MD5信息摘要算法（英語：MD5 Message-Digest Algorithm），一種被廣泛使用的密碼散列函數(shù)，可以產(chǎn)生出一個(gè)128位（16字節(jié)）的散列值（hash value），用于確保信息傳輸完整一致。MD5由美國密碼學(xué)家羅納德·李維斯特（Ronald Linn Rivest）設(shè)計(jì)，于1992年公開，用以取代MD4算法。這套算法的程序在 RFC 1321 標(biāo)準(zhǔn)中被加以規(guī)范。1996年后該算法被證實(shí)存在弱點(diǎn)，可以被加以破解，對(duì)于需要高度安全性的數(shù)據(jù)，專家一般建議改用其他算法，如SHA-2。2004年，證實(shí)MD5算法無法防止碰撞（collision），因此不適用于安全性認(rèn)證，如SSL公開密鑰認(rèn)證或是數(shù)字簽名等用途。

/************************************************ MD5 算法的Java Bean Last Modified:10,Mar,2001*************************************************/ import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; import java.math.BigInteger; import java.security.MessageDigest; import java.util.HashMap; import java.util.Map; import java.util.zip.CRC32; import java.util.zip.CheckedInputStream;/************************************************** md5 類實(shí)現(xiàn)了RSA Data Security, Inc.在提交給IETF 的RFC1321中的MD5 message-digest 算法。*************************************************/ public class MD5 {/** 下面這些S11-S44實(shí)際上是一個(gè)44的矩陣，在原始的C實(shí)現(xiàn)中是用#define 實(shí)現(xiàn)的， 這里把它們實(shí)現(xiàn)成為static* final是表示了只讀，切能在同一個(gè)進(jìn)程空間內(nèi)的多個(gè) Instance間共享*/private static final int S11 = 7;private static final int S12 = 12;private static final int S13 = 17;private static final int S14 = 22;private static final int S21 = 5;private static final int S22 = 9;private static final int S23 = 14;private static final int S24 = 20;private static final int S31 = 4;private static final int S32 = 11;private static final int S33 = 16;private static final int S34 = 23;private static final int S41 = 6;private static final int S42 = 10;private static final int S43 = 15;private static final int S44 = 21;private static final byte[] PADDING = { -128, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,0, 0, 0, 0 };/** 下面的三個(gè)成員是MD5計(jì)算過程中用到的3個(gè)核心數(shù)據(jù)，在原始的C實(shí)現(xiàn)中 被定義到MD5_CTX結(jié)構(gòu)中*/private long[] state = new long[4]; // state (ABCD)private long[] count = new long[2]; // number of bits, modulo 2^64 (lsb// first)private byte[] buffer = new byte[64]; // input buffer/** digestHexStr是MD5的唯一一個(gè)公共成員，是最新一次計(jì)算結(jié)果的 16進(jìn)制ASCII表示.*/private String digestHexStr;/** digest,是最新一次計(jì)算結(jié)果的2進(jìn)制內(nèi)部表示，表示128bit的MD5值.*/private byte[] digest = new byte[16];/*** getMD5ofStr是類MD5最主要的公共方法，入口參數(shù)是你想要進(jìn)行MD5變換的字符串* 返回的是變換完的結(jié)果，這個(gè)結(jié)果是從公共成員digestHexStr取得的．