将解密文件读入ZipInputStream有时会截断第一个文件
我正在开发一个电子阅读器应用程序（使用skyepub ），它基本上将加密的书籍下载到文件系统中（它保存的是数据库中的解密密钥），当用户试图读取它时，它将书籍加载到内存中，解密它。
问题是有些书的第一章被截断（epub书籍实际上是zip文件，每章都是一个单独的文件）..这导致了这个可怕的错误：
此XML文件似乎没有与之关联的任何样式信息。 文档树如下所示
我试过的
我已经validation加密的书籍是否正确下载，如果我将文件复制到我的桌面（来自我的root用户机器人），并且在其上运行此命令，则b / c：
openssl aes-192-cbc -d -K *** -iv *** -in test.epub.encrypted -out test.epub 它工作得很好。 但是，如果我几乎尝试使用以下android代码执行相同操作
public ContentData getContentData(String baseDirectory, String contentPath) { if( contentPath.startsWith("/fonts/")) { ... // handle font suff } int secondSlash = contentPath.indexOf('/', 1); if( secondSlash == -1) return null; String bookEditionID = contentPath.substring(1,secondSlash); String zipEntryName = contentPath.substring(secondSlash+1); final ContentData data = new ContentData(); try { InputStream stream = dbUtil.getBookStream(bookEditionID); if( stream == null) return null; final ZipInputStream zip = new ZipInputStream(stream); ZipEntry entry; do { entry = zip.getNextEntry(); Log.e("Abjjad","looping through entry: "+entry); if( entry == null) { zip.close(); return null; } } while( !entry.getName().equals(zipEntryName)); Log.e("debug","going through data with entry: " +entry+", contentLength: "+entry.getSize());
请参阅方法dbUtil.getBookStream ：
public InputStream getBookStream( String bookEditionId) { BookInfo book = getBookInfo(bookEditionId); InputStream origStream = null; try { // Open the downloaded ePub origStream = openFileInput(bookEditionId + ".epub"); // De-obfuscate the key SecretKeySpec sks = getObfuscationKeySpec(bookEditionId); Cipher c = Cipher.getInstance("AES/ECB/PKCS5Padding", "BC"); c.init(Cipher.DECRYPT_MODE, sks); byte[] decodedBytes = c.doFinal(Base64.decode(book.decryptionKey, Base64.DEFAULT)); String keyPair = new String(decodedBytes); // Split the key and parse into binary int separator = keyPair.indexOf(':'); byte[] key = DatatypeConverter.parseHexBinary(keyPair.substring(0, separator)); byte[] iv = DatatypeConverter.parseHexBinary(keyPair.substring(separator + 1)); c = Cipher.getInstance("AES/CBC/PKCS7Padding","BC"); c.init(Cipher.DECRYPT_MODE, new SecretKeySpec(key,"AES"), new IvParameterSpec(iv)); return new CipherInputStream(origStream, c); } catch( Exception e) { try { if (origStream != null) origStream.close(); } catch( Exception x) {} return null; } }
然后，entry.getSize（）的日志在第一个代码块中返回-1 。
奖金（适用于iOS！）
我们在iOS中编写了相同的代码，它完美地工作（在同一本书上）：
+ (NSData *)encryptKey:(NSString *)key ivParam:(NSString *)iv bookId:(NSString *)bookId { NSString *keyPair = [NSString stringWithFormat:@"%@:%@", key, iv]; NSString *secret = [self getObfuscationSecretWithValue:bookId]; NSData *data = [keyPair dataUsingEncoding:NSASCIIStringEncoding]; char keyPtr[kCCKeySizeAES128]; bzero(keyPtr, sizeof(keyPtr)); [[NSData dataWithHexString:secret] getBytes:keyPtr length:sizeof(keyPtr)]; NSUInteger dataLength = [data length]; size_t bufferSize = dataLength + kCCBlockSizeAES128; void *buffer = malloc(bufferSize); size_t numBytesEncrypted; CCCryptorStatus status = CCCrypt(kCCEncrypt, kCCAlgorithmAES, kCCOptionPKCS7Padding | kCCOptionECBMode, keyPtr, kCCKeySizeAES128, NULL, [data bytes], [data length], buffer, bufferSize, &numBytesEncrypted); if (status == kCCSuccess) { return [NSData dataWithBytes:buffer length:numBytesEncrypted]; } else { free(buffer); return nil; } }
