近期在使用“实时公交”软件,其有北京大部分公交车的GPS数据,但是软件比较偏国企化,做的并没有那么人性化,大山子路口这里剧堵是远近闻名的,基本上每辆车都要堵一段时间,那么冬天出去等车就会很遭罪,但是晚出去有可能眼睁睁的看着公交到站开走,所以打算逆向分析一下北京实时公交软件,加入对堵车时间的预测。
该软件如其外观一样简单,内部没有做混淆,甚至还有测试信息打印,System.out.println等输出,所以直接dex转jar(https://sourceforge.net/projects/dex2jar/),然后使用jd-gui(http://jd.benow.ca/)进行查看,导出来后放入IDE查看。
以下为其主要目录结构
model层应该是可以比较直观的看出其结构(其model层写了一个错别字?)
分析看到需要解密的字段,其使用RC4加解密,一个不是特别常用的对称加解密算法
RC4不是对明文进行分组处理,而是字节流的方式依次加密明文中的每一个字节,解密的时候也是依次对密文中的每一个字节进行解密。
算法简单,运行速度快,而且密钥长度是可变的,可变范围为1-256字节(8-2048比特)
1、密钥流:RC4算法的关键是根据明文和密钥生成相应的密钥流,密钥流的长度和明文的长度是对应的,也就是说明文的长度是500字节,那么密钥流也是500字节。当然,加密生成的密文也是500字节,因为密文第i字节=明文第i字节^密钥流第i字节;
2、状态向量S:长度为256,S[0],S[1]…..S[255]。每个单元都是一个字节,算法运行的任何时候,S都包括0-255的8比特数的排列组合,只不过值的位置发生了变换;
3、临时向量T:长度也为256,每个单元也是一个字节。如果密钥的长度是256字节,就直接把密钥的值赋给T,否则,轮转地将密钥的每个字节赋给T;
4、密钥K:长度为1-256字节,注意密钥的长度keylen与明文长度、密钥流的长度没有必然关系,通常密钥的长度趣味16字节(128比特)。
实现:
- function rc4($key, $pt)
- {
- $s = array();
- for ($i=0; $i<256; $i++) {
- $s[$i] = $i;
- }
- $j = 0;
- $key_len = strlen($key);
- for ($i=0; $i<256; $i++) {
- $j = ($j + $s[$i] + ord($key[$i % $key_len])) % 256;
- //swap
- $x = $s[$i];
- $s[$i] = $s[$j];
- $s[$j] = $x;
- }
- $i = 0;
- $j = 0;
- $ct = '';
- $data_len = strlen($pt);
- for ($y=0; $y< $data_len; $y++) {
- $i = ($i + 1) % 256;
- $j = ($j + $s[$i]) % 256;
- //swap
- $x = $s[$i];
- $s[$i] = $s[$j];
- $s[$j] = $x;
- $ct .= $pt[$y] ^ chr($s[($s[$i] + $s[$j]) % 256]);
- }
- return $ct;
- }
测试验证:
- $str = '{"root":{"status":"200","message":"success","encrypt":"1","num":"6","lid":"949","data":{"bus":[{"gt":"1511789342","id":"75544","t":"0","ns":"MeACxHFmZLhE","nsn":"5kU=","nsd":"1706","nsrt":"197","nst":"1511789539","sd":"+Uc=","srt":"+Uc=","st":"+Uc=","x":"5UewD9XUuDbzQw==","y":"4EaoEdPStDT4","lt":"0","ut":"1511789353"},{"gt":"1511789343","id":"75537","t":"0","ns":"9kh/iiYwnXfFvgPc4r4gjGxZ","nsn":"Ldk=","nsd":"652","nsrt":"79","nst":"1511789422","sd":"MtA=","srt":"MtA=","st":"MtA=","x":"LtDlQqCIRdFZaQ==","y":"K9H9XKaJRtVY","lt":"0","ut":"1511789354"},{"gt":"1511789334","id":"75611","t":"0","ns":"z60iAGP9avHwPh8dLCVw17Rv","nsn":"Gzw=","nsd":"-1","nsrt":"-1","nst":"-1","sd":"Bzg=","srt":"Bzg=","st":"Bzg=","x":"Gzizy+Z0tmpX4g==","y":"GTCr3Op6uW5S","lt":"0","ut":"1511789342"},{"gt":"1511789335","id":"75538","t":"0","ns":"q2CWQiHZ52ohG3yEEOiW","nsn":"fMs=","nsd":"321","nsrt":"52","nst":"1511789387","sd":"YM0=","srt":"YM0=","st":"YM0=","x":"fM07iK9COfuC","y":"fsUjn6JDNvg=","lt":"0","ut":"1511789343"},{"gt":"1511789256","id":"75549","t":"0","ns":"GlwsiqkbEEag","nsn":"wcI=","nsd":"515","nsrt":"71","nst":"1511789327","sd":"3sQ=","srt":"3sQ=","st":"3sQ=","x":"wsS2QRG8zfQcfA==","y":"x8WuXxa/y/kU","lt":"0","ut":"1511789270"},{"gt":"1511789107","id":"75553","t":"0","ns":"ZZQTCHtyjvXT3sBLOCJLdjq3","nsn":"sws=","nsd":"-1","nsrt":"-1","nst":"-1","sd":"rQg=","srt":"rQg=","st":"rQg=","x":"sQi8wPzyX0BIDw==","y":"tAmk3vr4X0NG","lt":"0","ut":"1511789130"}]}}}';
