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使用JVMTI實現(xiàn)SpringBoot的jar加密,防止反編譯

更新時間：2023年08月31日 15:06:24 作者：完美明天cxp

這篇文章主要介紹了使用JVMTI實現(xiàn)SpringBoot的jar加密,防止反編譯問題,具有很好的參考價值,希望對大家有所幫助,如有錯誤或未考慮完全的地方,望不吝賜教

1.背景

ToB項目私有化部署，攜帶有項目jar包，防止別人下載jar，反編譯出源碼

2.JVMTI解釋

JVMTI（Java Virtual Machine Tool Interface）即指 Java 虛擬機(jī)工具接口，它是一套由虛擬機(jī)直接提供的 native 接口，它處于整個 JPDA（Java Platform Debugger Architecture）體系的最底層，所有調(diào)試功能本質(zhì)上都需要通過 JVMTI 來提供。

通過這些接口，開發(fā)人員不僅調(diào)試在該虛擬機(jī)上運行的 Java 程序，還能查看它們運行的狀態(tài)，設(shè)置回調(diào)函數(shù)，控制某些環(huán)境變量，從而優(yōu)化程序性能。

3.使用JVMTI思路

在SpringBoot項目打包后，通過dll動態(tài)鏈接庫（so共享對象）加密生成新的jar，在啟動jar時，讓jvm啟動時調(diào)用jvmti提供的Agent_OnLoad方法，用c++去實現(xiàn)，去解密對應(yīng)的class文件。

利用c++編譯型語言特性，無法反編譯出對應(yīng)的加密解密方法。

4.實現(xiàn)源碼

c++加密實現(xiàn)和jvm啟動監(jiān)聽，需要jni.h，jvmti.h，jni_md.h三個頭文件，分別在java環(huán)境變量下include和include/linux（win32）下

// c++加密頭文件
#include <jni.h>
#ifndef _Included_com_cxp_demo_encrypt_ByteCodeEncryptor
#define _Included_com_cxp_demo_encrypt_ByteCodeEncryptor
#ifdef __cplusplus
extern "C"
{
#endif
    JNIEXPORT jbyteArray JNICALL Java_com_cxp_demo_encrypt_ByteCodeEncryptor_encrypt(JNIEnv *, jclass, jbyteArray);
#ifdef __cplusplus
}
#endif
#endif
#ifndef CONST_HEADER_H_  
#define CONST_HEADER_H_   
const int k = 4;
const int compare_length = 18;
const char* package_prefix= "com/cxp/demo";
#endif