*/public String getMD5ofStr(String inbuf) {md5Init();md5Update(inbuf.getBytes(), inbuf.length());md5Final();digestHexStr = "";for (int i = 0; i < 16; i++) {digestHexStr += byteHEX(digest[i]);}return digestHexStr;}// 這是MD5這個(gè)類的標(biāo)準(zhǔn)構(gòu)造函數(shù)，JavaBean要求有一個(gè)public的并且沒有參數(shù)的構(gòu)造函數(shù)public MD5() {md5Init();return;}/* md5Init是一個(gè)初始化函數(shù)，初始化核心變量，裝入標(biāo)準(zhǔn)的幻數(shù) */private void md5Init() {count[0] = 0L;count[1] = 0L;// /* Load magic initialization constants.state[0] = 0x67452301L;state[1] = 0xefcdab89L;state[2] = 0x98badcfeL;state[3] = 0x10325476L;return;}/** F, G, H ,I 是4個(gè)基本的MD5函數(shù)，在原始的MD5的C實(shí)現(xiàn)中，由于它們是* 簡單的位運(yùn)算，可能出于效率的考慮把它們實(shí)現(xiàn)成了宏，在java中，我們把它們 實(shí)現(xiàn)成了private方法，名字保持了原來C中的。*/private long F(long x, long y, long z) {return (x & y) | ((~x) & z);}private long G(long x, long y, long z) {return (x & z) | (y & (~z));}private long H(long x, long y, long z) {return x ^ y ^ z;}private long I(long x, long y, long z) {return y ^ (x | (~z));}/** Rotation is separate from addition to prevent recomputation.*/private long FF(long a, long b, long c, long d, long x, long s, long ac) {a += F(b, c, d) + x + ac;a = ((int) a << s) | ((int) a >>> (32 - s));a += b;return a;}private long GG(long a, long b, long c, long d, long x, long s, long ac) {a += G(b, c, d) + x + ac;a = ((int) a << s) | ((int) a >>> (32 - s));a += b;return a;}private long HH(long a, long b, long c, long d, long x, long s, long ac) {a += H(b, c, d) + x + ac;a = ((int) a << s) | ((int) a >>> (32 - s));a += b;return a;}private long II(long a, long b, long c, long d, long x, long s, long ac) {a += I(b, c, d) + x + ac;a = ((int) a << s) | ((int) a >>> (32 - s));a += b;return a;}/** md5Update是MD5的主計(jì)算過程，inbuf是要變換的字節(jié)串，inputlen是長度，這個(gè)* 函數(shù)由getMD5ofStr調(diào)用，調(diào)用之前需要調(diào)用md5init，因此把它設(shè)計(jì)成private的*/private void md5Update(byte[] inbuf, int inputLen) {int i, index, partLen;byte[] block = new byte[64];index = (int) (count[0] >>> 3) & 0x3F;// /* Update number of bits */if ((count[0] += (inputLen << 3)) < (inputLen << 3))count[1]++;count[1] += (inputLen >>> 29);partLen = 64 - index;// Transform as many times as possible.if (inputLen >= partLen) {md5Memcpy(buffer, inbuf, index, 0, partLen);md5Transform(buffer);for (i = partLen; i + 63 < inputLen; i += 64) {md5Memcpy(block, inbuf, 0, i, 64);md5Transform(block);}index = 0;} elsei = 0;// /* Buffer remaining input */md5Memcpy(buffer, inbuf, index, i, inputLen - i);}/** md5Final整理和填寫輸出結(jié)果*/private void md5Final() {byte[] bits = new byte[8];int index, padLen;// /* Save number of bits */Encode(bits, count, 8);// /* Pad out to 56 mod 64.index = (int) (count[0] >>> 3) & 0x3f;padLen = (index < 56) ? (56 - index) : (120 - index);md5Update(PADDING, padLen);// /* Append length (before padding) */md5Update(bits, 8);// /* Store state in digest */Encode(digest, state, 16);}/** md5Memcpy是一個(gè)內(nèi)部使用的byte數(shù)組的塊拷貝函數(shù)，從input的inpos開始把len長度的* 字節(jié)拷貝到output的outpos位置開始*/private void md5Memcpy(byte[] output, byte[] input, int outpos, int inpos, int