解密
目前可用的加密版本有Delphi, VB, C++, C#，比较简单，直接移植为JAVA语法就可以了
C#移植过来的版本：
public static byte[] Base64Decode(byte[] source) 
{
byte[] a1, a2;
a1 = source;
a2 = new byte[a1.length * 3 / 4];
for (int i = 0; i < a1.length; i++) {
a1[i] = (byte) (a1[i] - 0x3c);
}
for (int i = 0, k = a1.length / 4; i < k; i++) {
a2[i * 3] = (byte) ((byte) (a1[i * 4] << 2) + (byte) (a1[i * 4 + 1] >> 4));
a2[i * 3 + 1] = (byte) ((byte) (a1[i * 4 + 1] << 4) + (byte) (a1[i * 4 + 2] >> 2));
a2[i * 3 + 2] = (byte) ((byte) (a1[i * 4 + 2] << 6) + a1[i * 4 + 3]);
}
if (a2.length % 3 == 2) {
a2[a2.length - 2] = (byte) ((byte) (a1[a1.length - 3] << 2) + (byte) (a1[a1.length - 2] >> 4));
a2[a2.length - 1] = (byte) ((byte) (a1[a1.length - 2] << 4) + (byte) (a1[a1.length - 1] >> 2));
} else if (a2.length % 3 == 1)
a2[a2.length - 1] = (byte) ((byte) (a1[a1.length - 2] << 2) + (byte) (a1[a1.length - 1] >> 4));
return a2;
}
C++移植过来的代码:
public static byte[] fnDecode6BitBuf(byte[] source) {
byte[] pszSrc = source;
byte[] pszDest = new byte[pszSrc.length * 3 / 4];
int nDestLen = pszDest.length;
int nLen = pszSrc.length;
int nDestPos = 0;
int nBitPos = 2;
int nMadeBit = 0;
byte ch;
byte chCode;
byte tmp = 0;
for (int i = 0; i < nLen; i++) {
if ((pszSrc[i] - 0x3c) >= 0)
ch = (byte) (pszSrc[i] - 0x3c);
else {
nDestPos = 0;
break;
}
if (nDestPos >= nDestLen)
break;
if ((nMadeBit + 6) >= 8) {
chCode = (byte) (tmp | ((ch & 0x3f) >> (6 - nBitPos)));
pszDest[nDestPos++] = (byte) chCode;
nMadeBit = 0;
if (nBitPos < 6)
nBitPos += 2;
else {
nBitPos = 2;
continue;
}
}
tmp = (byte) ((ch << nBitPos) & decode6BitMask[nBitPos - 2]);
nMadeBit += (8 - nBitPos);
}
return pszDest;
}
解密
解密的版本也是众多，但是均不可直接移植，java的byte范围最大只支持到128，超过128则取反（负），位移运算时需要考虑到补码，C#或C++的版本中的位运算将不能正确解密
以下是JAVA的解密方法
public static byte[] Base64Encode(byte[] source) {
byte[] a1, a2;
a1 = source;
if (a1.length % 3 == 0)
a2 = new byte[a1.length * 4 / 3];
else
a2 = new byte[a1.length * 4 / 3 + 1];
for (int i = 0, k = a1.length / 3; i < k; i++) {
a2[i * 4] = (byte) (((a1[i * 3] >> 2) & 0x3F) + 0x3c);
a2[i * 4 + 1] = (byte) (((((a1[i * 3] << 4) & 0x3f)) | ((a1[i * 3 + 1] >> 4) & 0x0f)) + 0x3c);
a2[i * 4 + 2] = (byte) ((((a1[i * 3 + 1] << 2) & 0x3f) | ((a1[i * 3 + 2] >> 6) & 0x03)) + 0x3c);
a2[i * 4 + 3] = (byte) ((a1[i * 3 + 2] & 0x3f) + 0x3c);
}
if (a1.length % 3 == 1){
a2[a2.length - 2] = (byte) (((a1[a1.length - 1] >> 2) & 0x3F) + 0x3c);
a2[a2.length - 1] = (byte) (((a1[a1.length - 1] << 4) & 0x3F) + 0x3c);
}
else if (a1.length % 3 == 2)
a2[a2.length - 1] = (byte) ((byte) (a1[a1.length - 1] << 4) >> 2);
for (int i = 0; i < a2.length; i++) {
System.out.println("a2["+i+"] - "+a2[i]);
}
return a2;
}
数据结构
typedef struct tag_TDEFAULTMESSAGE
{
int nRecog;
WORD wIdent;
WORD wParam;
WORD wTag;
WORD wSeries;
} _TDEFAULTMESSAGE, *_LPTDEFAULTMESSAGE;
这是前12个字节的结构定义，字节数分别为 4,2,2,2,2，分别对应封包的前12个字节
从后往前的顺序重排字节组成对应数据，例如下面代码获得 nRecog
nRecogBuffer.append(PacketEncode.byte2Hex(commandByte[3]));
nRecogBuffer.append(PacketEncode.byte2Hex(commandByte[2]));
nRecogBuffer.append(PacketEncode.byte2Hex(commandByte[1]));
nRecogBuffer.append(PacketEncode.byte2Hex(commandByte[0]));
posted on 2008-05-19 20:44
Phrancol Yang 阅读(455)
评论(0) 编辑 收藏 所属分类:
反汇编