- $arr = json_decode($str,true);
- $arr = $arr['root']['data']['bus'];
- foreach ($arr as $key=>$val){
- echo date('Y-m-d H:i:s',$val['gt'])."\n";
- echo $val['id']."\n";
- echo $val['t']."\n";
- echo rc4(md5("aibang".$val['gt']), base64_decode($val['ns']))."\n";
- echo rc4(md5("aibang".$val['gt']), base64_decode($val['nsn']))."\n";
- echo $val['nsd']."\n";
- echo $val['nsrt']."\n";
- echo $val['nst']."\n";
- echo $val['sd']."\n";
- echo $val['srt']."\n";
- echo $val['nst']."\n";
- echo rc4(md5("aibang".$val['gt']), base64_decode($val['x']))."\n";
- echo rc4(md5("aibang".$val['gt']), base64_decode($val['y']))."\n";
- echo date('Y-m-d H:i:s',$val['ut'])."\n";
- echo date('Y-m-d H:i:s',$val['lt'])."\n";
- echo "******************************************************\n";
- }
实现:
- package testest;
- import java.security.MessageDigest;
- import java.security.NoSuchAlgorithmException;
- public class RC4
- {
- public static String decry_RC4(byte[] data, String key) {
- if (data == null || key == null) {
- return null;
- }
- return asString(RC4Base(data, key));
- }
- public static String decry_RC4(String data, String key) {
- if (data == null || key == null) {
- return null;
- }
- return new String(RC4Base(HexString2Bytes(data), key));
- }
- public static byte[] encry_RC4_byte(String data, String key) {
- if (data == null || key == null) {
- return null;
- }
- byte b_data[] = data.getBytes();
- return RC4Base(b_data, key);
- }
- public static String encry_RC4_string(String data, String key) {
- if (data == null || key == null) {
- return null;
- }
- return toHexString(asString(encry_RC4_byte(data, key)));
- }
- private static String asString(byte[] buf) {
- StringBuffer strbuf = new StringBuffer(buf.length);
- for (int i = 0; i < buf.length; i++) {
- strbuf.append((char) buf[i]);
- }
- return strbuf.toString();
- }
- private static byte[] initKey(String aKey) {
- byte[] b_key = aKey.getBytes();
- byte state[] = new byte[256];
- for (int i = 0; i < 256; i++) {
- state[i] = (byte) i;
- }
- int index1 = 0;
- int index2 = 0;
- if (b_key == null || b_key.length == 0) {
- return null;
- }
- for (int i = 0; i < 256; i++) {
- index2 = ((b_key[index1] & 0xff) + (state[i] & 0xff) + index2) & 0xff;
- byte tmp = state[i];
- state[i] = state[index2];
- state[index2] = tmp;
- index1 = (index1 + 1) % b_key.length;
- }
- return state;
- }
- private static String toHexString(String s) {
- String str = "";
