/* ====================================================================
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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.IO;
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using System.Text;
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using System.Xml;
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using HH.WMS.Utils.NPOI;
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using HH.WMS.Utils.NPOI.POIFS.FileSystem;
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namespace HH.WMS.Utils.NPOI.POIFS.Crypt
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{
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public class EncryptionHeader
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{
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public const int ALGORITHM_RC4 = 0x6801;
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public const int ALGORITHM_AES_128 = 0x660E;
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public const int ALGORITHM_AES_192 = 0x660F;
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public const int ALGORITHM_AES_256 = 0x6610;
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public const int HASH_SHA1 = 0x8004;
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public const int PROVIDER_RC4 = 1;
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public const int PROVIDER_AES = 0x18;
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public const int MODE_ECB = 1;
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public const int MODE_CBC = 2;
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public const int MODE_CFB = 3;
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private int flags;
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private int sizeExtra;
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private int algorithm;
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private int hashAlgorithm;
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private int keySize;
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private int providerType;
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private int cipherMode;
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private byte[] keySalt;
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private String cspName;
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public EncryptionHeader(DocumentInputStream dr)
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{
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flags = dr.ReadInt();
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sizeExtra = dr.ReadInt();
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algorithm = dr.ReadInt();
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hashAlgorithm = dr.ReadInt();
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keySize = dr.ReadInt();
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providerType = dr.ReadInt();
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dr.ReadLong(); //skip reserved.
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StringBuilder builder = new StringBuilder();
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while (true)
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{
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char c = (char)dr.ReadShort();
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if (c == 0)
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break;
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builder.Append(c);
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}
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cspName = builder.ToString();
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cipherMode = MODE_ECB;
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keySalt = null;
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}
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public EncryptionHeader(string descriptor)
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{
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try
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{
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XmlAttributeCollection keyData;
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try
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{
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MemoryStream ms = new MemoryStream(Encoding.Default.GetBytes(descriptor));
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XmlDocument xml = new XmlDocument();
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xml.Load(ms);
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XmlNodeList node = xml.GetElementsByTagName("keyData");
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keyData = node[0].Attributes;
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}
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catch (Exception)
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{
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throw new EncryptedDocumentException("Unable to parse keyData");
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}
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keySize = Int32.Parse(keyData.GetNamedItem("keyBits").Value);
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flags = 0;
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sizeExtra = 0;
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cspName = null;
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int blockSize = Int32.Parse(keyData.GetNamedItem("blockSize").Value);
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string cipher = keyData.GetNamedItem("cipherAlgorithm").Value;
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if ("AES".Equals(cipher))
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{
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providerType = PROVIDER_AES;
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if (blockSize == 16)
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algorithm = ALGORITHM_AES_128;
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else if (blockSize == 24)
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algorithm = ALGORITHM_AES_192;
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else if (blockSize == 32)
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algorithm = ALGORITHM_AES_256;
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else
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throw new EncryptedDocumentException("Unsupported key length");
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}
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else
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{
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throw new EncryptedDocumentException("Unsupported cipher");
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}
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string chaining = keyData.GetNamedItem("cipherChaining").Value;
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if ("ChainingModeCBC".Equals(chaining))
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cipherMode = MODE_CBC;
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else if ("ChainingModeCFB".Equals(chaining))
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cipherMode = MODE_CFB;
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else
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throw new EncryptedDocumentException("Unsupported chaining mode");
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string hasAlg = keyData.GetNamedItem("hashAlgorithm").Value;
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int hashSize = Int32.Parse(keyData.GetNamedItem("hashSize").Value);
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if("SHA1".Equals(hasAlg) && hashSize == 20)
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hashAlgorithm = HASH_SHA1;
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else
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throw new EncryptedDocumentException("Unsupported hash algorithm");
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string salt = keyData.GetNamedItem("saltValue").Value;
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int saltLength = Int32.Parse(keyData.GetNamedItem("saltSize").Value);
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//keySalt = Base64.DecodeBase64(Encoding.Default.GetBytes(salt));
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//keySalt = Base64.DecodeBase64(salt);
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keySalt = Convert.FromBase64String(salt);
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if(keySalt.Length != saltLength)
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throw new EncryptedDocumentException("Invalid salt length");
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}
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catch (IOException ex)
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{
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throw ex;
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}
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}
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public int CipherMode
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{
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get { return cipherMode; }
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}
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public int Flags
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{
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get { return flags; }
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}
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public int SizeExtra
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{
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get { return sizeExtra; }
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}
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public int Algorithm
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{
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get { return algorithm; }
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}
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public int HashAlgorithm
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{
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get { return hashAlgorithm; }
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}
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public int KeySize
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{
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get { return keySize; }
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}
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public byte[] KeySalt
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{
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get { return keySalt; }
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}
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public int ProviderType
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{
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get { return providerType; }
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}
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public string CspName
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{
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get { return cspName; }
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}
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}
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}
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