更新
我注意到这个截断只是在阅读了toc之后（这似乎是上面的最后一章？）..来自日志：
::::::::::::::::::::::::::::::: getInputStream: /24748681/OEBPS/toc.ncx ::::::::::::::::::::::::::::::: looping through entry: mimetype looping through entry: OEBPS/hayat-ghayr.html looping through entry: OEBPS/content.opf looping through entry: OEBPS/images/978-614-425-313-7-hayat-ghayr-cover.png looping through entry: OEBPS/images/978-614-425-313-7-hayat_fmt.png looping through entry: OEBPS/template.css looping through entry: OEBPS/hayat-ghayr-2.html looping through entry: OEBPS/hayat-ghayr-1.html looping through entry: OEBPS/hayat-ghayr-3.html looping through entry: OEBPS/hayat-ghayr-4.html looping through entry: OEBPS/hayat-ghayr-5.html looping through entry: OEBPS/hayat-ghayr-6.html looping through entry: OEBPS/hayat-ghayr-7.html looping through entry: OEBPS/hayat-ghayr-8.html looping through entry: OEBPS/hayat-ghayr-9.html looping through entry: OEBPS/hayat-ghayr-10.html looping through entry: OEBPS/hayat-ghayr-11.html looping through entry: OEBPS/hayat-ghayr-12.html looping through entry: OEBPS/hayat-ghayr-13.html looping through entry: OEBPS/hayat-ghayr-14.html looping through entry: OEBPS/hayat-ghayr-15.html looping through entry: OEBPS/hayat-ghayr-16.html looping through entry: OEBPS/hayat-ghayr-17.html looping through entry: OEBPS/hayat-ghayr-18.html looping through entry: OEBPS/hayat-ghayr-19.html looping through entry: OEBPS/hayat-ghayr-20.html looping through entry: OEBPS/hayat-ghayr-21.html looping through entry: OEBPS/hayat-ghayr-22.html looping through entry: META-INF/container.xml looping through entry: OEBPS/images/277.png looping through entry: OEBPS/toc.ncx going through data with entry: OEBPS/toc.ncx, contentLength: 5549 returning data ::::::::::::::::::::::::::::::: getInputStream: /24748681/OEBPS/hayat-ghayr.html ::::::::::::::::::::::::::::::: looping through entry: mimetype looping through entry: OEBPS/hayat-ghayr.html going through data with entry: OEBPS/hayat-ghayr.html, contentLength: -1 returning data
根据文档 ，如果大小未知，getSize（）可能返回-1。 这肯定发生在一些zip文件中。 在这些情况下，您需要读取整个条目以确定其未压缩的大小。
分析
红鲱鱼
首先，整个加密解密的事情是一个红色的鲱鱼..简单地复制相同的 epub / zip文件并使用相同的代码读取它导致相同的页面..所以这是zip文件本身而不是解密的问题它
Zip文档
正如java doc中提到的，如果内容未知（这正是这里发生的事情），读取zip文件实际上可以返回-1 ..事实上，我们得到了相同的 zip文件，解压缩它（在命令上） line）然后用增加的压缩级别重新压缩它，如下所示：
zip -9 -r filename.epub *
然后我们将相同的zip文件提供给现有代码，它完美地工作！
解
所以这是最终的代码：