- for (int i = 0; i < s.length(); i++) {
- int ch = (int) s.charAt(i);
- String s4 = Integer.toHexString(ch & 0xFF);
- if (s4.length() == 1) {
- s4 = '0' + s4;
- }
- str = str + s4;
- }
- return str;// 0x表示十六进制
- }
- private static byte[] HexString2Bytes(String src) {
- int size = src.length();
- byte[] ret = new byte[size / 2];
- byte[] tmp = src.getBytes();
- for (int i = 0; i < size / 2; i++) {
- ret[i] = uniteBytes(tmp[i * 2], tmp[i * 2 + 1]);
- }
- return ret;
- }
- private static byte uniteBytes(byte src0, byte src1) {
- char _b0 = (char)Byte.decode("0x" + new String(new byte[] { src0 }))
- .byteValue();
- _b0 = (char) (_b0 << 4);
- char _b1 = (char)Byte.decode("0x" + new String(new byte[] { src1 }))
- .byteValue();
- byte ret = (byte) (_b0 ^ _b1);
- return ret;
- }
- private static byte[] RC4Base (byte [] input, String mKkey) {
- int x = 0;
- int y = 0;
- byte key[] = initKey(mKkey);
- int xorIndex;
- byte[] result = new byte[input.length];
- for (int i = 0; i < input.length; i++) {
- x = (x + 1) & 0xff;
- y = ((key[x] & 0xff) + y) & 0xff;
- byte tmp = key[x];
- key[x] = key[y];
- key[y] = tmp;
- xorIndex = ((key[x] & 0xff) + (key[y] & 0xff)) & 0xff;
- result[i] = (byte) (input[i] ^ key[xorIndex]);
- }
- return result;
- }
- private static String encode(String paramString1, String paramString2)
- {
- try
- {
- MessageDigest localMessageDigest = MessageDigest.getInstance(paramString2);
- localMessageDigest.update(paramString1.getBytes());
- byte[] arrayOfByte = localMessageDigest.digest();
- StringBuilder localStringBuilder = new StringBuilder(2 * arrayOfByte.length);
- for (int i = 0; i < arrayOfByte.length; i++)
- {
- localStringBuilder.append(Integer.toHexString((0xF0 & arrayOfByte[i]) >>> 4));
- localStringBuilder.append(Integer.toHexString(0xF & arrayOfByte[i]));
- }
- String str = localStringBuilder.toString();
- return str;
- }
- catch (NoSuchAlgorithmException localNoSuchAlgorithmException)
- {
- localNoSuchAlgorithmException.printStackTrace();
- }
- return "";
- }
- }
验证
- public static void main(String[] args) throws NoSuchAlgorithmException {
- String md5 = encode("aibang1511793087","MD5");
- System.out.println(md5);
- byte[] b = Base64.decode("jT2f7w3uYkWWKvnwI4XpuD1X",0);
- System.out.println(new String(b));
- String test = null;
- test = new String(RC4.RC4Base(b, md5));
- System.out.println(test);
- }
附Base64实现
- package testest;
- import java.io.UnsupportedEncodingException;
- /**
- * Utilities for encoding and decoding the Base64 representation of
- * binary data. See RFCs <a
- * href="http://www.ietf.org/rfc/rfc2045.txt">2045</a> and <a
- * href="http://www.ietf.org/rfc/rfc3548.txt">3548</a>.
