AbstractHash(Object source, Object salt, int numIterations) AbstractHash(Object,Object,int)}

      * constructor for the types of Objects that may be passed into this constructor, as well as how to support further

      * types.

      *

      * @param source the source object to be hashed.

      * @param salt   the salt to use for the hash

      * @throws CodecException if either constructor argument cannot be converted into a byte array.

      */

     public AbstractHash(Object source, Object salt) throws CodecException {

         this(source, salt, 1);

     }

     /**

      * Creates a hash of the specified {@code source} using the given {@code salt} a total of

      * {@code hashIterations} times.

      * <p/>

      * By default, this class only supports Object method arguments of

      * type {@code byte[]}, {@code char[]}, {@link String}, {@link java.io.File File}, or

      * {@link java.io.InputStream InputStream}.  If either argument is anything other than these

      * types a {@link org.apache.shiro.codec.CodecException CodecException} will be thrown.

      * <p/>

      * If you want to be able to hash other object types, or use other salt types, you need to override the

      * {@link #toBytes(Object) toBytes(Object)} method to support those specific types.  Your other option is to

      * convert your arguments to one of the default three supported types first before passing them in to this

      * constructor}.

      *

      * @param source         the source object to be hashed.

      * @param salt           the salt to use for the hash

      * @param hashIterations the number of times the {@code source} argument hashed for attack resiliency.

      * @throws CodecException if either Object constructor argument cannot be converted into a byte array.

      */

     public AbstractHash(Object source, Object salt, int hashIterations) throws CodecException {

         byte[] sourceBytes = toBytes(source);

         byte[] saltBytes = null;

         if (salt != null) {

             saltBytes = toBytes(salt);

         }

         byte[] hashedBytes = hash(sourceBytes, saltBytes, hashIterations);

         setBytes(hashedBytes);

     }

     /**

      * Implemented by subclasses, this specifies the {@link MessageDigest MessageDigest} algorithm name 

      * to use when performing the hash.

      *

      * @return the {@link MessageDigest MessageDigest} algorithm name to use when performing the hash.

      */

     public abstract String getAlgorithmName();

     public byte[] getBytes() {

         return this.bytes;

     }

     /**

      * Sets the raw bytes stored by this hash instance.

      * <p/>

      * The bytes are kept in raw form - they will not be hashed/changed.  This is primarily a utility method for

      * constructing a Hash instance when the hashed value is already known.

      *

      * @param alreadyHashedBytes the raw already-hashed bytes to store in this instance.

      */

     public void setBytes(byte[] alreadyHashedBytes) {

         this.bytes = alreadyHashedBytes;

         this.hexEncoded = null;

         this.base64Encoded = null;

     }

     /**

      * Returns the JDK MessageDigest instance to use for executing the hash.

      *

      * @param algorithmName the algorithm to use for the hash, provided by subclasses.

      * @return the MessageDigest object for the specified {@code algorithm}.

      * @throws UnknownAlgorithmException if the specified algorithm name is not available.

      */

     protected MessageDigest getDigest(String algorithmName) throws UnknownAlgorithmException {

         try {

             return MessageDigest.getInstance(algorithmName);

         } catch (NoSuchAlgorithmException e) {

             String msg = "No native '" + algorithmName + "' MessageDigest instance available on the current JVM.";

             throw new UnknownAlgorithmException(msg, e);

         }

     }

     /**

      * Hashes the specified byte array without a salt for a single iteration.

      *

      * @param bytes the bytes to hash.

      * @return the hashed bytes.

      */

     protected byte[] hash(byte[] bytes) {

         return hash(bytes, null, 1);

     }

     /**

      * Hashes the specified byte array using the given {@code salt} for a single iteration.

      *

      * @param bytes the bytes to hash

      * @param salt  the salt to use for the initial hash

      * @return the hashed bytes

      */

     protected byte[] hash(byte[] bytes, byte[] salt) {

         return hash(bytes, salt, 1);

     }

     /**

      * Hashes the specified byte array using the given {@code salt} for the specified number of iterations.

      *

      * @param bytes          the bytes to hash

      * @param salt           the salt to use for the initial hash

      * @param hashIterations the number of times the the {@code bytes} will be hashed (for attack resiliency).

      * @return the hashed bytes.

      * @throws UnknownAlgorithmException if the {@link #getAlgorithmName() algorithmName} is not available.

      */

     protected byte[] hash(byte[] bytes, byte[] salt, int hashIterations) throws UnknownAlgorithmException {

         MessageDigest digest = getDigest(getAlgorithmName());

         if (salt != null) {

             digest.reset();

             digest.update(salt);

         }

         byte[] hashed = digest.digest(bytes);

         int iterations = hashIterations - 1; //already hashed once above

         //iterate remaining number:

         for (int i = 0; i < iterations; i++) {

             digest.reset();

             hashed = digest.digest(hashed);

         }

         return hashed;

     }

     /**

      * Returns a hex-encoded string of the underlying {@link #getBytes byte array}.

