Android逆向初探之心电图

写在前面：
这次逆向实战其实是15年进入公司后不久，某个项目需求得来的操作，当时在Github文章写了一半没写完，今天补充完毕，重新发出来算是给大家一个学习逆向基础的参考_。

前言

“你学习一门技术的最佳时机是三年前，其次是现在。”

背景/目的

项目需求，需要根据手机端接收到的某心电宝测量的心电数据绘制相应的心电图，无奈数据是接收了，
却不知道如何对数据进行相应的处理，瞎搞一通还是绘制不出来，只能傻脸了~

我们的参照App是某德康App，使用的是同一款心电宝，却发现人家竟然能绘制！，舞草，好专业！！

既然正面得不到绘制原理对应的代码，那我就只好逆向xxoo你了，顺带践行心生已久的跨入移动安全这一深坑的想法。

嗯，所以这篇文章的目的呢，也就是实战总结，回顾，加深理解，基本掌握由smali代码逆向出Java代码。

知识点准备

理解本篇内容，需要你通读并理解《Android软件安全与逆向分析》一书的第一章、第二章、第三章、以及第五章5.6小节之前的全部内容。

以下，为该书2013年2月份第一次印刷第一版电子版的研读过程中我自己的书签笔记，希望有助于你的理解，当然，有错请指正。

P32，最后一段中，“第二条指令iload_2取第二个参数”，应该为，“第二条指令iload_2取第三个参数”，
依据之前从“第二部分为下划线右边的数字，表示要操作具体哪个局部变量，索引值从0开始计数...”开始的指令含义介绍；

P33，第一段接上一页的最后一句，“压入第一个参数与第二个参数”，应该为，“压入第二个参数与第三个参数”；

P45，“注意”上面的一段中，倒数第二行，“AAAA/BBBB/CCCC/DDDD/EEEE/FFFF/GGGG/HHHH代表一个8位的数值”，
应该为，“AAAA/BBBB/CCCC/DDDD/EEEE/FFFF/GGGG/HHHH代表一个16位的数值”

P46，3.3.3小节第十二行，“源寄存器为8位，目的寄存器为16位。”，应该为，“目的寄存器为8位，源寄存器为16位。”

P46，3.3.5小节第二行，“‘const/4 vA,#+B’将数值符号扩展为32位后赋给寄存器vA。”，对于“#+B”,
个人理解为在全书中的含义应该都是表示一个常量，每一个大写的字母表示4个位数。
至于“将数值符号扩展为32位后”，我还是有点不太理解~

P53，第一段代码中，本人在实际操作过程中发现，".parameter"指令在JDK1.8且smali.jar版本为2.1.0的环境下不被识别，去掉就能正确编译=_=||

P54，3.4.2小节那一条命令中，“classes.dex”，应该为，“HelloWorld.dex”;
3.4.3小节那两条命令中的“HelloWorld.zip”，应该为，“HelloWorld.dex”；

第五章中提到的诸如sparse-switch-payload字段的格式定义内容都可以暂时略过不看，以后回过头来再研究吧。

逆smali得Java

samli目标文件核心函数代码

   .method protected onDraw(Landroid/graphics/Canvas;)V
   .locals 27
   .param p1, "canvas"    # Landroid/graphics/Canvas;
   .prologue
   .line 50
   invoke-super/range {p0 .. p1}, Landroid/view/View;->onDraw(Landroid/graphics/Canvas;)V
   .line 51
   const/4 v2, -0x1

   move-object/from16 v0, p1

   invoke-virtual {v0, v2}, Landroid/graphics/Canvas;->drawColor(I)V

   .line 53
   new-instance v7, Landroid/graphics/Paint;

   invoke-direct {v7}, Landroid/graphics/Paint;-><init>()V

   .line 54
   .local v7, "paint":Landroid/graphics/Paint;
   const/4 v2, 0x1

   invoke-virtual {v7, v2}, Landroid/graphics/Paint;->setAntiAlias(Z)V

   .line 55
   sget-object v2, Landroid/graphics/Paint$Style;->FILL:Landroid/graphics/Paint$Style;

   invoke-virtual {v7, v2}, Landroid/graphics/Paint;->setStyle(Landroid/graphics/Paint$Style;)V