- */
- public class Base64 {
- /**
- * Default values for encoder/decoder flags.
- */
- public static final int DEFAULT = 0;
- /**
- * Encoder flag bit to omit the padding '=' characters at the end
- * of the output (if any).
- */
- public static final int NO_PADDING = 1;
- /**
- * Encoder flag bit to omit all line terminators (i.e., the output
- * will be on one long line).
- */
- public static final int NO_WRAP = 2;
- /**
- * Encoder flag bit to indicate lines should be terminated with a
- * CRLF pair instead of just an LF. Has no effect if {@code
- * NO_WRAP} is specified as well.
- */
- public static final int CRLF = 4;
- /**
- * Encoder/decoder flag bit to indicate using the "URL and
- * filename safe" variant of Base64 (see RFC 3548 section 4) where
- * {@code -} and {@code _} are used in place of {@code +} and
- * {@code /}.
- */
- public static final int URL_SAFE = 8;
- /**
- * Flag to pass to {@link Base64OutputStream} to indicate that it
- * should not close the output stream it is wrapping when it
- * itself is closed.
- */
- public static final int NO_CLOSE = 16;
- // --------------------------------------------------------
- // shared code
- // --------------------------------------------------------
- /* package */ static abstract class Coder {
- public byte[] output;
- public int op;
- /**
- * Encode/decode another block of input data. this.output is
- * provided by the caller, and must be big enough to hold all
- * the coded data. On exit, this.opwill be set to the length
- * of the coded data.
- *
- * @param finish true if this is the final call to process for
- * this object. Will finalize the coder state and
- * include any final bytes in the output.
- *
- * @return true if the input so far is good; false if some
- * error has been detected in the input stream..
- */
- public abstract boolean process(byte[] input, int offset, int len, boolean finish);
- /**
- * @return the maximum number of bytes a call to process()
- * could produce for the given number of input bytes. This may
- * be an overestimate.
- */
- public abstract int maxOutputSize(int len);
- }
- // --------------------------------------------------------
- // decoding
- // --------------------------------------------------------
- /**
- * Decode the Base64-encoded data in input and return the data in
- * a new byte array.
- *
- * <p>The padding '=' characters at the end are considered optional, but
- * if any are present, there must be the correct number of them.
- *
- * @param str the input String to decode, which is converted to
- * bytes using the default charset
- * @param flags controls certain features of the decoded output.
- * Pass {@code DEFAULT} to decode standard Base64.
- *
- * @throws IllegalArgumentException if the input contains
- * incorrect padding
- */
- public static byte[] decode(String str, int flags) {
- return decode(str.getBytes(), flags);
- }
- /**
- * Decode the Base64-encoded data in input and return the data in
- * a new byte array.
- *
- * <p>The padding '=' characters at the end are considered optional, but
- * if any are present, there must be the correct number of them.
- *
- * @param input the input array to decode
- * @param flags controls certain features of the decoded output.
- * Pass {@code DEFAULT} to decode standard Base64.
- *
- * @throws IllegalArgumentException if the input contains
- * incorrect padding
- */
- public static byte[] decode(byte[] input, int flags) {
- return decode(input, 0, input.length, flags);
- }
- /**
- * Decode the Base64-encoded data in input and return the data in
- * a new byte array.
- *
- * <p>The padding '=' characters at the end are considered optional, but
- * if any are present, there must be the correct number of them.
- *
- * @param input the data to decode
- * @param offset the position within the input array at which to start
- * @param len the number of bytes of input to decode
- * @param flags controls certain features of the decoded output.
- * Pass {@code DEFAULT} to decode standard Base64.
- *
- * @throws IllegalArgumentException if the input contains
- * incorrect padding
- */
- public static byte[] decode(byte[] input, int offset, int len, int flags) {
- // Allocate space for the most data the input could represent.
- // (It could contain less if it contains whitespace, etc.)
