安卓逆向中常见的加密算法
1、接口中的方法
根据调用关系，找到接口中的方法。
interface IRequest{
public void send(String url);
}
class Context{
public IRequest req;
public Context(IRequest req){
this.req = req;
}
public void doRequest(){
String url = "/click/android2/"
this.req.send(url);
}
}
public class Hello{
public static void main(String[] args){
}
}当我们通过关键字"/click/android2/"定位到了13行doRequest方法中，可以发现调用了接口中的send方法，我们可以从两个方面去思考：
- 思路1：寻找实现了IRequest接口的类
- 思路2：谁传入的req？
2、隐藏的字节
注意：一个汉字表示3个字节
String v4 = new String(new byte[]{-26, -83, -90, -26, -78, -101, -23, -67, -112});3、UUID
import java.util.UUID;
public class Hello{
public static void main(String[] args){
String uid = UUID.randomUUID().toString();
System.out.println(uid);
}
}4、随机值
import java.math.BigInteger;
import java.security.SecureRandom;
public class Hello{
public static void main(String[] args){
// 随机生成80位，10个字节
BigInteger v4 = new BigInteger(80, new SecureRandom());
// 让字节以16进制展示
String res = v4.toString(16);
System.out.println(res);
}
}在python中表示：
import random
# python中的16进制会有0x前缀，所以使用切片[2:]
open_udid = "".join([hex(i)[2:] for i in random.randbytes(10)])
print(open_udid)5、时间戳
public class Hello{
public static void main(String[] args){
// 生成秒级别
String t1 = String valueOf(System.currentTimeMillis() / 1000);
// 生成毫秒级别
String t2 = String valueOf(System.currentTimeMillis());
System.out.println(t1);
System.out.println(t2);
}
}6、十六进制字符串
import java.util.Arrays;
public class Hello {
public static void main(String[] args) {
String name = "小猪佩奇";
byte[] nameBytes = name.getBytes();
// [-27, -80, -113, -25, -116, -86, -28, -67, -87, -27, -91, -121]
System.out.println(Arrays.toString(nameBytes));
StringBuilder sb = new StringBuilder();
for(int i = 0;i < nameBytes.length; i++){
int val = nameBytes[i] & 255; // 负数转化为正数
if(val < 16){
sb.append("0");
}
sb.append(Integer.toHexString(val));
}
String res = sb.toString(); // e5b08fe78caae4bda9e5a587
System.out.println(res);
}
}使用python实现：
name = "小猪佩奇"
data_list = []
for item in name.encode('utf-8'):
val = hex(item) # 将字节转化为16进制
data = val[2:].zfill(2) # 去掉前缀0x, 不足两位的补上
data_list.append(data)
result = ''.join(data_list)
print(result)七、base64
import java.util.Base64;
public class base64 {
public static void main(String[] args) {
String name = "小猪佩奇";
// 加密
Base64.Encoder encoder = Base64.getEncoder();
String res = encoder.encodeToString(name.getBytes());
System.out.println(res); // 5bCP54yq5L2p5aWH
// 解密
Base64.Decoder decoder = Base64.getDecoder();
byte[] origin = decoder.decode(res);
String data = new String(origin);
System.out.println(data);
}
}
用python实现：
import base64
name = "小猪佩奇"
# 加密
res = base64.b64encode(name.encode('utf-8')).decode('utf-8')
# 解密
print(base64.b64decode(res.encode('utf-8')).decode('utf-8'))八、md5加密
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
public class base64 {
public static void main(String[] args) throws NoSuchAlgorithmException {
String name = "小猪佩奇";
MessageDigest instance = MessageDigest.getInstance("MD5");
instance.update("xxxxxx".getBytes()); // 加盐
byte[] nameBytes = instance.digest(name.getBytes()); // 返回字节数组
System.out.println(Arrays.toString(nameBytes));
String res = new String(nameBytes);
System.out.println(res);
// 十六进制展示
StringBuilder sb = new StringBuilder();
for(int i = 0;i < nameBytes.length; i++){
int val = nameBytes[i] & 255;