   .line 58
   const/4 v9, 0x0

   .line 59
   .local v9, "actulWidth":I
   const/4 v8, 0x0

   .line 60
   .local v8, "actulHeight":I
   const/16 v20, 0x0

   .line 61
   .local v20, "perUnitNum":I
   const/16 v19, 0x0

   .line 63
   .local v19, "perMiniNum":I
   move-object/from16 v0, p0

   iget v2, v0, Lcom/mprc/bdk/ecgMeasurement/bluz/DrawHeart;->screenHeight:I

   move-object/from16 v0, p0

   iget v0, v0, Lcom/mprc/bdk/ecgMeasurement/bluz/DrawHeart;->screenWidth:I

   move/from16 v25, v0

   move/from16 v0, v25

   if-le v2, v0, :cond_0

   .line 67
   const/16 v15, 0xa

   .local v15, "i":I
   :goto_0
   const/16 v2, 0x64

   if-lt v15, v2, :cond_1

   .line 87
   :goto_1
   mul-int/lit8 v2, v20, 0x21

   add-int/lit8 v9, v2, 0x4

   .line 90
   mul-int/lit8 v2, v20, 0x26

   add-int/lit8 v8, v2, 0x4

   .line 94
   .end local v15    # "i":I
   :cond_0
   const/16 v2, 0xff

   const/16 v25, 0xb4

   const/16 v26, 0xb4

   move/from16 v0, v25

   move/from16 v1, v26

   invoke-static {v2, v0, v1}, Landroid/graphics/Color;->rgb(III)I

   move-result v2

   invoke-virtual {v7, v2}, Landroid/graphics/Paint;->setColor(I)V

   .line 95
   add-int/lit8 v16, v19, 0x4

   .local v16, "j":I
   :goto_2
   move/from16 v0, v16

   if-lt v0, v9, :cond_4

   .line 102
   add-int/lit8 v15, v19, 0x4

   .restart local v15    # "i":I
   :goto_3
   if-lt v15, v8, :cond_6

   .line 110
   const/high16 v2, -0x10000

   invoke-virtual {v7, v2}, Landroid/graphics/Paint;->setColor(I)V

   .line 111
   const/16 v16, 0x4

   :goto_4
   move/from16 v0, v16

   if-le v0, v9, :cond_8

   .line 115
   const/4 v15, 0x4

   :goto_5
   if-le v15, v8, :cond_9

   .line 120
   move-object/from16 v0, p0

   iget-object v2, v0, Lcom/mprc/bdk/ecgMeasurement/bluz/DrawHeart;->list:Ljava/util/List;

   invoke-interface {v2}, Ljava/util/List;->size()I

   move-result v17

   .line 121
   .local v17, "length":I
   div-int/lit8 v12, v17, 0x4

   .line 122
   .local v12, "firstlength":I
   move v13, v12

   .line 123
   .local v13, "firstpioint":I
   mul-int/lit8 v21, v12, 0x2

   .line 124
   .local v21, "secondpiont":I
   mul-int/lit8 v22, v12, 0x3

   .line 125
   .local v22, "thirdpoint":I
   const/high16 v2, 0x42180000    # 38.0f

   move/from16 v0, v20

   int-to-float v0, v0

   move/from16 v25, v0

   mul-float v2, v2, v25

   int-to-float v0, v12

   move/from16 v25, v0

   div-float v23, v2, v25

   .line 128
   .local v23, "unitlength":F
   const/high16 v2, -0x1000000

   invoke-virtual {v7, v2}, Landroid/graphics/Paint;->setColor(I)V

   .line 129
   const/16 v16, 0x0

   :goto_6
   move/from16 v0, v16

   if-lt v0, v13, :cond_a

   .line 146
   move/from16 v16, v13

   :goto_7
   move/from16 v0, v16

   move/from16 v1, v21

   if-lt v0, v1, :cond_b

   .line 163
   move/from16 v16, v21

   :goto_8
   move/from16 v0, v16

   move/from16 v1, v22

   if-lt v0, v1, :cond_c

   .line 180
   move/from16 v16, v22

   :goto_9
   add-int/lit8 v2, v17, -0x1

   move/from16 v0, v16

   if-lt v0, v2, :cond_d

   .line 195
   return-void

   .line 69
   .end local v12    # "firstlength":I
   .end local v13    # "firstpioint":I
   .end local v16    # "j":I
   .end local v17    # "length":I
   .end local v21    # "secondpiont":I
   .end local v22    # "thirdpoint":I
   .end local v23    # "unitlength":F
   :cond_1
   mul-int/lit8 v2, v15, 0x26