- Decoder decoder = new Decoder(flags, new byte[len*3/4]);
- if (!decoder.process(input, offset, len, true)) {
- throw new IllegalArgumentException("bad base-64");
- }
- // Maybe we got lucky and allocated exactly enough output space.
- if (decoder.op == decoder.output.length) {
- return decoder.output;
- }
- // Need to shorten the array, so allocate a new one of the
- // right size and copy.
- byte[] temp = new byte[decoder.op];
- System.arraycopy(decoder.output, 0, temp, 0, decoder.op);
- return temp;
- }
- /* package */ static class Decoder extends Coder {
- /**
- * Lookup table for turning bytes into their position in the
- * Base64 alphabet.
- */
- private static final int DECODE[] = {
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,
- 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -2, -1, -1,
- -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
- 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
- -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
- 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1,
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
- };
- /**
- * Decode lookup table for the "web safe" variant (RFC 3548
- * sec. 4) where - and _ replace + and /.
- */
- private static final int DECODE_WEBSAFE[] = {
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1,
- 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -2, -1, -1,
- -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
- 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, 63,
- -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
- 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1,
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
- -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
- };
- /** Non-data values in the DECODE arrays. */
- private static final int SKIP = -1;
- private static final int EQUALS = -2;
- /**
- * States 0-3 are reading through the next input tuple.
- * State 4 is having read one '=' and expecting exactly
- * one more.
- * State 5 is expecting no more data or padding characters
- * in the input.
- * State 6 is the error state; an error has been detected
- * in the input and no future input can "fix" it.
- */
- private int state; // state number (0 to 6)
- private int value;
- final private int[] alphabet;
- public Decoder(int flags, byte[] output) {
- this.output = output;
- alphabet = ((flags & URL_SAFE) == 0) ? DECODE : DECODE_WEBSAFE;
- state = 0;
- value = 0;
- }
- /**
- * @return an overestimate for the number of bytes {@code
- * len} bytes could decode to.
- */
- public int maxOutputSize(int len) {
- return len * 3/4 + 10;
- }
- /**
- * Decode another block of input data.
- *
- * @return true if the state machine is still healthy. false if
- * bad base-64 data has been detected in the input stream.
- */
- public boolean process(byte[] input, int offset, int len, boolean finish) {
- if (this.state == 6) return false;
- int p = offset;
- len += offset;
- // Using local variables makes the decoder about 12%
- // faster than if we manipulate the member variables in
- // the loop. (Even alphabet makes a measurable
- // difference, which is somewhat surprising to me since
- // the member variable is final.)
- int state = this.state;
- int value = this.value;
- int op = 0;
- final byte[] output = this.output;
- final int[] alphabet = this.alphabet;
- while (p < len) {
- // Try the fast path: we're starting a new tuple and the
- // next four bytes of the input stream are all data
- // bytes. This corresponds to going through states
- // 0-1-2-3-0. We expect to use this method for most of
- // the data.
- //
- // If any of the next four bytes of input are non-data
- // (whitespace, etc.), value will end up negative. (All
- // the non-data values in decode are small negative
- // numbers, so shifting any of them up and or'ing them
- // together will result in a value with its top bit set.)
- //
- // You can remove this whole block and the output should
- // be the same, just slower.
- if (state == 0) {
- while (p+4 <= len &&
- (value = ((alphabet[input[p] & 0xff] << 18) |
- (alphabet[input[p+1] & 0xff] << 12) |
- (alphabet[input[p+2] & 0xff] << 6) |
- (alphabet[input[p+3] & 0xff]))) >= 0) {
- output[op+2] = (byte) value;
- output[op+1] = (byte) (value >> 8);
- output[op] = (byte) (value >> 16);
- op += 3;
- p += 4;
- }
- if (p >= len) break;
- }
- // The fast path isn't available -- either we've read a
- // partial tuple, or the next four input bytes aren't all
- // data, or whatever. Fall back to the slower state
- // machine implementation.