try { InputStream stream = abjjadDb.getBookStream(bookEditionID); if( stream == null) return null; final ZipInputStream zip = new ZipInputStream(stream); ZipEntry entry; do { entry = zip.getNextEntry(); if( entry == null) { zip.close(); return null; } } while( !entry.getName().equals(zipEntryName)); data.contentLength = entry.getSize(); data.lastModified = entry.getTime(); data.contentPath = contentPath; InputStream s = zip; if( data.contentLength == -1) { Log.e("demo",new Object(){}.getClass().getEnclosingMethod().getName()+":: entry \""+entry+"\" has contentLength -1, so we will work around"); ByteArrayOutputStream buffer = new ByteArrayOutputStream(); int nRead; // use buf to store data from the zip file entry in fixed size byte[] buf = new byte[4096]; while ((nRead = zip.read(buf)) != -1) { // dump that data into buffer, which is a growing buffer buffer.write(buf, 0, nRead); } buffer.flush(); byte[] finalBuffer = buffer.toByteArray(); Log.e("demo",new Object(){}.getClass().getEnclosingMethod().getName()+":: entry \""+entry+"\" final data length: "+finalBuffer.length); data.contentLength = finalBuffer.length; s = new ByteArrayInputStream(finalBuffer); } final InputStream finalStream = s;
并且日志给了我们这个
getContentData:: entry "OEBPS/hayat-ghayr.html" has contentLength -1, so we will work around getContentData:: entry "OEBPS/hayat-ghayr.html" final data length: 2378 getContentData:: entry "OEBPS/hayat-ghayr.html" has contentLength -1, so we will work around getContentData:: entry "OEBPS/hayat-ghayr.html" final data length: 2378
有趣的是..如果我们在命令行上运行它，那个大小与该文件hayat-ghayr的实际内容长度完全匹配：
$ unzip -l b17c024e-89f1-42f7-a546-91d46610cedb.epub Archive: b17c024e-89f1-42f7-a546-91d46610cedb.epub Length Date Time Name -------- ---- ---- ---- 20 01-27-12 11:17 mimetype 2378 04-20-12 10:12 OEBPS/hayat-ghayr.html 6436 02-06-12 11:06 OEBPS/content.opf 112579 01-27-12 11:25 OEBPS/images/978-614-425-313-7-hayat-ghayr-cover.png 182575 01-27-12 11:25 OEBPS/images/978-614-425-313-7-hayat_fmt.png 7757 01-27-12 11:21 OEBPS/template.css 5643 01-27-12 11:18 OEBPS/hayat-ghayr-2.html 20144 01-27-12 11:17 OEBPS/hayat-ghayr-1.html 65543 01-27-12 11:17 OEBPS/hayat-ghayr-3.html 59434 01-27-12 11:17 OEBPS/hayat-ghayr-4.html 66768 01-27-12 11:17 OEBPS/hayat-ghayr-5.html 49117 01-27-12 11:17 OEBPS/hayat-ghayr-6.html 65346 01-27-12 11:17 OEBPS/hayat-ghayr-7.html 74196 01-27-12 11:17 OEBPS/hayat-ghayr-8.html 73998 01-27-12 11:17 OEBPS/hayat-ghayr-9.html 61031 01-27-12 11:17 OEBPS/hayat-ghayr-10.html 68297 01-27-12 11:17 OEBPS/hayat-ghayr-11.html 72084 01-27-12 11:17 OEBPS/hayat-ghayr-12.html 2386 01-27-12 11:17 OEBPS/hayat-ghayr-13.html 61132 01-27-12 11:17 OEBPS/hayat-ghayr-14.html 46320 01-27-12 11:17 OEBPS/hayat-ghayr-15.html 32673 01-27-12 11:17 OEBPS/hayat-ghayr-16.html 88584 01-27-12 11:17 OEBPS/hayat-ghayr-17.html 56474 01-27-12 11:17 OEBPS/hayat-ghayr-18.html 52840 01-27-12 11:17 OEBPS/hayat-ghayr-19.html 80022 01-27-12 11:17 OEBPS/hayat-ghayr-20.html 50781 01-27-12 11:17 OEBPS/hayat-ghayr-21.html 2765 01-27-12 11:17 OEBPS/hayat-ghayr-22.html 265 01-27-12 11:17 META-INF/container.xml 54942 01-27-12 11:17 OEBPS/images/277.png 5549 01-27-12 11:17 OEBPS/toc.ncx 1072 03-23-12 13:28 iTunesMetadata.plist -------- ------- 1529151 32 files