      * <p/>

      * This implementation caches the resulting hex string so multiple calls to this method remain efficient.

      * However, calling {@link #setBytes setBytes} will null the cached value, forcing it to be recalculated the

      * next time this method is called.

      *

      * @return a hex-encoded string of the underlying {@link #getBytes byte array}.

      */

     public String toHex() {

         if (this.hexEncoded == null) {

             this.hexEncoded = Hex.encodeToString(getBytes());

         }

         return this.hexEncoded;

     }

     /**

      * Returns a Base64-encoded string of the underlying {@link #getBytes byte array}.

      * <p/>

      * This implementation caches the resulting Base64 string so multiple calls to this method remain efficient.

      * However, calling {@link #setBytes setBytes} will null the cached value, forcing it to be recalculated the

      * next time this method is called.

      *

      * @return a Base64-encoded string of the underlying {@link #getBytes byte array}.

      */

     public String toBase64() {

         if (this.base64Encoded == null) {

             //cache result in case this method is called multiple times.

             this.base64Encoded = Base64.encodeToString(getBytes());

         }

         return this.base64Encoded;

     }

     /**

      * Simple implementation that merely returns {@link #toHex() toHex()}.

      *

      * @return the {@link #toHex() toHex()} value.

      */

     public String toString() {

         return toHex();

     }

     /**

      * Returns {@code true} if the specified object is a Hash and its {@link #getBytes byte array} is identical to

      * this Hash's byte array, {@code false} otherwise.

      *

      * @param o the object (Hash) to check for equality.

      * @return {@code true} if the specified object is a Hash and its {@link #getBytes byte array} is identical to

      *         this Hash's byte array, {@code false} otherwise.

      */

     public boolean equals(Object o) {

         if (o instanceof Hash) {

             Hash other = (Hash) o;

             return Arrays.equals(getBytes(), other.getBytes());

         }

         return false;

     }

     /**

      * Simply returns toHex().hashCode();

      *

      * @return toHex().hashCode()

      */

     public int hashCode() {

         if (this.bytes == null || this.bytes.length == 0) {

             return 0;

         }

         return Arrays.hashCode(this.bytes);

     }

     private static void printMainUsage(Class<? extends AbstractHash> clazz, String type) {

         System.out.println("Prints an " + type + " hash value.");

         System.out.println("Usage: java " + clazz.getName() + " [-base64] [-salt <saltValue>] [-times <N>] <valueToHash>");

         System.out.println("Options:");

         System.out.println("\t-base64\t\tPrints the hash value as a base64 String instead of the default hex.");

         System.out.println("\t-salt\t\tSalts the hash with the specified <saltValue>");

         System.out.println("\t-times\t\tHashes the input <N> number of times");

     }

     private static boolean isReserved(String arg) {

         return "-base64".equals(arg) || "-times".equals(arg) || "-salt".equals(arg);

     }

     static int doMain(Class<? extends AbstractHash> clazz, String[] args) {

         String simple = clazz.getSimpleName();

         int index = simple.indexOf("Hash");

         String type = simple.substring(0, index).toUpperCase();

         if (args == null || args.length < 1 || args.length > 7) {

             printMainUsage(clazz, type);

             return -1;

         }

         boolean hex = true;

         String salt = null;

         int times = 1;

         String text = args[args.length - 1];

         for (int i = 0; i < args.length; i++) {

             String arg = args[i];

             if (arg.equals("-base64")) {

                 hex = false;

             } else if (arg.equals("-salt")) {

                 if ((i + 1) >= (args.length - 1)) {

                     String msg = "Salt argument must be followed by a salt value.  The final argument is " +

                             "reserved for the value to hash.";

                     System.out.println(msg);

                     printMainUsage(clazz, type);

                     return -1;

                 }

                 salt = args[i + 1];

             } else if (arg.equals("-times")) {

                 if ((i + 1) >= (args.length - 1)) {

                     String msg = "Times argument must be followed by an integer value.  The final argument is " +

                             "reserved for the value to hash";

                     System.out.println(msg);

                     printMainUsage(clazz, type);

                     return -1;

                 }

                 try {

                     times = Integer.valueOf(args[i + 1]);

                 } catch (NumberFormatException e) {

                     String msg = "Times argument must be followed by an integer value.";

                     System.out.println(msg);

                     printMainUsage(clazz, type);

                     return -1;

                 }

             }

         }

         Hash hash = new Md2Hash(text, salt, times);

         String hashed = hex ? hash.toHex() : hash.toBase64();

         System.out.print(hex ? "Hex: " : "Base64: ");

         System.out.println(hashed);

         return 0;

     }

 }