- int d = alphabet[input[p++] & 0xff];
- switch (state) {
- case 0:
- if (d >= 0) {
- value = d;
- ++state;
- } else if (d != SKIP) {
- this.state = 6;
- return false;
- }
- break;
- case 1:
- if (d >= 0) {
- value = (value << 6) | d;
- ++state;
- } else if (d != SKIP) {
- this.state = 6;
- return false;
- }
- break;
- case 2:
- if (d >= 0) {
- value = (value << 6) | d;
- ++state;
- } else if (d == EQUALS) {
- // Emit the last (partial) output tuple;
- // expect exactly one more padding character.
- output[op++] = (byte) (value >> 4);
- state = 4;
- } else if (d != SKIP) {
- this.state = 6;
- return false;
- }
- break;
- case 3:
- if (d >= 0) {
- // Emit the output triple and return to state 0.
- value = (value << 6) | d;
- output[op+2] = (byte) value;
- output[op+1] = (byte) (value >> 8);
- output[op] = (byte) (value >> 16);
- op += 3;
- state = 0;
- } else if (d == EQUALS) {
- // Emit the last (partial) output tuple;
- // expect no further data or padding characters.
- output[op+1] = (byte) (value >> 2);
- output[op] = (byte) (value >> 10);
- op += 2;
- state = 5;
- } else if (d != SKIP) {
- this.state = 6;
- return false;
- }
- break;
- case 4:
- if (d == EQUALS) {
- ++state;
- } else if (d != SKIP) {
- this.state = 6;
- return false;
- }
- break;
- case 5:
- if (d != SKIP) {
- this.state = 6;
- return false;
- }
- break;
- }
- }
- if (!finish) {
- // We're out of input, but a future call could provide
- // more.
- this.state = state;
- this.value = value;
- this.op = op;
- return true;
- }
- // Done reading input. Now figure out where we are left in
- // the state machine and finish up.
- switch (state) {
- case 0:
- // Output length is a multiple of three. Fine.
- break;
- case 1:
- // Read one extra input byte, which isn't enough to
- // make another output byte. Illegal.
- this.state = 6;
- return false;
- case 2:
- // Read two extra input bytes, enough to emit 1 more
- // output byte. Fine.
- output[op++] = (byte) (value >> 4);
- break;
- case 3:
- // Read three extra input bytes, enough to emit 2 more
- // output bytes. Fine.
- output[op++] = (byte) (value >> 10);
- output[op++] = (byte) (value >> 2);
- break;
- case 4:
- // Read one padding '=' when we expected 2. Illegal.
- this.state = 6;
- return false;
- case 5:
- // Read all the padding '='s we expected and no more.
- // Fine.
- break;
- }
- this.state = state;
- this.op = op;
- return true;
- }
- }
- // --------------------------------------------------------
- // encoding
- // --------------------------------------------------------
- /**
- * Base64-encode the given data and return a newly allocated
- * String with the result.
- *
- * @param input the data to encode
- * @param flags controls certain features of the encoded output.
- * Passing {@code DEFAULT} results in output that
- * adheres to RFC 2045.
- */
- public static String encodeToString(byte[] input, int flags) {
- try {
- return new String(encode(input, flags), "US-ASCII");
- } catch (UnsupportedEncodingException e) {
- // US-ASCII is guaranteed to be available.
- throw new AssertionError(e);
- }
- }
- /**
- * Base64-encode the given data and return a newly allocated
- * String with the result.
- *
- * @param input the data to encode
- * @param offset the position within the input array at which to
- * start
- * @param len the number of bytes of input to encode
- * @param flags controls certain features of the encoded output.
- * Passing {@code DEFAULT} results in output that
- * adheres to RFC 2045.
- */
- public static String encodeToString(byte[] input, int offset, int len, int flags) {
- try {
- return new String(encode(input, offset, len, flags), "US-ASCII");
- } catch (UnsupportedEncodingException e) {
- // US-ASCII is guaranteed to be available.
