更详细的解释可以下载我的 “密码”文件
public class IDEA {
private byte[] bytekey;
public byte[] getKey(String key) {
int len1 = key.length();
if (len1 >= 16) {
key = key.substring(0,16);
} else {
for (int i = 0; i < 16 - len1; i++) {
key = key.concat("0");
}
}
bytekey = key.getBytes();
return bytekey;
}
/** 加密String明文输入,String密文输出 */
public String getEncString(String strMing) {
byte[] byteMinull;
byte[] byteMingnull;
String strMi = "";
try {
return byte2hex(IdeaEncrypt(bytekey, strMing.getBytes(), true));
} catch (Exception e) {
e.printStackTrace();
} finally {
byteMing = null;
byteMi = null;
}
return strMi;
}
/** 解密 以String密文输入,String明文输出*/
public String getDesString(String strMi) {
byte[] byteMingnull;
byte[] byteMinull;
String strMing = "";
try {
String tmp = new String(IdeaEncrypt(bytekey, hex2byte(strMi
.getBytes()), false));
int len1 = tmp.length();
return tmp.substring(0, len1 - 6);
} catch (Exception e) {
e.printStackTrace();
} finally {
byteMing = null;
byteMi = null;
}
return strMing;
}
private byte[] Encrypt(byte[] bytekey, byte[] inputBytes, boolean flag) {
byte[] encryptCode = new byte[8];
int[] key = get_subkey(flag, bytekey);// 分解子密钥
encrypt(key, inputBytes, encryptCode);// 进行加密操作
return encryptCode;// 返回加密数据
}
private int bytesToInt(byte[] inBytes, int startPos) {
return ((inBytes[startPos] << 8) & 0xff00)
+ (inBytes[startPos + 1] & 0xff);
}
private void intToBytes(int inputInt, byte[] outBytes, int startPos) {
outBytes[startPos] = (byte) (inputInt >>> 8);
outBytes[startPos + 1] = (byte) inputInt;
}
private int x_multiply_y(int x, int y) {
if (x == 0) {
x = 0x10001 - y;
} else if (y == 0) {
x = 0x10001 - x;
} else {
int tmp = x * y;
y = tmp & 0xffff;
x = tmp >>> 16;
x = (y - x) + ((y < x) ? 1 : 0);
}
return x & 0xffff;
}
/** 加密函数*/
private void encrypt(int[] key, byte[] inbytes, byte[] outbytes) {
int k = 0;
int a = bytesToInt(inbytes, 0);
int b = bytesToInt(inbytes, 2);
int c = bytesToInt(inbytes, 4);
int d = bytesToInt(inbytes, 6);
for (int i = 0; i < 8; i++) {
a = x_multiply_y(a, key[k++]);
b += key[k++];
b &= 0xffff;
c += key[k++];
c &= 0xffff;
d = x_multiply_y(d, key[k++]);
int tmp1 = b;
int tmp2 = c;
c ^= a;
b ^= d;
c = x_multiply_y(c, key[k++]);
b += c;
b &= 0xffff;
b = x_multiply_y(b, key[k++]);
c += b;
c &= 0xffff;
a ^= b;
d ^= c;
b ^= tmp2;
c ^= tmp1;
}
intToBytes(x_multiply_y(a, key[k++]), outbytes, 0);
intToBytes(c + key[k++], outbytes, 2);
intToBytes(b + key[k++], outbytes, 4);
intToBytes(x_multiply_y(d, key[k]), outbytes, 6);
}
private int[] encrypt_subkey(byte[] byteKey) {
int[] key = new int[52];
if (byteKey.length < 16) {
byte[] tmpkey = new byte[16];
System.arraycopy(byteKey, 0, tmpkey,
tmpkey.length - byteKey.length, byteKey.length);
byteKey = tmpkey;
}
for (int i = 0; i < 8; i++) {
key[i] = bytesToInt(byteKey, i * 2);
}
for (int j = 8; j < 52; j++) {
if ((j & 0x7) < 6) {
key[j] = (((key[j - 7] & 0x7f) << 9) | (key[j - 6] >> 7)) & 0xffff;
} else if ((j & 0x7) == 6) {
key[j] = (((key[j - 7] & 0x7f) << 9) | (key[j - 14] >> 7)) & 0xffff;
} else {
key[j] = (((key[j - 15] & 0x7f) << 9) | (key[j - 14] >> 7)) & 0xffff;
}
}
return key;
}
private int fun_a(int a) {
if (a < 2) {
return a;
}
int b = 1;
int c = 0x10001 / a;
