浅谈加密算法BCrypt
@Test
public void contextLoads() {
String password = "12345";
String hashed = BCrypt.hashpw(password, BCrypt.gensalt());
System.out.println(hashed);
String hashed01 = BCrypt.hashpw(password, BCrypt.gensalt());
System.out.println(hashed01);
String hashed02 = BCrypt.hashpw(password, BCrypt.gensalt());
System.out.println(hashed02);
String hashed03 = BCrypt.hashpw(password, BCrypt.gensalt());
System.out.println(hashed03);
String hashed04 = BCrypt.hashpw(password, BCrypt.gensalt());
System.out.println(hashed04);
String hashed05 = BCrypt.hashpw(password, BCrypt.gensalt());
System.out.println(hashed05);
// gensalt's log_rounds parameter determines the complexity
// the work factor is 2**log_rounds, and the default is 10
String hashed2 = BCrypt.hashpw(password, BCrypt.gensalt(12));
// Check that an unencrypted password matches one that has
// previously been hashed
String candidate = "12345";
if (BCrypt.checkpw(candidate, hashed))
System.out.println("It matches");
else
System.out.println("It does not match");
}
在最新的Springboot secrity包中，登录加密的方式是BCrypt
当然，也可以直接下载BCrypt的jar包，进行加密和判断输入是否一致
<dependency>
<groupId>org.mindrot</groupId>
<artifactId>jbcrypt</artifactId>
<version>0.4</version>
</dependency>
也可以到官网 http://www.mindrot.org/projects/jBCrypt/
ok，依赖的事情说完时候，可以用上述测试代码查看一下，加密之后的字符串，运行了对于字符串12345的加密，结果如下
其中：$是分割符，无意义；2a是bcrypt加密版本号；10是cost的值；而后的前22位是salt值；再然后的字符串就是密码的密文了。
这块代码的格式拼接可以查看gensalt()方法源码：
从最下面往上看，返回log_rounds = 10，这就是版本号；
下一步，返回版本号和引用对象；
下一步，rs指向一个StringBuffer对象，先不管三七二十一，添加 $2a$
再判断 log_rounds 的值，小于10的按照0处理，大于30的抛出异常
11-29之间（包含），在 $2a$ 先添加 log_rounds 的值，再添加 $ , 再添加 base64位的加密
这一切之后，返回了salt值
public static String hashpw(String password, String salt) {
char minor = 0;
int off = false;
StringBuffer rs = new StringBuffer();
if (salt.charAt(0) == '$' && salt.charAt(1) == '2') {
byte off;
if (salt.charAt(2) == '$') {
off = 3;
} else {
minor = salt.charAt(2);
if (minor != 'a' || salt.charAt(3) != '$') {
throw new IllegalArgumentException("Invalid salt revision");
}
off = 4;
}
if (salt.charAt(off + 2) > '$') {
throw new IllegalArgumentException("Missing salt rounds");
} else {
int rounds = Integer.parseInt(salt.substring(off, off + 2));
String real_salt = salt.substring(off + 3, off + 25);
byte[] passwordb;
try {
passwordb = (password + (minor >= 'a' ? "\u0000" : "")).getBytes("UTF-8");
} catch (UnsupportedEncodingException var12) {
throw new AssertionError("UTF-8 is not supported");
}
byte[] saltb = decode_base64(real_salt, 16);
BCrypt B = new BCrypt();
byte[] hashed = B.crypt_raw(passwordb, saltb, rounds, (int[])((int[])bf_crypt_ciphertext.clone()));
rs.append("$2");
if (minor >= 'a') {
rs.append(minor);
}
rs.append("$");
if (rounds < 10) {
rs.append("0");
}
if (rounds > 30) {
throw new IllegalArgumentException("rounds exceeds maximum (30)");
} else {
rs.append(Integer.toString(rounds));
rs.append("$");
rs.append(encode_base64(saltb, saltb.length));
rs.append(encode_base64(hashed, bf_crypt_ciphertext.length * 4 - 1));
return rs.toString();
}
}
} else {