- throw new AssertionError(e);
- }
- }
- /**
- * Base64-encode the given data and return a newly allocated
- * byte[] with the result.
- *
- * @param input the data to encode
- * @param flags controls certain features of the encoded output.
- * Passing {@code DEFAULT} results in output that
- * adheres to RFC 2045.
- */
- public static byte[] encode(byte[] input, int flags) {
- return encode(input, 0, input.length, flags);
- }
- /**
- * Base64-encode the given data and return a newly allocated
- * byte[] with the result.
- *
- * @param input the data to encode
- * @param offset the position within the input array at which to
- * start
- * @param len the number of bytes of input to encode
- * @param flags controls certain features of the encoded output.
- * Passing {@code DEFAULT} results in output that
- * adheres to RFC 2045.
- */
- public static byte[] encode(byte[] input, int offset, int len, int flags) {
- Encoder encoder = new Encoder(flags, null);
- // Compute the exact length of the array we will produce.
- int output_len = len / 3 * 4;
- // Account for the tail of the data and the padding bytes, if any.
- if (encoder.do_padding) {
- if (len % 3 > 0) {
- output_len += 4;
- }
- } else {
- switch (len % 3) {
- case 0: break;
- case 1: output_len += 2; break;
- case 2: output_len += 3; break;
- }
- }
- // Account for the newlines, if any.
- if (encoder.do_newline && len > 0) {
- output_len += (((len-1) / (3 * Encoder.LINE_GROUPS)) + 1) *
- (encoder.do_cr ? 2 : 1);
- }
- encoder.output = new byte[output_len];
- encoder.process(input, offset, len, true);
- assert encoder.op == output_len;
- return encoder.output;
- }
- /* package */ static class Encoder extends Coder {
- /**
- * Emit a new line every this many output tuples. Corresponds to
- * a 76-character line length (the maximum allowable according to
- * <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>).
- */
- public static final int LINE_GROUPS = 19;
- /**
- * Lookup table for turning Base64 alphabet positions (6 bits)
- * into output bytes.
- */
- private static final byte ENCODE[] = {
- 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
- 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
- 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
- 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/',
- };
- /**
- * Lookup table for turning Base64 alphabet positions (6 bits)
- * into output bytes.
- */
- private static final byte ENCODE_WEBSAFE[] = {
- 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
- 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
- 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
- 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-', '_',
- };
- final private byte[] tail;
- /* package */ int tailLen;
- private int count;
- final public boolean do_padding;
- final public boolean do_newline;
- final public boolean do_cr;
- final private byte[] alphabet;
- public Encoder(int flags, byte[] output) {
- this.output = output;
- do_padding = (flags & NO_PADDING) == 0;
- do_newline = (flags & NO_WRAP) == 0;
- do_cr = (flags & CRLF) != 0;
- alphabet = ((flags & URL_SAFE) == 0) ? ENCODE : ENCODE_WEBSAFE;
- tail = new byte[2];
- tailLen = 0;
- count = do_newline ? LINE_GROUPS : -1;
- }
- /**
- * @return an overestimate for the number of bytes {@code
- * len} bytes could encode to.
- */
- public int maxOutputSize(int len) {
- return len * 8/5 + 10;
- }
- public boolean process(byte[] input, int offset, int len, boolean finish) {
- // Using local variables makes the encoder about 9% faster.
- final byte[] alphabet = this.alphabet;
- final byte[] output = this.output;
- int op = 0;
- int count = this.count;
- int p = offset;
- len += offset;
- int v = -1;
- // First we need to concatenate the tail of the previous call
- // with any input bytes available now and see if we can empty
- // the tail.
- switch (tailLen) {
- case 0:
- // There was no tail.
- break;
- case 1:
- if (p+2 <= len) {
- // A 1-byte tail with at least 2 bytes of
- // input available now.
- v = ((tail[0] & 0xff) << 16) |
- ((input[p++] & 0xff) << 8) |
- (input[p++] & 0xff);
- tailLen = 0;
- };
- break;
- case 2:
- if (p+1 <= len) {
- // A 2-byte tail with at least 1 byte of input.