   add-int/lit8 v14, v2, 0x4

   .line 70
   .local v14, "height":I
   mul-int/lit8 v2, v15, 0x1c

   add-int/lit8 v24, v2, 0x4

   .line 71
   .local v24, "width":I
   move-object/from16 v0, p0

   iget v2, v0, Lcom/mprc/bdk/ecgMeasurement/bluz/DrawHeart;->screenHeight:I

   if-gt v14, v2, :cond_2

   .line 73
   add-int/lit8 v15, v15, 0x1

   .line 74
   goto/16 :goto_0

   .line 77
   :cond_2
   rem-int/lit8 v18, v15, 0x5

   .line 78
   .local v18, "mode":I
   if-nez v18, :cond_3

   .line 79
   add-int/lit8 v2, v15, -0x1

   add-int/lit8 v25, v15, -0x1

   rem-int/lit8 v25, v25, 0x5

   sub-int v20, v2, v25

   .line 80
   div-int/lit8 v19, v20, 0x5

   .line 81
   goto/16 :goto_1

   .line 84
   :cond_3
   add-int/lit8 v15, v15, 0x1

   goto/16 :goto_0

   .line 98
   .end local v14    # "height":I
   .end local v15    # "i":I
   .end local v18    # "mode":I
   .end local v24    # "width":I
   .restart local v16    # "j":I
   :cond_4
   add-int/lit8 v2, v16, -0x4

   sub-int v2, v2, v19

   div-int v2, v2, v19

   add-int/lit8 v2, v2, 0x1

   rem-int/lit8 v18, v2, 0x5

   .line 99
   .restart local v18    # "mode":I
   if-eqz v18, :cond_5

   .line 100
   move/from16 v0, v16

   int-to-float v3, v0

   const/high16 v4, 0x40800000    # 4.0f

   move/from16 v0, v16

   int-to-float v5, v0

   int-to-float v6, v8

   move-object/from16 v2, p1

   invoke-virtual/range {v2 .. v7}, Landroid/graphics/Canvas;->drawLine(FFFFLandroid/graphics/Paint;)V

   .line 95
   :cond_5
   add-int v16, v16, v19

   goto/16 :goto_2

   .line 104
   .end local v18    # "mode":I
   .restart local v15    # "i":I
   :cond_6
   add-int/lit8 v2, v15, -0x4

   sub-int v2, v2, v19

   div-int v2, v2, v19

   add-int/lit8 v2, v2, 0x1

   rem-int/lit8 v18, v2, 0x5

   .line 105
   .restart local v18    # "mode":I
   if-eqz v18, :cond_7

   .line 106
   const/high16 v3, 0x40800000    # 4.0f

   int-to-float v4, v15

   int-to-float v5, v9

   int-to-float v6, v15

   move-object/from16 v2, p1

   invoke-virtual/range {v2 .. v7}, Landroid/graphics/Canvas;->drawLine(FFFFLandroid/graphics/Paint;)V

   .line 102
   :cond_7
   add-int v15, v15, v19

   goto/16 :goto_3

   .line 113
   .end local v18    # "mode":I
   :cond_8
   move/from16 v0, v16

   int-to-float v3, v0

   const/high16 v4, 0x40800000    # 4.0f

   move/from16 v0, v16

   int-to-float v5, v0

   int-to-float v6, v8

   move-object/from16 v2, p1

   invoke-virtual/range {v2 .. v7}, Landroid/graphics/Canvas;->drawLine(FFFFLandroid/graphics/Paint;)V

   .line 111
   add-int v16, v16, v20

   goto/16 :goto_4

   .line 117
   :cond_9
   const/high16 v3, 0x40800000    # 4.0f

   int-to-float v4, v15

   int-to-float v5, v9

   int-to-float v6, v15

   move-object/from16 v2, p1

   invoke-virtual/range {v2 .. v7}, Landroid/graphics/Canvas;->drawLine(FFFFLandroid/graphics/Paint;)V

