伪加密的apk有那么难么？了解原理就没啥可怕的。放出java代码，python的早就有了。
package com.rover12421.apkutil;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.util.Arrays;
import java.util.zip.ZipError;
import static com.rover12421.apkutil.ZipConstants.*;
public class ApkUtilTool {
private FileChannel ch; // channel to the zipfile
private FileChannel fc;
/**
* 修复zip伪加密状态的Entry
* @param inZip
* @param storeZip
* @throws IOException
*/
public void FixEncryptedEntry(File inZip, File fixZip) throws IOException {
changEntry(inZip, fixZip, true);
}
/**
* 修复zip伪加密状态的Entry
* @param inZip
* @param storeZip
* @throws IOException
*/
public void FixEncryptedEntry(String inZip, String fixZip) throws IOException {
FixEncryptedEntry(new File(inZip), new File(fixZip));
}
/**
* 修改zip的Entry为伪加密状态
* @param inZip
* @param storeZip
* @throws IOException
*/
public void ChangToEncryptedEntry(File inZip, File storeZip) throws IOException {
changEntry(inZip, storeZip, false);
}
/**
* 修改zip的Entry为伪加密状态
* @param inZip
* @param storeZip
* @throws IOException
*/
public void ChangToEncryptedEntry(String inZip, String storeZip) throws IOException {
ChangToEncryptedEntry(new File(inZip), new File(storeZip));
}
/**
* 更改zip的Entry为伪加密状态
* @param inZip
* @param storeZip
* @param fix ture:修复伪加密 false:更改到伪加密
* @throws IOException
*/
private void changEntry(File inZip, File storeZip, boolean fix) throws IOException {
FileInputStream fis = new FileInputStream(inZip);
FileOutputStream fos = new FileOutputStream(storeZip);
byte[] buf = new byte[10240];
int len;
while ((len = fis.read(buf)) != -1) {
fos.write(buf, 0, len);
}
ch = fis.getChannel();
fc = fos.getChannel();
changEntry(fix);
ch.close();
fc.close();
fis.close();
fos.close();
}
// Reads zip file central directory. Returns the file position of first
// CEN header, otherwise returns -1 if an error occured. If zip->msg != NULL
// then the error was a zip format error and zip->msg has the error text.
// Always pass in -1 for knownTotal; it's used for a recursive call.
private void changEntry(boolean fix) throws IOException {
END end = findEND();
if (end.cenlen > end.endpos)
zerror("invalid END header (bad central directory size)");
long cenpos = end.endpos - end.cenlen; // position of CEN table
// Get position of first local file (LOC) header, taking into
// account that there may be a stub prefixed to the zip file.
long locpos = cenpos - end.cenoff;
if (locpos < 0)
zerror("invalid END header (bad central directory offset)");
// read in the CEN and END
byte[] cen = new byte[(int)(end.cenlen + ENDHDR)];
if (readFullyAt(cen, 0, cen.length, cenpos) != end.cenlen + ENDHDR) {
zerror("read CEN tables failed");
}
int pos = 0;
int limit = cen.length - ENDHDR;
while (pos < limit) {
if (CENSIG(cen, pos) != CENSIG)
zerror("invalid CEN header (bad signature)");
int method = CENHOW(cen, pos);
int nlen = CENNAM(cen, pos);
int elen = CENEXT(cen, pos);
int clen = CENCOM(cen, pos);
if (fix) {
if ((CEN***(cen, pos) & 1) != 0) {
byte[] name = Arrays.copyOfRange(cen, pos + CENHDR, pos + CENHDR + nlen);
System.out.println("Found the encrypted entry : " + new String(name) + ", fix...");
//b[n] & 0xff) | ((b[n + 1] & 0xff) << 8
cen[pos+8] &= 0xFE;
// cen[pos+8] ^= CEN***(cen, pos) % 2;
// cen[pos+8] ^= cen[pos+8] % 2;
// zerror("invalid CEN header (encrypted entry)");
}
} else {
if ((CEN***(cen, pos) & 1) == 0) {
byte[] name = Arrays.copyOfRange(cen, pos + CENHDR, pos + CENHDR + nlen);
System.out.println("Chang the entry : " + new String(name) + ", Encrypted...");
//b[n] & 0xff) | ((b[n + 1] & 0xff) << 8
cen[pos+8] |= 0x1;
// zerror("invalid CEN header (encrypted entry)");
}
}
if (method != METHOD_STORED && method != METHOD_DEFLATED)
zerror("invalid CEN header (unsupported compression method: " + method + ")");
if (pos + CENHDR + nlen > limit)
zerror("invalid CEN header (bad header size)");
// skip ext and comment
pos += (CENHDR + nlen + elen + clen);
}
writeFullyAt(cen, 0, cen.length, cenpos);
if (pos + ENDHDR != cen.length) {
zerror("invalid CEN header (bad header size)");
}
}
// Reads len bytes of data from the specified offset into buf.