throw new IllegalArgumentException("Invalid salt version");
}
}
之后加密计算返回加密后的字符串，方法名是hashpw，具体实现有点长，复制了代码如上
具体的encode_base64加密和解密，和我以前了解的不太一致
以前的了解是单个字符串进行base64加密和解密，可逆 https://www.cnblogs.com/qianjinyan/p/9541368.html
而此时是如下
//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//
package org.mindrot.jbcrypt;
import java.io.UnsupportedEncodingException;
import java.security.SecureRandom;
public class BCrypt {
private static final int GENSALT_DEFAULT_LOG2_ROUNDS = 10;
private static final int BCRYPT_SALT_LEN = 16;
private static final int BLOWFISH_NUM_ROUNDS = 16;
private static final int[] P_orig = new int[]{608135816, -2052912941, 320440878, 57701188, -1542899678, 698298832, 137296536, -330404727, 1160258022, 953160567, -1101764913, 887688300, -1062458953, -914599715, 1065670069, -1253635817, -1843997223, -1988494565};
private static final int[] S_orig = new int[]{-785314906, -1730169428, 805139163, -803545161, -1193168915, 1780907670, -1166241723, -248741991, 614570311, -1282315017, 134345442, -2054226922, 1667834072, 1901547113, -1537671517, -191677058, 227898511, 1921955416, 1904987480, -2112533778, 2069144605, -1034266187, -1674521287, 720527379, -976113629, 677414384, -901678824, -1193592593, -1904616272, 1614419982, 1822297739, -1340175810, -686458943, -1120842969, 2024746970, 1432378464, -430627341, -1437226092, 1464375394, 1676153920, 1439316330, 715854006, -1261675468, 289532110, -1588296017, 2087905683, -1276242927, 1668267050, 732546397, 1947742710, -832815594, -1685613794, -1344882125, 1814351708, 2050118529, 680887927, 999245976, 1800124847, -994056165, 1713906067, 1641548236, -81679983, 1216130144, 1575780402, -276538019, -377129551, -601480446, -345695352, 596196993, -745100091, 258830323, -2081144263, 772490370, -1534844924, 1774776394, -1642095778, 566650946, -152474470, 1728879713, 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-877994476, -288586052, 1617046695, -1666491221, -1292663698, 1686838959, 431878346, -1608291911, 1700445008, 1080580658, 1009431731, 832498133, -1071531785, -1688990951, -2023776103, -1778935426, 1648197032, -130578278, -1746719369, 300782431, 375919233, 238389289, -941219882, -1763778655, 2019080857, 1475708069, 455242339, -1685863425, 448939670, -843904277, 1395535956, -1881585436, 1841049896, 1491858159, 885456874, -30872223, -293847949, 1565136089, -396052509, 1108368660, 540939232, 1173283510, -1549095958, -613658859, -87339056, -951913406, -278217803, 1699691293, 1103962373, -669091426, -2038084153, -464828566, 1031889488, -815619598, 1535977030, -58162272, -1043876189, 2132092099, 1774941330, 1199868427, 1452454533, 157007616, -1390851939, 342012276, 595725824, 1480756522, 206960106, 497939518, 591360097, 863170706, -1919713727, -698356495, 1814182875, 2094937945, -873565088, 1082520231, -831049106, -1509457788, 435703966, -386934699, 1641649973, -1452693590, -989067582, 1510255612, -2146710820, -1639679442, -1018874748, -36346107, 236887753, -613164077, 274041037, 1734335097, -479771840, -976997275, 1899903192, 1026095262, -244449504, 