   .line 115
   add-int v15, v15, v20

   goto/16 :goto_5

   .line 132
   .restart local v12    # "firstlength":I
   .restart local v13    # "firstpioint":I
   .restart local v17    # "length":I
   .restart local v21    # "secondpiont":I
   .restart local v22    # "thirdpoint":I
   .restart local v23    # "unitlength":F
   :cond_a
   int-to-float v2, v8

   move/from16 v0, v16

   int-to-float v0, v0

   move/from16 v25, v0

   mul-float v25, v25, v23

   sub-float v4, v2, v25

   .line 133
   .local v4, "pointy":F
   move-object/from16 v0, p0

   iget-object v2, v0, Lcom/mprc/bdk/ecgMeasurement/bluz/DrawHeart;->list:Ljava/util/List;

   move/from16 v0, v16

   invoke-interface {v2, v0}, Ljava/util/List;->get(I)Ljava/lang/Object;

   move-result-object v2

   check-cast v2, Ljava/lang/Integer;

   invoke-virtual {v2}, Ljava/lang/Integer;->intValue()I

   move-result v2

   invoke-static {v2}, Ljava/lang/Integer;->valueOf(I)Ljava/lang/Integer;

   move-result-object v2

   invoke-virtual {v2}, Ljava/lang/Integer;->intValue()I

   move-result v2

   int-to-float v10, v2

   .line 134
   .local v10, "datamv":F
   mul-int/lit8 v2, v20, 0x9

   add-int/lit8 v2, v2, 0x4

   int-to-float v2, v2

   move/from16 v0, v19

   int-to-float v0, v0

   move/from16 v25, v0

   mul-float v25, v25, v10

   const/high16 v26, 0x40880000    # 4.25f

   div-float v25, v25, v26

   sub-float v3, v2, v25

   .line 137
   .local v3, "pointx":F
   int-to-float v2, v8

   add-int/lit8 v25, v16, 0x1

   move/from16 v0, v25

   int-to-float v0, v0

   move/from16 v25, v0

   mul-float v25, v25, v23

   sub-float v6, v2, v25

   .line 138
   .local v6, "pointy2":F
   move-object/from16 v0, p0

   iget-object v2, v0, Lcom/mprc/bdk/ecgMeasurement/bluz/DrawHeart;->list:Ljava/util/List;

   add-int/lit8 v25, v16, 0x1

   move/from16 v0, v25

   invoke-interface {v2, v0}, Ljava/util/List;->get(I)Ljava/lang/Object;

   move-result-object v2

   check-cast v2, Ljava/lang/Integer;

   invoke-virtual {v2}, Ljava/lang/Integer;->intValue()I

   move-result v2

   invoke-static {v2}, Ljava/lang/Integer;->valueOf(I)Ljava/lang/Integer;

   move-result-object v2

   invoke-virtual {v2}, Ljava/lang/Integer;->intValue()I

   move-result v2

   int-to-float v11, v2

   .line 139
   .local v11, "datamv2":F
   mul-int/lit8 v2, v20, 0x9

   add-int/lit8 v2, v2, 0x4

   int-to-float v2, v2

   move/from16 v0, v19

   int-to-float v0, v0

   move/from16 v25, v0

   mul-float v25, v25, v11

   const/high16 v26, 0x40880000    # 4.25f

   div-float v25, v25, v26

   sub-float v5, v2, v25

   .local v5, "pointx2":F
   move-object/from16 v2, p1

   .line 142
   invoke-virtual/range {v2 .. v7}, Landroid/graphics/Canvas;->drawLine(FFFFLandroid/graphics/Paint;)V

   .line 129
   add-int/lit8 v16, v16, 0x1

   goto/16 :goto_6

   .line 149
   .end local v3    # "pointx":F
   .end local v4    # "pointy":F
   .end local v5    # "pointx2":F
   .end local v6    # "pointy2":F
   .end local v10    # "datamv":F
   .end local v11    # "datamv2":F
   :cond_b
   int-to-float v2, v8

   sub-int v25, v16, v13

   move/from16 v0, v25

   int-to-float v0, v0

   move/from16 v25, v0

   mul-float v25, v25, v23

   sub-float v4, v2, v25

   .line 150
   .restart local v4    # "pointy":F
   move-object/from16 v0, p0

   iget-object v2, v0, Lcom/mprc/bdk/ecgMeasurement/bluz/DrawHeart;->list:Ljava/util/List;

   move/from16 v0, v16

   invoke-interface {v2, v0}, Ljava/util/List;->get(I)Ljava/lang/Object;

   move-result-object v2

   check-cast v2, Ljava/lang/Integer;

   invoke-virtual {v2}, Ljava/lang/Integer;->intValue()I

   move-result v2

   invoke-static {v2}, Ljava/lang/Integer;->valueOf(I)Ljava/lang/Integer;