len) {int i;for (i = 0; i < len; i++)output[outpos + i] = input[inpos + i];}/** md5Transform是MD5核心變換程序，有md5Update調(diào)用，block是分塊的原始字節(jié)*/private void md5Transform(byte block[]) {long a = state[0], b = state[1], c = state[2], d = state[3];long[] x = new long[16];Decode(x, block, 64);/* Round 1 */a = FF(a, b, c, d, x[0], S11, 0xd76aa478L); /* 1 */d = FF(d, a, b, c, x[1], S12, 0xe8c7b756L); /* 2 */c = FF(c, d, a, b, x[2], S13, 0x242070dbL); /* 3 */b = FF(b, c, d, a, x[3], S14, 0xc1bdceeeL); /* 4 */a = FF(a, b, c, d, x[4], S11, 0xf57c0fafL); /* 5 */d = FF(d, a, b, c, x[5], S12, 0x4787c62aL); /* 6 */c = FF(c, d, a, b, x[6], S13, 0xa8304613L); /* 7 */b = FF(b, c, d, a, x[7], S14, 0xfd469501L); /* 8 */a = FF(a, b, c, d, x[8], S11, 0x698098d8L); /* 9 */d = FF(d, a, b, c, x[9], S12, 0x8b44f7afL); /* 10 */c = FF(c, d, a, b, x[10], S13, 0xffff5bb1L); /* 11 */b = FF(b, c, d, a, x[11], S14, 0x895cd7beL); /* 12 */a = FF(a, b, c, d, x[12], S11, 0x6b901122L); /* 13 */d = FF(d, a, b, c, x[13], S12, 0xfd987193L); /* 14 */c = FF(c, d, a, b, x[14], S13, 0xa679438eL); /* 15 */b = FF(b, c, d, a, x[15], S14, 0x49b40821L); /* 16 *//* Round 2 */a = GG(a, b, c, d, x[1], S21, 0xf61e2562L); /* 17 */d = GG(d, a, b, c, x[6], S22, 0xc040b340L); /* 18 */c = GG(c, d, a, b, x[11], S23, 0x265e5a51L); /* 19 */b = GG(b, c, d, a, x[0], S24, 0xe9b6c7aaL); /* 20 */a = GG(a, b, c, d, x[5], S21, 0xd62f105dL); /* 21 */d = GG(d, a, b, c, x[10], S22, 0x2441453L); /* 22 */c = GG(c, d, a, b, x[15], S23, 0xd8a1e681L); /* 23 */b = GG(b, c, d, a, x[4], S24, 0xe7d3fbc8L); /* 24 */a = GG(a, b, c, d, x[9], S21, 0x21e1cde6L); /* 25 */d = GG(d, a, b, c, x[14], S22, 0xc33707d6L); /* 26 */c = GG(c, d, a, b, x[3], S23, 0xf4d50d87L); /* 27 */b = GG(b, c, d, a, x[8], S24, 0x455a14edL); /* 28 */a = GG(a, b, c, d, x[13], S21, 0xa9e3e905L); /* 29 */d = GG(d, a, b, c, x[2], S22, 0xfcefa3f8L); /* 30 */c = GG(c, d, a, b, x[7], S23, 0x676f02d9L); /* 31 */b = GG(b, c, d, a, x[12], S24, 0x8d2a4c8aL); /* 32 *//* Round 3 */a = HH(a, b, c, d, x[5], S31, 0xfffa3942L); /* 33 */d = HH(d, a, b, c, x[8], S32, 0x8771f681L); /* 34 */c = HH(c, d, a, b, x[11], S33, 0x6d9d6122L); /* 35 */b = HH(b, c, d, a, x[14], S34, 0xfde5380cL); /* 36 */a = HH(a, b, c, d, x[1], S31, 0xa4beea44L); /* 37 */d = HH(d, a, b, c, x[4], S32, 0x4bdecfa9L); /* 38 */c = HH(c, d, a, b, x[7], S33, 0xf6bb4b60L); /* 39 */b = HH(b, c, d, a, x[10], S34, 0xbebfbc70L); /* 40 */a = HH(a, b, c, d, x[13], S31, 0x289b7ec6L); /* 41 */d = HH(d, a, b, c, x[0], S32, 0xeaa127faL); /* 42 */c = HH(c, d, a, b, x[3], S33, 0xd4ef3085L); /* 43 */b = HH(b, c, d, a, x[6], S34, 0x4881d05L); /* 44 */a = HH(a, b, c, d, x[9], S31, 0xd9d4d039L); /* 45 */d = HH(d, a, b, c, x[12], S32, 0xe6db99e5L); /* 46 */c = HH(c, d, a, b, x[15], S33, 