// c++加密解密源碼
#include <iostream>
#include <jni.h>
#include <jvmti.h>
#include <jni_md.h>
#include "demo_bytecode_encryptor.h"
void encode(char *str)
{
    unsigned int m = strlen(str);
    for (int i = 0; i < m; i++)
    {
        str[i] = str[i] + k;
    }
}
void decode(char *str)
{
    unsigned int m = strlen(str);
    for (int i = 0; i < m; i++)
    {
        str[i] = str[i] - k;
    }
}
extern"C" JNIEXPORT jbyteArray JNICALL Java_com_cxp_demo_encrypt_ByteCodeEncryptor_encrypt(JNIEnv * env, jclass cla, jbyteArray text)
{
    char* dst = (char*)env->GetByteArrayElements(text, 0);
    encode(dst);
    env->SetByteArrayRegion(text, 0, strlen(dst), (jbyte *)dst);
    return text;
}
void JNICALL ClassDecryptHook(
    jvmtiEnv *jvmti_env,
    JNIEnv* jni_env,
    jclass class_being_redefined,
    jobject loader,
    const char* name,
    jobject protection_domain,
    jint class_data_len,
    const unsigned char* class_data,
    jint* new_class_data_len,
    unsigned char** new_class_data
)
{
    *new_class_data_len = class_data_len;
    jvmti_env->Allocate(class_data_len, new_class_data);
    unsigned char* _data = *new_class_data;
    if (name && strncmp(name, package_prefix, compare_length) == 0 && strstr(name, "BySpringCGLIB") == NULL)
    {
        for (int i = 0; i < class_data_len; i++)
        {
            _data[i] = class_data[i];
        }
        decode((char*)_data);
    }
    else {
        for (int i = 0; i < class_data_len; i++)
        {
            _data[i] = class_data[i];
        }
    }
}
JNIEXPORT jint JNICALL Agent_OnLoad(JavaVM *vm, char *options, void *reserved)
{
    jvmtiEnv *jvmti;
    jint ret = vm->GetEnv((void **)&jvmti, JVMTI_VERSION);
    if (JNI_OK != ret)
    {
        printf("ERROR: Unable to access JVMTI!\n");
        return ret;
    }
    jvmtiCapabilities capabilities;
    (void)memset(&capabilities, 0, sizeof(capabilities));
    capabilities.can_generate_all_class_hook_events = 1;
    capabilities.can_tag_objects = 1;
    capabilities.can_generate_object_free_events = 1;
    capabilities.can_get_source_file_name = 1;
    capabilities.can_get_line_numbers = 1;
    capabilities.can_generate_vm_object_alloc_events = 1;
    jvmtiError error = jvmti->AddCapabilities(&capabilities);
    if (JVMTI_ERROR_NONE != error)
    {
        printf("ERROR: Unable to AddCapabilities JVMTI!\n");
        return error;
    }
    jvmtiEventCallbacks callbacks;
    (void)memset(&callbacks, 0, sizeof(callbacks));
    callbacks.ClassFileLoadHook = &ClassDecryptHook;
    error = jvmti->SetEventCallbacks(&callbacks, sizeof(callbacks));
    if (JVMTI_ERROR_NONE != error)
    {
        printf("ERROR: Unable to SetEventCallbacks JVMTI!\n");
        return error;
    }
    error = jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_CLASS_FILE_LOAD_HOOK, NULL);
    if (JVMTI_ERROR_NONE != error)
    {
        printf("ERROR: Unable to SetEventNotificationMode JVMTI!\n");
        return error;
    }
    return JNI_OK;
}

java加密邏輯：

// JNI調(diào)用c++代碼
public class ByteCodeEncryptor {
    static {
        String currentPath = ByteCodeEncryptor.class.getResource("").getPath().split("SpringBootJarEncryptor.jar!")[0];
        if (currentPath.startsWith("file:")) {
            currentPath = currentPath.substring(5);
        }
        String dllPath;
        String os = System.getProperty("os.name");
        if (os.toLowerCase().startsWith("win")) {
            dllPath = currentPath + "SpringBootJarEncryptor.dll";
        } else {
            dllPath = currentPath + "SpringBootJarEncryptor.so";
        }
        System.load(dllPath);
    }
    public native static byte[] encrypt(byte[] text);
}

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.util.Enumeration;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;
import java.util.jar.JarOutputStream;
// 加密jar代碼
public class JarEncryptor {
    public static void encrypt(String fileName, String dstName) {
        try {
            ByteArrayOutputStream bos = new ByteArrayOutputStream();
            byte[] buf = new byte[1024];
            File srcFile = new File(fileName);
            File dstFile = new File(dstName);
            FileOutputStream dstFos = new FileOutputStream(dstFile);
            JarOutputStream dstJar = new JarOutputStream(dstFos);
            JarFile srcJar = new JarFile(srcFile);
            for (Enumeration<JarEntry> enumeration = srcJar.entries(); enumeration.hasMoreElements(); ) {
                JarEntry entry = enumeration.nextElement();
                InputStream is = srcJar.getInputStream(entry);
                int len;
                while ((len = is.read(buf, 0, buf.length)) != -1) {
                    bos.write(buf, 0, len);
                }
                byte[] bytes = bos.toByteArray();
                String name = entry.getName();
                if (name.startsWith("com/cxp/demo") && name.endsWith(".class")) {
                    try {
                        bytes = ByteCodeEncryptor.encrypt(bytes);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
                JarEntry ne = new JarEntry(name);
                dstJar.putNextEntry(ne);
                dstJar.write(bytes);
                bos.reset();
            }
            srcJar.close();
            dstJar.close();
            dstFos.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    public static void main(String[] args) {
        if (args == null || args.length == 0) {
            System.out.println("please input parameter");
            return;
        }
        if (args[0].endsWith(".jar")) {
            JarEncryptor.encrypt(args[0], args[0].substring(0, args[0].lastIndexOf(".")) + "_encrypted.jar");
        } else {
            File file = new File(args[0]);
            if (file.isDirectory()) {
                String[] list = file.list();
                if (list != null) {
                    for (String jarFilePath : list) {
                        if (jarFilePath.endsWith(".jar")) {
                            JarEncryptor.encrypt(args[0] + "/" + jarFilePath, args[0] + "_encrypted/" + jarFilePath);
                        }
                    }
                }
            } else {
                System.out.println("this is not a folder or folder is empty");
            }
        }
    }
}