   move-result-object v2

   invoke-virtual {v2}, Ljava/lang/Integer;->intValue()I

   move-result v2

   int-to-float v10, v2

   .line 151
   .restart local v10    # "datamv":F
   mul-int/lit8 v2, v20, 0xf

   add-int/lit8 v2, v2, 0x4

   int-to-float v2, v2

   move/from16 v0, v19

   int-to-float v0, v0

   move/from16 v25, v0

   mul-float v25, v25, v10

   const/high16 v26, 0x40880000    # 4.25f

   div-float v25, v25, v26

   sub-float v3, v2, v25

   .line 154
   .restart local v3    # "pointx":F
   int-to-float v2, v8

   sub-int v25, v16, v13

   add-int/lit8 v25, v25, 0x1

   move/from16 v0, v25

   int-to-float v0, v0

   move/from16 v25, v0

   mul-float v25, v25, v23

   sub-float v6, v2, v25

   .line 155
   .restart local v6    # "pointy2":F
   move-object/from16 v0, p0

   iget-object v2, v0, Lcom/mprc/bdk/ecgMeasurement/bluz/DrawHeart;->list:Ljava/util/List;

   add-int/lit8 v25, v16, 0x1

   move/from16 v0, v25

   invoke-interface {v2, v0}, Ljava/util/List;->get(I)Ljava/lang/Object;

   move-result-object v2

   check-cast v2, Ljava/lang/Integer;

   invoke-virtual {v2}, Ljava/lang/Integer;->intValue()I

   move-result v2

   invoke-static {v2}, Ljava/lang/Integer;->valueOf(I)Ljava/lang/Integer;

   move-result-object v2

   invoke-virtual {v2}, Ljava/lang/Integer;->intValue()I

   move-result v2

   int-to-float v11, v2

   .line 156
   .restart local v11    # "datamv2":F
   mul-int/lit8 v2, v20, 0xf

   add-int/lit8 v2, v2, 0x4

   int-to-float v2, v2

   move/from16 v0, v19

   int-to-float v0, v0

   move/from16 v25, v0

   mul-float v25, v25, v11

   const/high16 v26, 0x40880000    # 4.25f

   div-float v25, v25, v26

   sub-float v5, v2, v25

   .restart local v5    # "pointx2":F
   move-object/from16 v2, p1

   .line 159
   invoke-virtual/range {v2 .. v7}, Landroid/graphics/Canvas;->drawLine(FFFFLandroid/graphics/Paint;)V

   .line 146
   add-int/lit8 v16, v16, 0x1

   goto/16 :goto_7

   .line 166
   .end local v3    # "pointx":F
   .end local v4    # "pointy":F
   .end local v5    # "pointx2":F
   .end local v6    # "pointy2":F
   .end local v10    # "datamv":F
   .end local v11    # "datamv2":F
   :cond_c
   int-to-float v2, v8

   sub-int v25, v16, v21

   move/from16 v0, v25

   int-to-float v0, v0

   move/from16 v25, v0

   mul-float v25, v25, v23

   sub-float v4, v2, v25

   .line 167
   .restart local v4    # "pointy":F
   move-object/from16 v0, p0

   iget-object v2, v0, Lcom/mprc/bdk/ecgMeasurement/bluz/DrawHeart;->list:Ljava/util/List;

   move/from16 v0, v16

   invoke-interface {v2, v0}, Ljava/util/List;->get(I)Ljava/lang/Object;

   move-result-object v2

   check-cast v2, Ljava/lang/Integer;

   invoke-virtual {v2}, Ljava/lang/Integer;->intValue()I

   move-result v2

   invoke-static {v2}, Ljava/lang/Integer;->valueOf(I)Ljava/lang/Integer;

   move-result-object v2

   invoke-virtual {v2}, Ljava/lang/Integer;->intValue()I

   move-result v2

   int-to-float v10, v2

   .line 168
   .restart local v10    # "datamv":F
   mul-int/lit8 v2, v20, 0x15

   add-int/lit8 v2, v2, 0x4

   int-to-float v2, v2

   move/from16 v0, v19

   int-to-float v0, v0

   move/from16 v25, v0

   mul-float v25, v25, v10

   const/high16 v26, 0x40880000    # 4.25f

   div-float v25, v25, v26

   sub-float v3, v2, v25

   .line 171
   .restart local v3    # "pointx":F
   int-to-float v2, v8

   sub-int v25, v16, v21

   add-int/lit8 v25, v25, 0x1

   move/from16 v0, v25

   int-to-float v0, v0

   move/from16 v25, v0

   mul-float v25, v25, v23

   sub-float v6, v2, v25

   .line 172
   .restart local v6    # "pointy2":F
   move-object/from16 v0, p0

   iget-object v2, v0, Lcom/mprc/bdk/ecgMeasurement/bluz/DrawHeart;->list:Ljava/util/List;

