/* ==================================================================== 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. ==================================================================== */ using System; using System.Collections.Generic; using System.Text; using System.IO; using HH.WMS.Utils.NPOI.POIFS.FileSystem; using HH.WMS.Utils.NPOI.Util; using HH.WMS.Utils.NPOI; using System.Security; using System.Security.Cryptography; namespace HH.WMS.Utils.NPOI.POIFS.Crypt { public abstract class Decryptor { public static string DEFAULT_PASSWORD = "VelvetSweatshop"; public abstract Stream GetDataStream(DirectoryNode dir); public abstract bool VerifyPassword(string password); public static Decryptor GetInstance(EncryptionInfo info) { int major = info.VersionMajor; int minor = info.VersionMinor; if (major == 4 && minor == 4) return new AgileDecryptor(info); else if (minor == 2 && (major == 3 || major == 4)) return new EcmaDecryptor(info); else throw new EncryptedDocumentException("Unsupported version"); } public Stream GetDataStream(NPOIFSFileSystem fs) { return GetDataStream(fs.Root); } public Stream GetDataStream(POIFSFileSystem fs) { return GetDataStream(fs.Root); } protected static int GetBlockSize(int algorithm) { switch (algorithm) { case EncryptionHeader.ALGORITHM_AES_128: return 16; case EncryptionHeader.ALGORITHM_AES_192: return 24; case EncryptionHeader.ALGORITHM_AES_256: return 32; } throw new EncryptedDocumentException("Unknown block size"); } protected byte[] HashPassword(EncryptionInfo info, string password) { HashAlgorithm sha1 = HashAlgorithm.Create("SHA1"); byte[] bytes; try { bytes = Encoding.Unicode.GetBytes(password); //bytes = password.getBytes("UTF-16LE"); } catch (CryptographicUnexpectedOperationException) { throw new EncryptedDocumentException("UTF16 not supported"); } //sha1.ComputeHash(info.GetVerifier().Salt); byte[] salt = info.Verifier.Salt; byte[] temp = new byte[salt.Length + bytes.Length]; Array.Copy(salt, temp, salt.Length); Array.Copy(bytes, 0, temp, salt.Length, bytes.Length); byte[] hash = sha1.ComputeHash(temp); byte[] iterator = new byte[4]; temp = new byte[24]; for (int i = 0; i < info.Verifier.SpinCount; i++) { //sha1.Clear(); LittleEndian.PutInt(iterator, i); //sha1.iterator; //sha1.update(iterator); Array.Copy(iterator, temp, iterator.Length); Array.Copy(hash, 0, temp, iterator.Length, hash.Length); hash = sha1.ComputeHash(temp); } return hash; } protected byte[] Decrypt(SymmetricAlgorithm cipher,byte[] encryptBytes) { byte[] decryptBytes = new byte[0]; using (MemoryStream fStream = new MemoryStream(encryptBytes)) { using (CryptoStream cStream = new CryptoStream(fStream, cipher.CreateDecryptor(cipher.Key, cipher.IV), CryptoStreamMode.Read)) { using (MemoryStream destMs = new MemoryStream()) { byte[] buffer = new byte[100]; int readLen; while ((readLen = cStream.Read(buffer, 0, 100)) > 0) destMs.Write(buffer, 0, readLen); decryptBytes = destMs.ToArray(); } } } return decryptBytes; } } }