for (int i = 0x10001 % a; i != 1;) {
int d = a / i;
a %= i;
b = (b + (c * d)) & 0xffff;
if (a == 1) {
return b;
}
d = i / a;
i %= a;
c = (c + (b * d)) & 0xffff;
}
return (1 - c) & 0xffff;
}
private int fun_b(int b) {
return (0 - b) & 0xffff;
}
private int[] uncrypt_subkey(int[] key) {
int dec = 52;
int asc = 0;
int[] unkey = new int[52];
int aa = fun_a(key[asc++]);
int bb = fun_b(key[asc++]);
int cc = fun_b(key[asc++]);
int dd = fun_a(key[asc++]);
unkey[--dec] = dd;
unkey[--dec] = cc;
unkey[--dec] = bb;
unkey[--dec] = aa;
for (int k1 = 1; k1 < 8; k1++) {
aa = key[asc++];
bb = key[asc++];
unkey[--dec] = bb;
unkey[--dec] = aa;
aa = fun_a(key[asc++]);
bb = fun_b(key[asc++]);
cc = fun_b(key[asc++]);
dd = fun_a(key[asc++]);
unkey[--dec] = dd;
unkey[--dec] = bb;
unkey[--dec] = cc;
unkey[--dec] = aa;
}
aa = key[asc++];
bb = key[asc++];
unkey[--dec] = bb;
unkey[--dec] = aa;
aa = fun_a(key[asc++]);
bb = fun_b(key[asc++]);
cc = fun_b(key[asc++]);
dd = fun_a(key[asc]);
unkey[--dec] = dd;
unkey[--dec] = cc;
unkey[--dec] = bb;
unkey[--dec] = aa;
return unkey;
}
private int[] get_subkey(boolean flag, byte[] bytekey) {
if (flag) {
return encrypt_subkey(bytekey);
} else {
return uncrypt_subkey(encrypt_subkey(bytekey));
}
}
private byte[] ByteDataFormat(byte[] data, int unit) {
int len = data.length;
int padlen = unit - (len % unit);
int newlen = len + padlen;
byte[] newdata = new byte[newlen];
System.arraycopy(data, 0, newdata, 0, len);
for (int i = len; i < newlen; i++)
newdata[i] = (byte) padlen;
return newdata;
}
public byte[] IdeaEncrypt(byte[] idea_key, byte[] idea_data, boolean flag) {
byte[] format_key = ByteDataFormat(idea_key, 16);
byte[] format_data = ByteDataFormat(idea_data, 8);
int datalen = format_data.length;
int unitcount = datalen / 8;
byte[] result_data = new byte[datalen];
for (int i = 0; i < unitcount; i++) {
byte[] tmpkey = new byte[16];
byte[] tmpdata = new byte[8];
System.arraycopy(format_key, 0, tmpkey, 0, 16);
System.arraycopy(format_data, i * 8, tmpdata, 0, 8);
byte[] tmpresult = Encrypt(tmpkey, tmpdata, flag);
System.arraycopy(tmpresult, 0, result_data, i * 8, 8);
}
return result_data;
}
/**二行制转字符串*/
public static String byte2hex(byte[] b) { // 一个字节的数，
// 转成16进制字符串
String hs = "";
String stmp = "";
for (int n = 0; n < b.length; n++) {
stmp = (java.lang.Integer.toHexString(b[n] & 0XFF));
// 整数转成十六进制表示
if (stmp.length() == 1)
hs = hs + "0" + stmp;
else
hs = hs + stmp;
}
return hs.toUpperCase(); // 转成大写
}
public static byte[] hex2byte(byte[] b) {
if ((b.length % 2) != 0)
throw new IllegalArgumentException("长度不是偶数");
byte[] b2 = new byte[b.length / 2];
for (int n = 0; n < b.length; n += 2) {
String item = new String(b, n, 2);
// 两位一组，表示一个字节,把这样表示的16进制字符串，还原成一个进制字节
b2[n / 2] = (byte) Integer.parseInt(item, 16);
}
return b2;
}
public static void main(String[] args) {
IDEA idea = new IDEA();
idea.getKey("1234");//生成密匙
String strEnc = idea.getEncString("yushiwei");//加密字符串,返回String的密文
System.out.println("密文为：");
System.out.println(strEnc);
String strDes = idea.getDesString(strEnc);//把String 类型的密文解密
System.out.println("明文为：");
System.out.println(strDes);
}
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