Android下的加密信息客户端 WhisperSystems-TextSecure.zip

package org.thoughtcrime.securesms.util; import java.io.IOException; /** * <p>Encodes and decodes to and from Base64 notation.</p> * <p>Homepage: <a href="http://iharder.net/base64">http://iharder.net/base64</a>.</p> * * <p>Example:</p> * * <code>String encoded = Base64.encode( myByteArray );</code> * <br /> * <code>byte[] myByteArray = Base64.decode( encoded );</code> * * <p>The <tt>options</tt> parameter, which appears in a few places, is used to pass * several pieces of information to the encoder. In the "higher level" methods such as * encodeBytes( bytes, options ) the options parameter can be used to indicate such * things as first gzipping the bytes before encoding them, not inserting linefeeds, * and encoding using the URL-safe and Ordered dialects.</p> * * <p>Note, according to <a href="http://www.faqs.org/rfcs/rfc3548.html">RFC3548</a>, * Section 2.1, implementations should not add line feeds unless explicitly told * to do so. I've got Base64 set to this behavior now, although earlier versions * broke lines by default.</p> * * <p>The constants defined in Base64 can be OR-ed together to combine options, so you * might make a call like this:</p> * * <code>String encoded = Base64.encodeBytes( mybytes, Base64.GZIP | Base64.DO_BREAK_LINES );</code> * <p>to compress the data before encoding it and then making the output have newline characters.</p> * <p>Also...</p> * <code>String encoded = Base64.encodeBytes( crazyString.getBytes() );</code> * * * * <p> * Change Log: * </p> * <ul> * <li>v2.3.4 - Fixed bug when working with gzipped streams whereby flushing * the Base64.OutputStream closed the Base64 encoding (by padding with equals * signs) too soon. Also added an option to suppress the automatic decoding * of gzipped streams. Also added experimental support for specifying a * class loader when using the * {@link #decodeToObject(java.lang.String, int, java.lang.ClassLoader)} * method.</li> * <li>v2.3.3 - Changed default char encoding to US-ASCII which reduces the internal Java * footprint with its CharEncoders and so forth. Fixed some javadocs that were * inconsistent. Removed imports and specified things like java.io.IOException * explicitly inline.</li> * <li>v2.3.2 - Reduced memory footprint! Finally refined the "guessing" of how big the * final encoded data will be so that the code doesn't have to create two output * arrays: an oversized initial one and then a final, exact-sized one. Big win * when using the {@link #encodeBytesToBytes(byte[])} family of methods (and not * using the gzip options which uses a different mechanism with streams and stuff).</li> * <li>v2.3.1 - Added {@link #encodeBytesToBytes(byte[], int, int, int)} and some * similar helper methods to be more efficient with memory by not returning a * String but just a byte array.</li> * <li>v2.3 - <strong>This is not a drop-in replacement!</strong> This is two years of comments * and bug fixes queued up and finally executed. Thanks to everyone who sent * me stuff, and I'm sorry I wasn't able to distribute your fixes to everyone else. * Much bad coding was cleaned up including throwing exceptions where necessary * instead of returning null values or something similar. Here are some changes * that may affect you: * <ul> * <li><em>Does not break lines, by default.</em> This is to keep in compliance with * <a href="http://www.faqs.org/rfcs/rfc3548.html">RFC3548</a>.</li> * <li><em>Throws exceptions instead of returning null values.</em> Because some operations * (especially those that may permit the GZIP option) use IO streams, there * is a possiblity of an java.io.IOException being thrown. After some discussion and * thought, I've changed the behavior of the methods to throw java.io.IOExceptions * rather than return null if ever there's an error. I think this is more * appropriate, though it will require some changes to your code. Sorry, * it should have been done this way to begin with.</li> * <li><em>Removed all references to System.out, System.err, and the like.</em> * Shame on me. All I can say is sorry they were ever there.</li> * <li><em>Throws NullPointerExceptions and IllegalArgumentExceptions</em> as needed * such as when passed arrays are null or offsets are invalid.</li> * <li>Cleaned up as much javadoc as I could to avoid any javadoc warnings. * This was especially annoying before for people who were thorough in their * own projects and then had gobs of javadoc warnings on this file.</li> * </ul> * <li>v2.2.1 - Fixed bug using URL_SAFE and ORDERED encodings. Fixed bug * when using very small files (~< 40 bytes).</li> * <li>v2.2 - Added some helper methods for encoding/decoding directly from * one file to the next. Also added a main() method to support command line * encoding/decoding from one file to the next. Also added these Base64 dialects: * <ol> * <li>The default is RFC3548 format.</li> * <li>Calling Base64.setFormat(Base64.BASE64_FORMAT.URLSAFE_FORMAT) generates * URL and file name friendly format as described in Section 4 of RFC3548. * http://www.faqs.org/rfcs/rfc3548.html</li> * <li>Calling Base64.setFormat(Base64.BASE64_FORMAT.ORDERED_FORMAT) generates * URL and file name friendly format that preserves lexical ordering as described * in http://www.faqs.org/qa/rfcc-1940.html</li> * </ol> * Special thanks to Jim Kellerman at <a href="http://www.powerset.com/">http://www.powerset.com/</a> * for contributing the new Base64 dialects. * </li> * * <li>v2.1 - Cleaned up javadoc comments and unused variables and methods. Added * some convenience methods for reading and writing to and from files.</li> * <li>v2.0.2 - Now specifies UTF-8 encoding in places where the code fails on systems * with other encodings (like EBCDIC).</li> * <li>v2.0.1 - Fixed an error when decoding a single byte, that is, when the * encoded data was a single byte.</li> * <li>v2.0 - I got rid of methods that used booleans to set options. * Now everything is more consolidated and cleaner. The code now detects * when data that's being decoded is gzip-compressed and will decompress it * automatically. Generally things are cleaner. You'll probably have to * change some method calls that you were making to support the new * options format (<tt>int</tt>s that you "OR" together).</li> * <li>v1.5.1 - Fixed bug when decompressing and decoding to a * byte[] using <tt>decode( String s, boolean gzipCompressed )</tt>. * Added the ability to "suspend" encoding in the Output Stream so * you can turn on and off the encoding if you need to embed base64 * data in an otherwise "normal" stream (like an XML file).</li> * <li>v1.5 - Output stream pases on flush() command but doesn't do anything itself. * This helps when using GZIP streams. * Added the ability to GZip-compress objects before encoding them.</li> * <li>v1.4 - Added helper methods to read/write files.</li> * <li>v1.3.6 - Fixed OutputStream.flush() so that 'position' is reset.</li> * <li>v1.3.5 - Added flag to turn on and off line breaks. Fixed bug in input stream * where last buffer being read, if not completely full, was not returned.</li> * <li>v1.3.4 - Fixed when "improperly padded stream" error was thrown at the wrong time.</li> * <li>v1.3.3 - Fixed I/O streams which were totally messed up.</li> * </ul> * * <p> * I am placing this code in the Public Domain. Do with it as you will. * This software comes with no guarantees or warranties but with * plenty of well-wishing instead! * Please visit <a href="http://iharder.net/base64">http://iharder.net/base64</a> * periodically to check for updates or to contribute improvements. * </p> * * @author Robert Harder * @author rob@iharder.net *