/* ====================================================================
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for additional information regarding copyright ownership.
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The ASF licenses this file to You under the Apache License, Version 2.0
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(the "License"); you may not use this file except in compliance with
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the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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==================================================================== */
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using System;
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using System.Collections.Generic;
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using System.Text;
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using System.IO;
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using HH.WMS.Utils.NPOI.POIFS.FileSystem;
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using HH.WMS.Utils.NPOI.Util;
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using HH.WMS.Utils.NPOI;
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using System.Security;
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using System.Security.Cryptography;
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namespace HH.WMS.Utils.NPOI.POIFS.Crypt
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{
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public abstract class Decryptor
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{
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public static string DEFAULT_PASSWORD = "VelvetSweatshop";
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public abstract Stream GetDataStream(DirectoryNode dir);
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public abstract bool VerifyPassword(string password);
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public static Decryptor GetInstance(EncryptionInfo info)
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{
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int major = info.VersionMajor;
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int minor = info.VersionMinor;
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if (major == 4 && minor == 4)
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return new AgileDecryptor(info);
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else if (minor == 2 && (major == 3 || major == 4))
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return new EcmaDecryptor(info);
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else
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throw new EncryptedDocumentException("Unsupported version");
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}
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public Stream GetDataStream(NPOIFSFileSystem fs)
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{
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return GetDataStream(fs.Root);
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}
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public Stream GetDataStream(POIFSFileSystem fs)
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{
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return GetDataStream(fs.Root);
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}
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protected static int GetBlockSize(int algorithm)
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{
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switch (algorithm)
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{
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case EncryptionHeader.ALGORITHM_AES_128:
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return 16;
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case EncryptionHeader.ALGORITHM_AES_192:
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return 24;
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case EncryptionHeader.ALGORITHM_AES_256:
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return 32;
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}
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throw new EncryptedDocumentException("Unknown block size");
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}
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protected byte[] HashPassword(EncryptionInfo info, string password)
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{
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HashAlgorithm sha1 = HashAlgorithm.Create("SHA1");
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byte[] bytes;
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try
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{
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bytes = Encoding.Unicode.GetBytes(password); //bytes = password.getBytes("UTF-16LE");
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}
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catch (CryptographicUnexpectedOperationException)
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{
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throw new EncryptedDocumentException("UTF16 not supported");
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}
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//sha1.ComputeHash(info.GetVerifier().Salt);
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byte[] salt = info.Verifier.Salt;
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byte[] temp = new byte[salt.Length + bytes.Length];
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Array.Copy(salt, temp, salt.Length);
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Array.Copy(bytes, 0, temp, salt.Length, bytes.Length);
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byte[] hash = sha1.ComputeHash(temp);
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byte[] iterator = new byte[4];
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temp = new byte[24];
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for (int i = 0; i < info.Verifier.SpinCount; i++)
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{
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//sha1.Clear();
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LittleEndian.PutInt(iterator, i);
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//sha1.iterator; //sha1.update(iterator);
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Array.Copy(iterator, temp, iterator.Length);
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Array.Copy(hash, 0, temp, iterator.Length, hash.Length);
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hash = sha1.ComputeHash(temp);
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}
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return hash;
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}
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protected byte[] Decrypt(SymmetricAlgorithm cipher,byte[] encryptBytes)
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{
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byte[] decryptBytes = new byte[0];
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using (MemoryStream fStream = new MemoryStream(encryptBytes))
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{
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using (CryptoStream cStream = new CryptoStream(fStream, cipher.CreateDecryptor(cipher.Key, cipher.IV),
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CryptoStreamMode.Read))
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{
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using (MemoryStream destMs = new MemoryStream())
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{
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byte[] buffer = new byte[100];
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int readLen;
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while ((readLen = cStream.Read(buffer, 0, 100)) > 0)
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destMs.Write(buffer, 0, readLen);
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decryptBytes = destMs.ToArray();
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}
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}
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}
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return decryptBytes;
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}
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}
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}
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