356393447, -1884275382, -421290197, -612127241, -381855128, -1803468553, -162781668, -1805047500, 1091903735, 1979897079, -1124832466, -727580568, -737663887, 857797738, 1136121015, 1342202287, 507115054, -1759230650, 337727348, -1081374656, 1301675037, -1766485585, 1895095763, 1721773893, -1078195732, 62756741, 2142006736, 835421444, -1762973773, 1442658625, -635090970, -1412822374, 676362277, 1392781812, 170690266, -373920261, 1759253602, -683120384, 1745797284, 664899054, 1329594018, -393761396, -1249058810, 2062866102, -1429332356, -751345684, -830954599, 1080764994, 553557557, -638351943, -298199125, 991055499, 499776247, 1265440854, 648242737, -354183246, 980351604, -581221582, 1749149687, -898096901, -83167922, -654396521, 1161844396, -1169648345, 1431517754, 545492359, -26498633, -795437749, 1437099964, 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1172426758, -1007518822, -911584259, 1655181056, -1155153950, 901632758, 1897031941, -1308360158, -1228157060, -847864789, 1393639104, 373351379, 950779232, 625454576, -1170726756, -146354570, 2007998917, 544563296, -2050228658, -1964470824, 2058025392, 1291430526, 424198748, 50039436, 29584100, -689184263, -1865090967, -1503863136, 1057563949, -1039604065, -1219600078, -831004069, 1469046755, 985887462};
private static final int[] bf_crypt_ciphertext = new int[]{1332899944, 1700884034, 1701343084, 1684370003, 1668446532, 1869963892};
private static final char[] base64_code = new char[]{'.', '/', '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'};
private static final byte[] index_64 = new byte[]{-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, -1, -1, -1, -1, -1, -1, -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, 26, 27, -1, -1, -1, -1, -1, -1, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, -1, -1, -1, -1, -1};
private int[] P;
private int[] S;
public BCrypt() {
}
private static String encode_base64(byte[] d, int len) throws IllegalArgumentException {
int off = 0;
StringBuffer rs = new StringBuffer();
if (len > 0 && len <= d.length) {
while(off < len) {
int c1 = d[off++] & 255;
rs.append(base64_code[c1 >> 2 & 63]);
c1 = (c1 & 3) << 4;
if (off >= len) {
rs.append(base64_code[c1 & 63]);
break;
}
int c2 = d[off++] & 255;
c1 |= c2 >> 4 & 15;
rs.append(base64_code[c1 & 63]);
c1 = (c2 & 15) << 2;
if (off >= len) {
rs.append(base64_code[c1 & 63]);
break;
}
c2 = d[off++] & 255;
c1 |= c2 >> 6 & 3;
rs.append(base64_code[c1 & 63]);
rs.append(base64_code[c2 & 63]);
}
return rs.toString();
} else {
throw new IllegalArgumentException("Invalid len");
}
}
private static byte char64(char x) {
return x >= 0 && x <= index_64.length ? index_64[x] : -1;
}
private static byte[] decode_base64(String s, int maxolen) throws IllegalArgumentException {
StringBuffer rs = new StringBuffer();
int off = 0;
int slen = s.length();
int olen = 0;
if (maxolen <= 0) {
throw new IllegalArgumentException("Invalid maxolen");
} else {
while(off < slen - 1 && olen < maxolen) {
byte c1 = char64(s.charAt(off++));
byte c2 = char64(s.charAt(off++));
if (c1 == -1 || c2 == -1) {