0x1fa27cf8L); /* 47 */b = HH(b, c, d, a, x[2], S34, 0xc4ac5665L); /* 48 *//* Round 4 */a = II(a, b, c, d, x[0], S41, 0xf4292244L); /* 49 */d = II(d, a, b, c, x[7], S42, 0x432aff97L); /* 50 */c = II(c, d, a, b, x[14], S43, 0xab9423a7L); /* 51 */b = II(b, c, d, a, x[5], S44, 0xfc93a039L); /* 52 */a = II(a, b, c, d, x[12], S41, 0x655b59c3L); /* 53 */d = II(d, a, b, c, x[3], S42, 0x8f0ccc92L); /* 54 */c = II(c, d, a, b, x[10], S43, 0xffeff47dL); /* 55 */b = II(b, c, d, a, x[1], S44, 0x85845dd1L); /* 56 */a = II(a, b, c, d, x[8], S41, 0x6fa87e4fL); /* 57 */d = II(d, a, b, c, x[15], S42, 0xfe2ce6e0L); /* 58 */c = II(c, d, a, b, x[6], S43, 0xa3014314L); /* 59 */b = II(b, c, d, a, x[13], S44, 0x4e0811a1L); /* 60 */a = II(a, b, c, d, x[4], S41, 0xf7537e82L); /* 61 */d = II(d, a, b, c, x[11], S42, 0xbd3af235L); /* 62 */c = II(c, d, a, b, x[2], S43, 0x2ad7d2bbL); /* 63 */b = II(b, c, d, a, x[9], S44, 0xeb86d391L); /* 64 */state[0] += a;state[1] += b;state[2] += c;state[3] += d;}/** Encode把long數(shù)組按順序拆成byte數(shù)組，因?yàn)閖ava的long類型是64bit的， 只拆低32bit，以適應(yīng)原始C實(shí)現(xiàn)的用途*/private void Encode(byte[] output, long[] input, int len) {int i, j;for (i = 0, j = 0; j < len; i++, j += 4) {output[j] = (byte) (input[i] & 0xffL);output[j + 1] = (byte) ((input[i] >>> 8) & 0xffL);output[j + 2] = (byte) ((input[i] >>> 16) & 0xffL);output[j + 3] = (byte) ((input[i] >>> 24) & 0xffL);}}/** Decode把byte數(shù)組按順序合成成long數(shù)組，因?yàn)閖ava的long類型是64bit的，* 只合成低32bit，高32bit清零，以適應(yīng)原始C實(shí)現(xiàn)的用途*/private void Decode(long[] output, byte[] input, int len) {int i, j;for (i = 0, j = 0; j < len; i++, j += 4)output[i] = b2iu(input[j]) | (b2iu(input[j + 1]) << 8) | (b2iu(input[j + 2]) << 16)| (b2iu(input[j + 3]) << 24);return;}/*** b2iu是我寫的一個(gè)把byte按照不考慮正負(fù)號(hào)的原則的＂升位＂程序，因?yàn)閖ava沒有unsigned運(yùn)算*/public static long b2iu(byte b) {return b < 0 ? b & 0x7F + 128 : b;}/*** byteHEX()，用來把一個(gè)byte類型的數(shù)轉(zhuǎn)換成十六進(jìn)制的ASCII表示，* 因?yàn)閖ava中的byte的toString無法實(shí)現(xiàn)這一點(diǎn)，我們又沒有C語言中的 sprintf(outbuf,"%02X",ib)*/public static String byteHEX(byte ib) {char[] Digit = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };char[] ob = new char[2];ob[0] = Digit[(ib >>> 4) & 0X0F];ob[1] = Digit[ib & 0X0F];String s = new String(ob);return s;}// -----------------------------------------------------------/*** 獲取單個(gè)文件的MD5值！* * @param file* @return*/public static String getFileMD5(File file) {if (!file.isFile()) {return null;}MessageDigest digest = null;FileInputStream in = null;byte buffer[] = new byte[1024];int len;try {digest = MessageDigest.getInstance("MD5");in = new FileInputStream(file);while ((len = in.read(buffer, 0, 1024)) != -1) {digest.update(buffer, 0, len);}in.close();} catch (Exception e) {e.printStackTrace();return null;}BigInteger bigInt = new BigInteger(1, digest.digest());return bigInt.toString(16).toUpperCase();}/*** 獲取單個(gè)文件的SHA1值！