實現(xiàn)步驟：

1.先把c++打成dll（so）動態(tài)鏈接庫

2.通過java調(diào)用dll文件，加密jar

3.啟動加密后的jar，加上啟動參數(shù)-agentpath:*.dll

gradle.build打包：

task copyJar(type: Copy) {
    delete "$buildDir/libs/lib"
    from configurations.runtime
    into "$buildDir/libs/lib"
}
jar {
    enabled = true
    dependsOn copyJar
    archivesBaseName = "app"
    archiveVersion = ""
    manifest {
        attributes 'Main-Class': "主類全限定名",
                'Class-Path': configurations.runtime.files.collect { "lib/$it.name" }.join(' ')
    }
}

Dockerfile文件：

# 加密jar
RUN mkdir ./build/libs/lib_encrypted
RUN java -jar ./encrypt/SpringBootJarEncryptor.jar ./build/libs/app.jar
RUN java -jar ./encrypt/SpringBootJarEncryptor.jar ./build/libs/lib
RUN rm -r ./build/libs/lib
RUN rm ./build/libs/app.jar
RUN mv ./build/libs/lib_encrypted ./build/libs/lib
RUN mv ./build/libs/app_encrypted.jar ./build/libs/app.jar
# --- java ---
FROM java8
# 提取啟動需要的資源
COPY --from=builder /build/libs/app.jar /application/app.jar
COPY --from=builder /build/libs/lib /application/lib
COPY --from=builder /encrypt /encrypt
COPY --from=builder /start.sh start.sh
ENTRYPOINT ["sh", "start.sh"]

啟動命令：

java -agentpath:./SpringBootJarEncryptor.dll -jar app.jar

5.踩坑

java使用jni調(diào)用c++函數(shù)，c++被調(diào)用的函數(shù)名要與java方法全限定名一致，如：com.cxp.demo.encrypt.ByteCodeEncryptor#encrypt=》Java_com_cxp_demo_encrypt_ByteCodeEncryptor_encrypt，注意java和c++數(shù)據(jù)類型的對應(yīng)關(guān)系

JVMTI只能作用Java原生啟動類加載器，而SpringBoot有自己啟動類加載器，讀取SpringBoot規(guī)定的原文件路徑（BOOT-INF/classes）和依賴路徑（BOOT-INF/lib），所以SpringBoot要打包成普通jar方式，bootjar是SpringBoot默認(rèn)的打包方式，改為jar打包方式無法打入依賴包，只能把依賴包打到同文件夾下，修改MANIFEST.MF文件的CLass-Path屬性，把依賴包添加進(jìn)去。可以看下SpringBoot的啟動jar和普通jar區(qū)別。

c++在linux下打成so庫，可以自行搜索下，推薦使用cmake

java引入dll動態(tài)庫，只能放在java的classpath下或絕對路徑

引包方式改為可以打出依賴包的方式，如compile，運行時不需要的可以不用