break;
}
byte o = (byte)(c1 << 2);
o = (byte)(o | (c2 & 48) >> 4);
rs.append((char)o);
++olen;
if (olen >= maxolen || off >= slen) {
break;
}
byte c3 = char64(s.charAt(off++));
if (c3 == -1) {
break;
}
o = (byte)((c2 & 15) << 4);
o = (byte)(o | (c3 & 60) >> 2);
rs.append((char)o);
++olen;
if (olen >= maxolen || off >= slen) {
break;
}
byte c4 = char64(s.charAt(off++));
o = (byte)((c3 & 3) << 6);
o |= c4;
rs.append((char)o);
++olen;
}
byte[] ret = new byte[olen];
for(off = 0; off < olen; ++off) {
ret[off] = (byte)rs.charAt(off);
}
return ret;
}
}
private final void encipher(int[] lr, int off) {
int l = lr[off];
int r = lr[off + 1];
l ^= this.P[0];
int n;
for(int i = 0; i <= 14; l ^= n ^ this.P[i]) {
n = this.S[l >> 24 & 255];
n += this.S[256 | l >> 16 & 255];
n ^= this.S[512 | l >> 8 & 255];
n += this.S[768 | l & 255];
++i;
r ^= n ^ this.P[i];
n = this.S[r >> 24 & 255];
n += this.S[256 | r >> 16 & 255];
n ^= this.S[512 | r >> 8 & 255];
n += this.S[768 | r & 255];
++i;
}
lr[off] = r ^ this.P[17];
lr[off + 1] = l;
}
private static int streamtoword(byte[] data, int[] offp) {
int word = 0;
int off = offp[0];
for(int i = 0; i < 4; ++i) {
word = word << 8 | data[off] & 255;
off = (off + 1) % data.length;
}
offp[0] = off;
return word;
}
private void init_key() {
this.P = (int[])((int[])P_orig.clone());
this.S = (int[])((int[])S_orig.clone());
}
private void key(byte[] key) {
int[] koffp = new int[]{0};
int[] lr = new int[]{0, 0};
int plen = this.P.length;
int slen = this.S.length;
int i;
for(i = 0; i < plen; ++i) {
this.P[i] ^= streamtoword(key, koffp);
}
for(i = 0; i < plen; i += 2) {
this.encipher(lr, 0);
this.P[i] = lr[0];
this.P[i + 1] = lr[1];
}
for(i = 0; i < slen; i += 2) {
this.encipher(lr, 0);
this.S[i] = lr[0];
this.S[i + 1] = lr[1];
}
}
private void ekskey(byte[] data, byte[] key) {
int[] koffp = new int[]{0};
int[] doffp = new int[]{0};
int[] lr = new int[]{0, 0};
int plen = this.P.length;
int slen = this.S.length;
int i;
for(i = 0; i < plen; ++i) {
this.P[i] ^= streamtoword(key, koffp);
}
for(i = 0; i < plen; i += 2) {
lr[0] ^= streamtoword(data, doffp);
lr[1] ^= streamtoword(data, doffp);
this.encipher(lr, 0);
this.P[i] = lr[0];
this.P[i + 1] = lr[1];
}
for(i = 0; i < slen; i += 2) {
lr[0] ^= streamtoword(data, doffp);
lr[1] ^= streamtoword(data, doffp);
this.encipher(lr, 0);
this.S[i] = lr[0];
this.S[i + 1] = lr[1];
}
}
public byte[] crypt_raw(byte[] password, byte[] salt, int log_rounds, int[] cdata) {
int clen = cdata.length;
if (log_rounds >= 4 && log_rounds <= 30) {
int rounds = 1 << log_rounds;
if (salt.length != 16) {
throw new IllegalArgumentException("Bad salt length");
} else {
this.init_key();
this.ekskey(salt, password);
int i;
for(i = 0; i != rounds; ++i) {
this.key(password);
this.key(salt);
}
int j;
for(i = 0; i < 64; ++i) {
for(j = 0; j < clen >> 1; ++j) {
this.encipher(cdata, j << 1);
}
}
byte[] ret = new byte[clen * 4];
i = 0;
for(j = 0; i < clen; ++i) {
ret[j++] = (byte)(cdata[i] >> 24 & 255);
ret[j++] = (byte)(cdata[i] >> 16 & 255);