* * @param file* @return*/public static String getFileSHA1(File file) {if (!file.isFile()) {return null;}MessageDigest digest = null;FileInputStream in = null;byte buffer[] = new byte[1024];int len;try {digest = MessageDigest.getInstance("SHA1");in = new FileInputStream(file);while ((len = in.read(buffer, 0, 1024)) != -1) {digest.update(buffer, 0, len);}in.close();} catch (Exception e) {e.printStackTrace();return null;}BigInteger bigInt = new BigInteger(1, digest.digest());return bigInt.toString(16).toUpperCase();}/*** 獲取單個(gè)文件的CRC32值！* * @param file* @return* @throws Exception*/public static String getFileCRC32(File file) {FileInputStream fileinputstream;try {fileinputstream = new FileInputStream(file);CRC32 crc32 = new CRC32();for (CheckedInputStream checkedinputstream = new CheckedInputStream(fileinputstream,crc32); checkedinputstream.read() != -1;) {}return Long.toHexString(crc32.getValue());} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}return null;}/*** 獲取文件夾中文件的MD5值* * @param file* @param listChild* ;true遞歸子目錄中的文件* @return*/public static Map<String, String> getDirMD5(File file, boolean listChild) {if (!file.isDirectory()) {return null;}// <filepath,md5>Map<String, String> map = new HashMap<>();String md5;File files[] = file.listFiles();for (int i = 0; i < files.length; i++) {File f = files[i];if (f.isDirectory() && listChild) {map.putAll(getDirMD5(f, listChild));} else {md5 = getFileMD5(f);if (md5 != null) {map.put(f.getPath(), md5);}}}return map;}/*** 獲取文件夾中文件的SHA1值* * @param file* @param listChild* ;true遞歸子目錄中的文件* @return*/public static Map<String, String> getDirSHA1(File file, boolean listChild) {if (!file.isDirectory()) {return null;}// <filepath,SHA1>Map<String, String> map = new HashMap<>();String sha1;File files[] = file.listFiles();for (int i = 0; i < files.length; i++) {File f = files[i];if (f.isDirectory() && listChild) {map.putAll(getDirSHA1(f, listChild));} else {sha1 = getFileSHA1(f);if (sha1 != null) {map.put(f.getPath(), sha1);}}}return map;}/*** 獲取文件夾中文件的CRC32值* * @param file* @param listChild* ;true遞歸子目錄中的文件* @return*/public static Map<String, String> getDirCRC32(File file, boolean listChild) {if (!file.isDirectory()) {return null;}// <filepath,CRC32>Map<String, String> map = new HashMap<>();String crc32;File files[] = file.listFiles();for (int i = 0; i < files.length; i++) {File f = files[i];if (f.isDirectory() && listChild) {map.putAll(getDirCRC32(f, listChild));} else {crc32 = getFileCRC32(f);if (crc32 != null) {map.put(f.getPath(), crc32);}}}return map;} }

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