二、OpenSSL 开源库解密参考代码
OpenSSL 加密解密代码参考 OpenSSL 源码跟目录下 demos/evp/aesccm.c 官方示例代码 , 在 Android 的 jni 代码中按照下面示例代码中的 aes_ccm_decrypt 方法解密即可 ;
/* * Simple AES CCM test program, uses the same NIST data used for the FIPS * self test but uses the application level EVP APIs. */ #include <stdio.h> #include <openssl/bio.h> #include <openssl/evp.h> /* AES-CCM test data from NIST public test vectors */ static const unsigned char ccm_key[] = { 0xce, 0xb0, 0x09, 0xae, 0xa4, 0x45, 0x44, 0x51, 0xfe, 0xad, 0xf0, 0xe6, 0xb3, 0x6f, 0x45, 0x55, 0x5d, 0xd0, 0x47, 0x23, 0xba, 0xa4, 0x48, 0xe8 }; static const unsigned char ccm_nonce[] = { 0x76, 0x40, 0x43, 0xc4, 0x94, 0x60, 0xb7 }; static const unsigned char ccm_adata[] = { 0x6e, 0x80, 0xdd, 0x7f, 0x1b, 0xad, 0xf3, 0xa1, 0xc9, 0xab, 0x25, 0xc7, 0x5f, 0x10, 0xbd, 0xe7, 0x8c, 0x23, 0xfa, 0x0e, 0xb8, 0xf9, 0xaa, 0xa5, 0x3a, 0xde, 0xfb, 0xf4, 0xcb, 0xf7, 0x8f, 0xe4 }; static const unsigned char ccm_pt[] = { 0xc8, 0xd2, 0x75, 0xf9, 0x19, 0xe1, 0x7d, 0x7f, 0xe6, 0x9c, 0x2a, 0x1f, 0x58, 0x93, 0x9d, 0xfe, 0x4d, 0x40, 0x37, 0x91, 0xb5, 0xdf, 0x13, 0x10 }; static const unsigned char ccm_ct[] = { 0x8a, 0x0f, 0x3d, 0x82, 0x29, 0xe4, 0x8e, 0x74, 0x87, 0xfd, 0x95, 0xa2, 0x8a, 0xd3, 0x92, 0xc8, 0x0b, 0x36, 0x81, 0xd4, 0xfb, 0xc7, 0xbb, 0xfd }; static const unsigned char ccm_tag[] = { 0x2d, 0xd6, 0xef, 0x1c, 0x45, 0xd4, 0xcc, 0xb7, 0x23, 0xdc, 0x07, 0x44, 0x14, 0xdb, 0x50, 0x6d }; void aes_ccm_encrypt(void) { EVP_CIPHER_CTX *ctx; int outlen, tmplen; unsigned char outbuf[1024]; printf("AES CCM Encrypt:\n"); printf("Plaintext:\n"); BIO_dump_fp(stdout, ccm_pt, sizeof(ccm_pt)); ctx = EVP_CIPHER_CTX_new(); /* Set cipher type and mode */ EVP_EncryptInit_ex(ctx, EVP_aes_192_ccm(), NULL, NULL, NULL); /* Set nonce length if default 96 bits is not appropriate */ EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, sizeof(ccm_nonce), NULL); /* Set tag length */ EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, sizeof(ccm_tag), NULL); /* Initialise key and IV */ EVP_EncryptInit_ex(ctx, NULL, NULL, ccm_key, ccm_nonce); /* Set plaintext length: only needed if AAD is used */ EVP_EncryptUpdate(ctx, NULL, &outlen, NULL, sizeof(ccm_pt)); /* Zero or one call to specify any AAD */ EVP_EncryptUpdate(ctx, NULL, &outlen, ccm_adata, sizeof(ccm_adata)); /* Encrypt plaintext: can only be called once */ EVP_EncryptUpdate(ctx, outbuf, &outlen, ccm_pt, sizeof(ccm_pt)); /* Output encrypted block */ printf("Ciphertext:\n"); BIO_dump_fp(stdout, outbuf, outlen); /* Finalise: note get no output for CCM */ EVP_EncryptFinal_ex(ctx, outbuf, &outlen); /* Get tag */ EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, 16, outbuf); /* Output tag */ printf("Tag:\n"); BIO_dump_fp(stdout, outbuf, 16); EVP_CIPHER_CTX_free(ctx); } void aes_ccm_decrypt(void) { EVP_CIPHER_CTX *ctx; int outlen, tmplen, rv; unsigned char outbuf[1024]; printf("AES CCM Derypt:\n"); printf("Ciphertext:\n"); BIO_dump_fp(stdout, ccm_ct, sizeof(ccm_ct)); ctx = EVP_CIPHER_CTX_new(); /* Select cipher */ EVP_DecryptInit_ex(ctx, EVP_aes_192_ccm(), NULL, NULL, NULL); /* Set nonce length, omit for 96 bits */ EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, sizeof(ccm_nonce), NULL); /* Set expected tag value */ EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, sizeof(ccm_tag), (void *)ccm_tag); /* Specify key and IV */ EVP_DecryptInit_ex(ctx, NULL, NULL, ccm_key, ccm_nonce); /* Set ciphertext length: only needed if we have AAD */ EVP_DecryptUpdate(ctx, NULL, &outlen, NULL, sizeof(ccm_ct)); /* Zero or one call to specify any AAD */ EVP_DecryptUpdate(ctx, NULL, &outlen, ccm_adata, sizeof(ccm_adata)); /* Decrypt plaintext, verify tag: can only be called once */ rv = EVP_DecryptUpdate(ctx, outbuf, &outlen, ccm_ct, sizeof(ccm_ct)); /* Output decrypted block: if tag verify failed we get nothing */ if (rv > 0) { printf("Plaintext:\n"); BIO_dump_fp(stdout, outbuf, outlen); } else printf("Plaintext not available: tag verify failed.