   add-int/lit8 v25, v16, 0x1

   move/from16 v0, v25

   invoke-interface {v2, v0}, Ljava/util/List;->get(I)Ljava/lang/Object;

   move-result-object v2

   check-cast v2, Ljava/lang/Integer;

   invoke-virtual {v2}, Ljava/lang/Integer;->intValue()I

   move-result v2

   invoke-static {v2}, Ljava/lang/Integer;->valueOf(I)Ljava/lang/Integer;

   move-result-object v2

   invoke-virtual {v2}, Ljava/lang/Integer;->intValue()I

   move-result v2

   int-to-float v11, v2

   .line 173
   .restart local v11    # "datamv2":F
   mul-int/lit8 v2, v20, 0x15

   add-int/lit8 v2, v2, 0x4

   int-to-float v2, v2

   move/from16 v0, v19

   int-to-float v0, v0

   move/from16 v25, v0

   mul-float v25, v25, v11

   const/high16 v26, 0x40880000    # 4.25f

   div-float v25, v25, v26

   sub-float v5, v2, v25

   .restart local v5    # "pointx2":F
   move-object/from16 v2, p1

   .line 176
   invoke-virtual/range {v2 .. v7}, Landroid/graphics/Canvas;->drawLine(FFFFLandroid/graphics/Paint;)V

   .line 163
   add-int/lit8 v16, v16, 0x1

   goto/16 :goto_8

   .line 183
   .end local v3    # "pointx":F
   .end local v4    # "pointy":F
   .end local v5    # "pointx2":F
   .end local v6    # "pointy2":F
   .end local v10    # "datamv":F
   .end local v11    # "datamv2":F
   :cond_d
   int-to-float v2, v8

   sub-int v25, v16, v22

   move/from16 v0, v25

   int-to-float v0, v0

   move/from16 v25, v0

   mul-float v25, v25, v23

   sub-float v4, v2, v25

   .line 184
   .restart local v4    # "pointy":F
   move-object/from16 v0, p0

   iget-object v2, v0, Lcom/mprc/bdk/ecgMeasurement/bluz/DrawHeart;->list:Ljava/util/List;

   move/from16 v0, v16

   invoke-interface {v2, v0}, Ljava/util/List;->get(I)Ljava/lang/Object;

   move-result-object v2

   check-cast v2, Ljava/lang/Integer;

   invoke-virtual {v2}, Ljava/lang/Integer;->intValue()I

   move-result v2

   invoke-static {v2}, Ljava/lang/Integer;->valueOf(I)Ljava/lang/Integer;

   move-result-object v2

   invoke-virtual {v2}, Ljava/lang/Integer;->intValue()I

   move-result v2

   int-to-float v10, v2

   .line 185
   .restart local v10    # "datamv":F
   mul-int/lit8 v2, v20, 0x1b

   add-int/lit8 v2, v2, 0x4

   int-to-float v2, v2

   move/from16 v0, v19

   int-to-float v0, v0

   move/from16 v25, v0

   mul-float v25, v25, v10

   const/high16 v26, 0x40880000    # 4.25f

   div-float v25, v25, v26

   sub-float v3, v2, v25

   .line 188
   .restart local v3    # "pointx":F
   int-to-float v2, v8

   sub-int v25, v16, v22

   add-int/lit8 v25, v25, 0x1

   move/from16 v0, v25

   int-to-float v0, v0

   move/from16 v25, v0

   mul-float v25, v25, v23

   sub-float v6, v2, v25

   .line 189
   .restart local v6    # "pointy2":F
   move-object/from16 v0, p0

   iget-object v2, v0, Lcom/mprc/bdk/ecgMeasurement/bluz/DrawHeart;->list:Ljava/util/List;

   add-int/lit8 v25, v16, 0x1

   move/from16 v0, v25

   invoke-interface {v2, v0}, Ljava/util/List;->get(I)Ljava/lang/Object;

   move-result-object v2

   check-cast v2, Ljava/lang/Integer;

   invoke-virtual {v2}, Ljava/lang/Integer;->intValue()I

   move-result v2

   invoke-static {v2}, Ljava/lang/Integer;->valueOf(I)Ljava/lang/Integer;