if(val < 16){
sb.append("0");
}
sb.append(Integer.toHexString(val));
}
String hexData = sb.toString();
System.out.println(hexData);
}
}
用python表示为：
from hashlib import md5
name = "小猪佩奇"
obj = md5()
obj.update(name.encode('utf-8'))
res = obj.digest() # 返回字节字符串
print(res)
res = obj.hexdigest() # 返回的是16进制字节字符串
print(res)九、sha-256加密
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
public class base64 {
public static void main(String[] args) throws NoSuchAlgorithmException {
String name = "小猪佩奇";
MessageDigest instance = MessageDigest.getInstance("sha-256");
instance.update("xxxxxx".getBytes()); // 加盐
byte[] nameBytes = instance.digest(name.getBytes()); // 返回字节数组
System.out.println(Arrays.toString(nameBytes));
String res = new String(nameBytes);
System.out.println(res);
// 十六进制展示
StringBuilder sb = new StringBuilder();
for(int i = 0;i < nameBytes.length; i++){
int val = nameBytes[i] & 255;
if(val < 16){
sb.append("0");
}
sb.append(Integer.toHexString(val));
}
String hexData = sb.toString();
System.out.println(hexData);
}
}
用python表示为：
from hashlib import md5
name = "小猪佩奇"
obj = md5()
obj.update(name.encode('utf-8'))
res = obj.digest() # 返回字节字符串
print(res)
res = obj.hexdigest() # 返回的是16进制字节字符串
print(res)十、aes加密
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
public class base64 {
public static void main(String[] args) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidAlgorithmParameterException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
String name = "小猪佩奇";
String key = "fd6b639dbcff0c2a1b03b389ec763c4b";
String iv = "77b07a672d57d64c";
// 加密
byte[] raw = key.getBytes();
SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
IvParameterSpec ivSpec = new IvParameterSpec(iv.getBytes());
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, skeySpec, ivSpec);
byte[] encrypted = cipher.doFinal(name.getBytes());
System.out.println(Arrays.toString(encrypted));
}
}
用python表示为：
from Crypto.Cipher import AES
from Crypto.Util.Padding import pad
name = "小猪佩奇"
key = "fd6b639dbcff0c2a1b03b389ec763c4b"
iv = "77b07a672d57d64c"
aes = AES.new(key=key.encode('utf-8'), iv=iv.encode('utf-8'), mode=AES.MODE_CBC)
name = pad(name.encode('utf-8'), 16)
res = aes.encrypt(name)
print(res)十一、gzip压缩
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.Arrays;
import java.util.zip.GZIPInputStream;
import java.util.zip.GZIPOutputStream;
public class base64 {
public static void main(String[] args) throws IOException {
// 压缩
String name = "小猪佩奇";
ByteArrayOutputStream v0_1 = new ByteArrayOutputStream();
GZIPOutputStream v1 = new GZIPOutputStream((v0_1));
v1.write(name.getBytes());
v1.close();
byte[] arg6 = v0_1.toByteArray(); // gzip压缩后
System.out.println(Arrays.toString(arg6));
// 解压缩
ByteArrayOutputStream out = new ByteArrayOutputStream();
ByteArrayInputStream in = new ByteArrayInputStream(arg6);
GZIPInputStream ungzip = new GZIPInputStream(in);
byte[] buffer = new byte[256];
int n;
while((n = ungzip.read(buffer)) >= 0){
out.write(buffer, 0, n);
}
byte[] res = out.toByteArray();
System.out.println(out.toString("utf-8"));
}
}
用python表示为：
import gzip
# 压缩
name = "小猪佩奇"
s_in = name.encode("utf-8")
s_out = gzip.compress(s_in)
print([i for i in s_out])
# 解压缩
res = gzip.decompress(s_out)
print(res)
print(res.decode('utf-8'))