ret[j++] = (byte)(cdata[i] >> 8 & 255);
ret[j++] = (byte)(cdata[i] & 255);
}
return ret;
}
} else {
throw new IllegalArgumentException("Bad number of rounds");
}
}
public static String hashpw(String password, String salt) {
char minor = 0;
int off = false;
StringBuffer rs = new StringBuffer();
if (salt.charAt(0) == '$' && salt.charAt(1) == '2') {
byte off;
if (salt.charAt(2) == '$') {
off = 3;
} else {
minor = salt.charAt(2);
if (minor != 'a' || salt.charAt(3) != '$') {
throw new IllegalArgumentException("Invalid salt revision");
}
off = 4;
}
if (salt.charAt(off + 2) > '$') {
throw new IllegalArgumentException("Missing salt rounds");
} else {
int rounds = Integer.parseInt(salt.substring(off, off + 2));
String real_salt = salt.substring(off + 3, off + 25);
byte[] passwordb;
try {
passwordb = (password + (minor >= 'a' ? "\u0000" : "")).getBytes("UTF-8");
} catch (UnsupportedEncodingException var12) {
throw new AssertionError("UTF-8 is not supported");
}
byte[] saltb = decode_base64(real_salt, 16);
BCrypt B = new BCrypt();
byte[] hashed = B.crypt_raw(passwordb, saltb, rounds, (int[])((int[])bf_crypt_ciphertext.clone()));
rs.append("$2");
if (minor >= 'a') {
rs.append(minor);
}
rs.append("$");
if (rounds < 10) {
rs.append("0");
}
if (rounds > 30) {
throw new IllegalArgumentException("rounds exceeds maximum (30)");
} else {
rs.append(Integer.toString(rounds));
rs.append("$");
rs.append(encode_base64(saltb, saltb.length));
rs.append(encode_base64(hashed, bf_crypt_ciphertext.length * 4 - 1));
return rs.toString();
}
}
} else {
throw new IllegalArgumentException("Invalid salt version");
}
}
public static String gensalt(int log_rounds, SecureRandom random) {
StringBuffer rs = new StringBuffer();
byte[] rnd = new byte[16];
random.nextBytes(rnd);
rs.append("$2a$");
if (log_rounds < 10) {
rs.append("0");
}
if (log_rounds > 30) {
throw new IllegalArgumentException("log_rounds exceeds maximum (30)");
} else {
rs.append(Integer.toString(log_rounds));
rs.append("$");
rs.append(encode_base64(rnd, rnd.length));
return rs.toString();
}
}
public static String gensalt(int log_rounds) {
return gensalt(log_rounds, new SecureRandom());
}
public static String gensalt() {
return gensalt(10);
}
public static boolean checkpw(String plaintext, String hashed) {
byte[] hashed_bytes;
byte[] try_bytes;
try {
String try_pw = hashpw(plaintext, hashed);
hashed_bytes = hashed.getBytes("UTF-8");
try_bytes = try_pw.getBytes("UTF-8");
} catch (UnsupportedEncodingException var6) {
return false;
}
if (hashed_bytes.length != try_bytes.length) {
return false;
} else {
byte ret = 0;
for(int i = 0; i < try_bytes.length; ++i) {
ret = (byte)(ret | hashed_bytes[i] ^ try_bytes[i]);
}
return ret == 0;
}
}
}
总体来说，这种加密方式的有点
1. 登录密码进行加密后再存储到DB，即使被拖库，不会泄露密码，因为很多用户，在各个网站上为了密码易记忆，都是采用了同一个密码，那一个平台泄露，处处平台泄露极其不安全
2. 那简单的加密，比如对一个字符串N次加密，每次得到的密码是一致的，这种也不安全，用户多了你会发现，很多人的密码是一样的，比如我常见的密码12345，12qwaszx等等
3. 同样的密码， 需要加密后存储的值不一样，又能保证下次登录能够正确，BCrypt比其他加密方式多了一些thoughts
------------------------- A little Progress a day makes you a big success... ----------------------------