   move-result-object v2

   invoke-virtual {v2}, Ljava/lang/Integer;->intValue()I

   move-result v2

   int-to-float v11, v2

   .line 190
   .restart local v11    # "datamv2":F
   mul-int/lit8 v2, v20, 0x1b

   add-int/lit8 v2, v2, 0x4

   int-to-float v2, v2

   move/from16 v0, v19

   int-to-float v0, v0

   move/from16 v25, v0

   mul-float v25, v25, v11

   const/high16 v26, 0x40880000    # 4.25f

   div-float v25, v25, v26

   sub-float v5, v2, v25

   .restart local v5    # "pointx2":F
   move-object/from16 v2, p1

   .line 193
   invoke-virtual/range {v2 .. v7}, Landroid/graphics/Canvas;->drawLine(FFFFLandroid/graphics/Paint;)V

   .line 180
   add-int/lit8 v16, v16, 0x1

   goto/16 :goto_9        
   .end method

对应的Java代码

@Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawColor(-1);
        Paint paint = new Paint();//.local v7
        paint.setAntiAlias(true);
        paint.setStyle(Paint.Style.FILL);
         int actulWidth = 0;//.locala v9
         int actulHeight = 0;//.locala v8
         //Java中的float是32位的,double是64位的
         int perUnitNum = 0;//.local v20
         int perMiniNum = 0;//.local v19
         //还是有错误
         if(this.screenHeight>this.screenWidth){//否则跳转到cond_0
            int i=0xa;//.local v15
            goto_0:
            for(;i<0x64;i+=0x1){//.line 73 //.line 83 cond_3
                //cond_1
                int height = i*0x26+0x4;//.local v14
                int width = i*0x1c+0x4;//.local v24
                if(height>this.screenHeight){
                    //cond_2
                    int mode = i%0x5;//.line 78 //?貌似作用域不一样
                    if(mode==0){
                        perUnitNum = (i-0x1)-(i-0x1)%0x5;
                        perMiniNum = perUnitNum/0x5;//.line 80
                        //goto/16 :goto_1
                        break;//.line 81
                    }
                }
            }
            actulWidth=perUnitNum*0x21+0x4;//.line 87
            actulHeight=perUnitNum*0x26+0x4;//.line 90
            //.line 94  .end local v15 #"i":I
         }/*else{*/
             //cond_0
             paint.setColor(Color.rgb(0xff, 0xb4, 0xb4));
         /*}*/
         int j = perMiniNum+0x4;//.line 95 .local v16
         goto_2:
         for(;j<actulWidth;j+=perMiniNum){
             //cond_4
             int mode = ((j - 0x4 - perMiniNum) / perMiniNum + 0x1) % 0x5;//.line 99 //.local v18
                if (mode != 0) {
                    canvas.drawLine(j, 4.0f, j, actulHeight, paint);//.line 100
                } 
         }
         
         int i = perMiniNum+0x4;//.line 102
         //.restart local v15
         goto_3:
             for(;i<actulHeight;i+=perMiniNum){
                 //cond_6
                 int mode = ((i - 0x4 - perMiniNum) / perMiniNum + 0x1) % 0x5;//.line 105 //.restart local v18
                if(mode != 0){//否则cond_7
                    canvas.drawLine(4.0f, i, actulWidth, i, paint);//.line 106
                }    
             }
         
         //.line 110
         paint.setColor(-0x10000);
         j=0x4;
         goto_4://.line 111
         for(;j<=actulWidth;j+=perUnitNum){
             //cond_8
             canvas.drawLine(j, 4.0f, j, actulHeight, paint);//.line 114
         }
         
         i=+0x4;//.line 115
         goto_5:
         for(;i<=actulHeight;i+=perUnitNum){
             //.line 117 //:cond_9
             canvas.drawLine(4.0f, i, actulWidth, i, paint);
         }
         