- v = ((tail[0] & 0xff) << 16) |
- ((tail[1] & 0xff) << 8) |
- (input[p++] & 0xff);
- tailLen = 0;
- }
- break;
- }
- if (v != -1) {
- output[op++] = alphabet[(v >> 18) & 0x3f];
- output[op++] = alphabet[(v >> 12) & 0x3f];
- output[op++] = alphabet[(v >> 6) & 0x3f];
- output[op++] = alphabet[v & 0x3f];
- if (--count == 0) {
- if (do_cr) output[op++] = '\r';
- output[op++] = '\n';
- count = LINE_GROUPS;
- }
- }
- // At this point either there is no tail, or there are fewer
- // than 3 bytes of input available.
- // The main loop, turning 3 input bytes into 4 output bytes on
- // each iteration.
- while (p+3 <= len) {
- v = ((input[p] & 0xff) << 16) |
- ((input[p+1] & 0xff) << 8) |
- (input[p+2] & 0xff);
- output[op] = alphabet[(v >> 18) & 0x3f];
- output[op+1] = alphabet[(v >> 12) & 0x3f];
- output[op+2] = alphabet[(v >> 6) & 0x3f];
- output[op+3] = alphabet[v & 0x3f];
- p += 3;
- op += 4;
- if (--count == 0) {
- if (do_cr) output[op++] = '\r';
- output[op++] = '\n';
- count = LINE_GROUPS;
- }
- }
- if (finish) {
- // Finish up the tail of the input. Note that we need to
- // consume any bytes in tail before any bytes
- // remaining in input; there should be at most two bytes
- // total.
- if (p-tailLen == len-1) {
- int t = 0;
- v = ((tailLen > 0 ? tail[t++] : input[p++]) & 0xff) << 4;
- tailLen -= t;
- output[op++] = alphabet[(v >> 6) & 0x3f];
- output[op++] = alphabet[v & 0x3f];
- if (do_padding) {
- output[op++] = '=';
- output[op++] = '=';
- }
- if (do_newline) {
- if (do_cr) output[op++] = '\r';
- output[op++] = '\n';
- }
- } else if (p-tailLen == len-2) {
- int t = 0;
- v = (((tailLen > 1 ? tail[t++] : input[p++]) & 0xff) << 10) |
- (((tailLen > 0 ? tail[t++] : input[p++]) & 0xff) << 2);
- tailLen -= t;
- output[op++] = alphabet[(v >> 12) & 0x3f];
- output[op++] = alphabet[(v >> 6) & 0x3f];
- output[op++] = alphabet[v & 0x3f];
- if (do_padding) {
- output[op++] = '=';
- }
- if (do_newline) {
- if (do_cr) output[op++] = '\r';
- output[op++] = '\n';
- }
- } else if (do_newline && op > 0 && count != LINE_GROUPS) {
- if (do_cr) output[op++] = '\r';
- output[op++] = '\n';
- }
- assert tailLen == 0;
- assert p == len;
- } else {
- // Save the leftovers in tail to be consumed on the next
- // call to encodeInternal.
- if (p == len-1) {
- tail[tailLen++] = input[p];
- } else if (p == len-2) {
- tail[tailLen++] = input[p];
- tail[tailLen++] = input[p+1];
- }
- }
- this.op = op;
- this.count = count;
- return true;
- }
- }
- private Base64() { } // don't instantiate
- }
最终可以看到其站名公交车GPS速度等内容
- ******************************************************
- 2017-11-27 21:28:54
- 75611
- 0
- 大山子路口南
- 15
- -1
- -1
- -1
- -1
- -1
- -1
- 116.489674
- 39.986622
- 2017-11-27 21:29:02
- 0
- ******************************************************
来源: https://juejin.im/entry/5a1fce1b6fb9a045263b5e66