\n"); EVP_CIPHER_CTX_free(ctx); } int main(int argc, char **argv) { aes_ccm_encrypt(); aes_ccm_decrypt(); }
三、解密 dex 文件的 Java 代码
该类仅作为调用 Jni 中的 OpenSSL 解密函数的桥梁 ;
package kim.hsl.multipledex; import java.io.File; import java.io.RandomAccessFile; public class OpenSSL { static { System.loadLibrary("openssl"); } /** * 从文件中读取 Byte 数组 * @param file * @return * @throws Exception */ public static byte[] getBytes(File file) throws Exception { RandomAccessFile r = new RandomAccessFile(file, "r"); byte[] buffer = new byte[(int) r.length()]; r.readFully(buffer); r.close(); return buffer; } /** * 调用 OpenSSL 解密 dex 文件 * @param data * @param path */ public static native void decrypt(byte[] data, String path); }
四、解密 dex 文件的 Jni 代码
解密 dex 文件的方法 , 调用 OpenSSL 开源库中的 api ;
#include <jni.h> #include <stdio.h> #include <android/log.h> #include <malloc.h> #include <string.h> #include <openssl/evp.h> #include "logging_macros.h" //密钥 static uint8_t *userkey = "abcdefghijklmnop"; JNIEXPORT void JNICALL Java_kim_hsl_multipledex_OpenSSL_decrypt(JNIEnv *env, jclass clazz, jbyteArray data, jstring path) { // 将 Java Byte 数组转为 C 数组 jbyte *src = (*env)->GetByteArrayElements(env, data, NULL); // 将 Java String 字符串转为 C char* 字符串 const char *filePath = (*env)->GetStringUTFChars(env, path, 0); // 获取 Java Byte 数组长度 int srcLen = (*env)->GetArrayLength(env, data); /* * 下面的代码是从 OpenSSL 源码跟目录下 demos/evp/aesccm.c 中拷贝并修改 */ // 加密解密的上下文 EVP_CIPHER_CTX *ctx; int outlen, tmplen; unsigned char outbuf[1024]; // 创建加密解密上下文 ctx = EVP_CIPHER_CTX_new(); /* Select cipher 配置上下文解码参数 * 配置加密模式 : * Java 中的加密算法类型 "AES/ECB/PKCS5Padding" , 使用 ecb 模式 * EVP_aes_192_ecb() 配置 ecb 模式 * AES 有五种加密模式 : CBC、ECB、CTR、OCF、CFB * 配置密钥 : * Java 中定义的密钥是 "kimhslmultiplede" */ EVP_DecryptInit_ex(ctx, EVP_aes_192_ecb(), NULL, "kimhslmultiplede", NULL); // 申请解密输出数据内存, 申请内存长度与密文长度一样即可 // AES 加密密文比明文要长 uint8_t *out = malloc(srcLen); // 将申请的内存设置为 0 memset(out, 0, srcLen); // 记录解密总长度 int totalLen = 0; /* * 解密操作 * int EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl, const unsigned char *in, int inl); * 解密 inl 长度的 in , 解密为 outl 长度的 out * 解密的输入数据是 src, 长度为 srcLen 字节, 注意该长度是 int 类型 * 解密的输出数据是 out, 长度为 srcLen 字节, 注意该长度是 int* 指针类型 */ EVP_DecryptUpdate(ctx, out, &outlen, src, srcLen); totalLen += outlen; //更新总长度 /* * int EVP_DecryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl); * 解密时, 每次解密 16 字节, 如果超过了 16 字节 , 就会剩余一部分无法解密, * 之前的 out 指针已经解密了 outlen 长度, 此时接着后续解密, 指针需要进行改变 out + outlen * 此时需要调用该函数 , 解密剩余内容 */ EVP_DecryptFinal_ex(ctx, out + outlen, &outlen); totalLen += outlen; //更新总长度, 此时 totalLen 就是总长度 // 解密完成, 释放上下文对象 EVP_CIPHER_CTX_free(ctx); // 将解密出的明文, 写出到给定的 Java 文件中 FILE *file = fopen(path, "wb"); // 写出 out 指针指向的数据 , 写出个数 totalLen * 1 , 写出到 file 文件中 fwrite(out, totalLen, 1, file); // 关闭文件 fclose(file); // 释放解密出的密文内存 free(out); // 释放 Java 引用 (*env)->ReleaseByteArrayElements(env, data, src, 0); (*env)->ReleaseStringUTFChars(env, path, path); }