// Returns the total number of bytes read.
// Each/every byte read from here (except the cen, which is mapped).
final long readFullyAt(byte[] buf, int off, long len, long pos)
throws IOException
{
ByteBuffer bb = ByteBuffer.wrap(buf);
bb.position(off);
bb.limit((int)(off + len));
return readFullyAt(bb, pos);
}
private final long readFullyAt(ByteBuffer bb, long pos)
throws IOException
{
synchronized(ch) {
return ch.position(pos).read(bb);
}
}
final long writeFullyAt(byte[] buf, int off, long len, long pos)
throws IOException
{
ByteBuffer bb = ByteBuffer.wrap(buf);
bb.position(off);
bb.limit((int)(off + len));
return writeFullyAt(bb, pos);
}
private final long writeFullyAt(ByteBuffer bb, long pos)
throws IOException
{
synchronized(fc) {
return fc.position(pos).write(bb);
}
}
// Searches for end of central directory (END) header. The contents of
// the END header will be read and placed in endbuf. Returns the file
// position of the END header, otherwise returns -1 if the END header
// was not found or an error occurred.
private END findEND() throws IOException
{
byte[] buf = new byte[READBLOCKSZ];
long ziplen = ch.size();
long minHDR = (ziplen - END_MAXLEN) > 0 ? ziplen - END_MAXLEN : 0;
long minPos = minHDR - (buf.length - ENDHDR);
for (long pos = ziplen - buf.length; pos >= minPos; pos -= (buf.length - ENDHDR))
{
int off = 0;
if (pos < 0) {
// Pretend there are some NUL bytes before start of file
off = (int)-pos;
Arrays.fill(buf, 0, off, (byte)0);
}
int len = buf.length - off;
if (readFullyAt(buf, off, len, pos + off) != len)
zerror("zip END header not found");
// Now scan the block backwards for END header signature
for (int i = buf.length - ENDHDR; i >= 0; i--) {
if (buf[i+0] == (byte)'P' &&
buf[i+1] == (byte)'K' &&
buf[i+2] == (byte)'\005' &&
buf[i+3] == (byte)'\006' &&
(pos + i + ENDHDR + ENDCOM(buf, i) == ziplen)) {
// Found END header
buf = Arrays.copyOfRange(buf, i, i + ENDHDR);
END end = new END();
end.endsub = ENDSUB(buf);
end.centot = ENDTOT(buf);
end.cenlen = ENDSIZ(buf);
end.cenoff = ENDOFF(buf);
end.comlen = ENDCOM(buf);
end.endpos = pos + i;
if (end.cenlen == ZIP64_MINVAL ||
end.cenoff == ZIP64_MINVAL ||
end.centot == ZIP64_MINVAL32)
{
// need to find the zip64 end;
byte[] loc64 = new byte[ZIP64_LOCHDR];
if (readFullyAt(loc64, 0, loc64.length, end.endpos - ZIP64_LOCHDR)
!= loc64.length) {
return end;
}
long end64pos = ZIP64_LOCOFF(loc64);
byte[] end64buf = new byte[ZIP64_ENDHDR];
if (readFullyAt(end64buf, 0, end64buf.length, end64pos)
!= end64buf.length) {
return end;
}
// end64 found, re-calcualte everything.
end.cenlen = ZIP64_ENDSIZ(end64buf);
end.cenoff = ZIP64_ENDOFF(end64buf);
end.centot = (int)ZIP64_ENDTOT(end64buf); // assume total < 2g
end.endpos = end64pos;
}
return end;
}
}
}
zerror("zip END header not found");
return null; //make compiler happy
}
static void zerror(String msg) {
throw new ZipError(msg);
}
// End of central directory record
static class END {
int disknum;
int sdisknum;
int endsub; // endsub
int centot; // 4 bytes
long cenlen; // 4 bytes
long cenoff; // 4 bytes
int comlen; // comment length
byte[] comment;
/* members of Zip64 end of central directory locator */
int diskNum;
long endpos;
int disktot;
@Override
public String toString() {
return "disknum : " + disknum + "\n" +
"sdisknum : " + sdisknum + "\n" +
"endsub : " + endsub + "\n" +
"centot : " + centot + "\n" +
"cenlen : " + cenlen + "\n" +
"cenoff : " + cenoff + "\n" +
"comlen : " + comlen + "\n" +
"diskNum : " + diskNum + "\n" +
"endpos : " + endpos + "\n" +
"disktot : " + disktot;
}
}
}
[招生]科锐逆向工程师培训(2024年11月15日实地，远程教学同时开班, 第51期)
