某站平台的签名算法分享

• 先charles抓包，api.xxxxxx.com域名的包

• 分析包 看到路径参数如下

• appkey=1d8b6e7d45233436&build=5531000&channel=dw056&mobi_app=android&mode=0&oid=326052200&plat=2&platform=android&ps=20&statistics=%7B%22appId%22%3A1%2C%22platform%22%3A3%2C%22version%22%3A%225.53.1%22%2C%22abtest%22%3A%22%22%7D&ts=1705305495&type=1&sign=2c9086d4acc853a017ec087699902634
  可以看到一个sign,是个32字符，128位，直觉告诉我可能是个md5签名

• 然后用jadx打开xxx.apk包，全局搜索sign字符串，在众多函数方法中，找到一个SignedQuery函数，跟进去看，发现又个loadLibrary(xxx),那么直接告诉我是在一个so里

• 用apktool把xxx.apk decode出来，拿到libxxx.so

• 用ida打开该libxxx.so,直接看JNI_OnLoad函数，找到这一行

  if ( (*v5)->RegisterNatives(v5, v4, (const JNINativeMethod *)®ister_native_struct, 5) < 0

• register_native_struct跟进去

 

• 每个函数进去看下，有惊喜，确实是个md5算法，找到 md5_impl，跟进去看看算法参数

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168

  int __fastcall md5_impl(JNIEnv *a1, jobject (*a2)(JNIEnv *, jclass, jmethodID, ...)) { JNIEnv *v2; // r11 jobject (*v3)(JNIEnv *, jclass, jmethodID, ...); // r6 const char *v4; // r2 const char *v5; // r1 int result; // r0 int v7; // r0 JNIEnv v8; // r1 int v9; // r0 int v10; // r4 int v11; // r0 int v12; // r10 signed int v13; // r9 int v14; // r5 int v15; // r8 time_t v16; // r0 int v17; // r6 int v18; // r5 const char *input_str; // r8 _DWORD *v20; // r10 int v21; // r4 _DWORD *v22; // r0 int v23; // r1 int v24; // r2 int v25; // r0 unsigned int input_len; // r5 signed int v27; // r4 char *v28; // r5 int v29; // r4 const char *v30; // [sp+8h] [bp-C0h] int v31; // [sp+8h] [bp-C0h] int v32; // [sp+Ch] [bp-BCh] char v33; // [sp+10h] [bp-B8h] int s; // [sp+38h] [bp-90h] int v35; // [sp+3Ch] [bp-8Ch] int v36; // [sp+40h] [bp-88h] int v37; // [sp+44h] [bp-84h] char v38[24]; // [sp+90h] [bp-38h] int v39; // [sp+A8h] [bp-20h] v2 = a1; v3 = a2; if ( !sub_2D20((int)a1) ) goto LABEL_5; v4 = "com.xxxxxxxx.nativelibrary.SignedQuery"; v5 = "java/lang/ClassNotFoundException"; LABEL_3: sub_401C((int)v2, (int)v5, (int)v4); result = 0; while ( _stack_chk_guard != v39 ) { LABEL_5: if ( !v3 ) {   v5 = "java/lang/NullPointerException";   v4 = "Null params!";   goto LABEL_3; } v7 = is_empty(v2, (int)v3); v8 = *v2; if ( v7 ) {   v3 = v8->NewObject;   result = ((int (__fastcall *)(JNIEnv *, int, int, _DWORD, _DWORD))v3)(              v2,              cls_signed_query,              signed_query_init,              0,              0); } else {   v9 = ((int (__fastcall *)(JNIEnv *, const char *))v8->NewStringUTF)(v2, "appkey");   v10 = v9;   v11 = sub_60CC(v2, (int)v3, v9);          // // 校验appkey   v12 = v11;   if ( v11 )   {     v30 = (const char *)((int (__fastcall *)(JNIEnv *, int, _DWORD))(*v2)->GetStringUTFChars)(v2, v11, 0);     v13 = check_app_key_get_type(v30);   }   else   {     v13 = -1;     v30 = 0;   }   v14 = ((int (__fastcall *)(JNIEnv *, const char *))(*v2)->NewStringUTF)(v2, "ts");   v15 = sub_60CC(v2, (int)v3, v14);   if ( !v15 )   {     v36 = 0;     v37 = 0;     s = 0;     v35 = 0;     v16 = time(0);     sprintf((char *)&s, "%ld", v16);     ((void (__fastcall *)(JNIEnv *, int *))(*v2)->NewStringUTF)(v2, &s);     sub_6188((int)v2);   }   sub_41D0(v2, v14);   sub_41D0(v2, v15);   v17 = ((int (__fastcall *)(JNIEnv *, int, int, jobject (*)(JNIEnv *, jclass, jmethodID, ...)))(*v2)->CallStaticObjectMethod)(           v2,           cls_signed_query,           method_signed_query_r,           v3);   v18 = 0;   if ( sub_3F70((int)v2) )     v17 = 0;   v32 = v17;   input_str = (const char *)((int (__fastcall *)(JNIEnv *, int, _DWORD))(*v2)->GetStringUTFChars)(v2, v17, 0);   if ( v13 != -1 )   {     ((void (__fastcall *)(JNIEnv *, int, const char *))(*v2)->ReleaseStringUTFChars)(v2, v12, v30);     v20 = malloc(0x10u);     if ( v20 )     {       v31 = v10;       v21 = global_key[v13];       v22 = &global_key[v13];       v23 = v22[5];       v24 = v22[10];       v25 = v22[15];       *v20 = v21;       v20[1] = v23;       v20[2] = v24;       v20[3] = v25;       _aeabi_memclr8(&v33, 33);       input_len = strlen(input_str);       _aeabi_memclr8(v38, 24);       _aeabi_memclr8(&s, 88);       md5_init(&s);       md5_update((int)&s, (int)input_str, input_len);       sprintf(v38, "%08x", v21);       md5_update((int)&s, (int)v38, 8u);       v27 = 1;       do       {         sprintf(v38, "%08x", v20[v27]);         md5_update((int)&s, (int)v38, 8u);         ++v27;       }       while ( v27 != 4 );       md5_final((int)v38, (int)&s);       v28 = &v33;       v29 = 0;       do       {         sprintf(v28, "%02x", (unsigned __int8)v38[v29++]);         v28 += 2;       }       while ( v29 != 16 );       free(v20);       v10 = v31;       v18 = ((int (__fastcall *)(JNIEnv *, char *))(*v2)->NewStringUTF)(v2, &v33);     }     else     {       v18 = 0;     }   }   sub_41D0(v2, v10);   v3 = (*v2)->NewObject;   result = ((int (__fastcall *)(JNIEnv *, int, int, int, int))v3)(v2, cls_signed_query, signed_query_init, v32, v18); } } return result;}

• 分析代码，发现关键在 check_app_key_get_type和global_key，一个是app key获取type，还有一个存着类似于secret key的 global key

• 整体看下来，结论就是 md5加密，按参数字典序排序，然后拼接SecretKey,再md5得到sign，取其中一个type来验证下：

• 

  
  和app请求生成的sign一样,secret key打码，如果想要，可以按步骤自己去试试，实测成功，关键地方都写清楚了

 最后，写个python脚本试试，确实都能访问，这里脚本就不放了，求赞求加精，求账号升级，感谢