         //.line 120
        int length = this.list.size();//.local v17 //.line 121
        int firstlength = length / 0x4;//.line 122 //.local v12
        int firstpoint = firstlength;//.line 123 //.local v13
        int secondpoint = firstlength * 0x2;//.line 124 //.local v21
        int thirdpoint = firstlength * 0x3;//.line 125 //.local v22
        float unitlength = perUnitNum * 38.0f / (firstlength * 1.0f);//.line 128 //.local v23
        paint.setColor(-0X1000000); 
        j = 0x0;//.line 129
        goto_6:
        for(;j<firstpoint;j+=0x1){
            //cond_a
            float pointy = actulHeight - j * unitlength;// .local v4 //.line 133
            float datamv = (float) Integer.valueOf(((Integer) this.list.get(j)).intValue()).intValue();//.local v10 //.line 134
            float pointx = (perUnitNum * 0x9 + 0x4) - perMiniNum * datamv / 4.25f;//.line 137 //.local v3
            float pointy2 = actulHeight - (j + 0x1) * unitlength;//.line 138 //.local v6
            float datamv2 = Integer.valueOf(((Integer) this.list.get(j + 0x1)).intValue()).intValue();//.local v11 //.line 139
            float pointx2 = (perUnitNum * 0x9 + 0x4) - perMiniNum * datamv2 / 4.25f;//.local v5
            canvas.drawLine(pointx, pointy, pointx2, pointy2, paint);//.line 142 
        }
        
        //.line 146
        j=firstpoint;
        goto_7:
        for(;j<secondpoint;j+=0x1){
            //cond_b
            float pointy = actulHeight - (j - firstpoint) * unitlength;//.line 150 //.restart local v4
            float datamv = (float) Integer.valueOf(((Integer) this.list.get(j)).intValue()).intValue();//.line 151 //.restart local v10
            float pointx = perUnitNum * 0xf + 0x4 - perMiniNum * datamv / 4.25f;//.line 154 //.restart local v3
            float pointy2 = actulHeight - (j - firstpoint + 0x1) * unitlength;//.line 155 //.restart local v6
            float datamv2 = (float) Integer.valueOf((Integer) this.list.get(j + 0x1).intValue()).intValue();//.line 156 //.restart local v11
            float pointx2 = perUnitNum * 0xf + 0x4 - perMiniNum * datamv2 / 4.25f;//.restart local v5
            canvas.drawLine(pointx, pointy, pointx2, pointy2, paint);//.line 159
        }
        
        //.line 163
        j=secondpoint;
        goto_8:
        for(;j<thirdpoint;j+=0x1){
            //cond_c
            float pointy = actulHeight - (j - secondpoint) * unitlength;
            float datamv = Integer.valueOf((Integer) this.list.get(j).intValue()).intValue();
            float pointx = (perUnitNum * 0x15 + 0x4) - perMiniNum * datamv / 4.25f;
            float pointy2 = actulHeight - ((j - secondpoint) + 0x1) * unitlength;
            float datamv2 = Integer.valueOf((Integer) this.list.get(j + 0x1).intValue()).intValue();
            float pointx2 = (perUnitNum * 0x15 + 0x4) - perMiniNum * datamv2 / 4.25f;
            canvas.drawLine(pointx, pointy, pointx2, pointy2, paint);//.line 176
        }
        
        //.line 180
        j=thirdpoint;
        goto_9:
        for(;j<(length-1);j+=0x1){
            //cond_d
            float pointy = actulHeight - (j - thirdpoint) * unitlength;
            float datamv = Integer.valueOf((Integer) this.list.get(j).intValue()).intValue();
            float pointx = perUnitNum * 0x1b + 0x4 - perMiniNum * datamv / 4.25f;
            float pointy2 = actulHeight - (j - thirdpoint + 0x1) * unitlength;
            float datamv2 = Integer.valueOf((Integer) this.list.get(j + 0x1).intValue()).intValue();
            float pointx2 = perUnitNum * 0x1b + 0x4 - perMiniNum * datamv2 / 4.25f;
            canvas.drawLine(pointx, pointy, pointx2, pointy2, paint);//.line 193
        }
    }

Java代码请自行对结构逻辑进行优化吧，也就是去掉goto;标识符的工作=

写在后面：

相关资料工具

在你有可测试数据的基础上，将我们根据语法逆向出来的.smali文件替换掉原APK对应文件的.smali文件并重新编译，根据测试结果对比来检查我们操作结果的正确性，推荐工具APK改之理

当时记录的可用测试数据：
[-127,-90]与[100,128]
这两个区段随机抽取整数64到100个，在你自定义的View上通过如上方法绘制即可看到类似结果,如下图所示：

QQ图片20151118174912.png

自己加了标记的《Android软件安全与逆向分析》一书的PDF文件，仅供学习之用，有资金基础的还是推荐买本实体书，支持下作者：
链接: http://pan.baidu.com/s/1eRCdEs6 密码: wrqg

原APK文件：
链接: http://pan.baidu.com/s/1i5CTJil 密码: vikw

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