简介：我在不完全熟悉蓝牙堆栈和协议的情况下遇到这个问题，因此这可能需要几轮编辑，因为我的假设中的错误被揭示出来。
我正在尝试连接到蓝牙设备Scosche myTREK Pulse Monitor。我能够使用 Android 的“官方”应用程序连接到设备，并使用hcidump. 我可以通过链接密钥交换阅读和理解连接过程；但是，设备随后会发送一个 HCIEncrypt Change事件，之后大多数（但不是全部）数据包都被标记为 ACL 数据包，并且难以解释。
基本问题是：蓝牙是否加密数据，是否有安全解密的方法？这与转向 ACL 数据包有关吗？
这是给定连接提供的数据包输出示例hcidump，从传递链接密钥开始。（>指监视器发送数据）
> HCI Event: Link Key Request (0x17) plen 6
0000: ** ** ** ** ** ** ??????
< HCI Command: Link Key Request Reply (0x01|0x000b) plen 22
0000: ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ???????????????
0010: ** ** ** ** ** ** ??????
> HCI Event: Command Complete (0x0e) plen 10
0000: 01 0b 04 00 ** ** ** ** ** ** ....??????
> HCI Event: Encrypt Change (0x08) plen 4
0000: 00 0c 00 01 ....
> ACL data: handle 12 flags 0x02 dlen 12
L2CAP(s): Connect req: psm 1 scid 0x0040
< ACL data: handle 12 flags 0x00 dlen 16
0000: 0c 00 01 00 03 02 08 00 40 00 40 00 01 00 00 00 ........@.@.....
< ACL data: handle 12 flags 0x00 dlen 10
0000: 06 00 01 00 0a 01 02 00 02 00 ..........
> HCI Event: Number of Completed Packets (0x13) plen 5
0000: 01 0c 00 02 00 .....
> ACL data: handle 12 flags 0x02 dlen 16
L2CAP(s): Info rsp: type 2 result 0
Extended feature mask 0x0000
< ACL data: handle 12 flags 0x00 dlen 16
0000: 0c 00 01 00 03 02 08 00 40 00 40 00 00 00 00 00 ........@.@.....
< ACL data: handle 12 flags 0x00 dlen 12
0000: 08 00 01 00 04 02 04 00 40 00 00 00 ........@...
> HCI Event: Number of Completed Packets (0x13) plen 5
0000: 01 0c 00 02 00 .....
> ACL data: handle 12 flags 0x02 dlen 16
L2CAP(s): Config req: dcid 0x0040 flags 0x00 clen 4
MTU 48
< ACL data: handle 12 flags 0x00 dlen 18
0000: 0e 00 01 00 05 03 0a 00 40 00 00 00 00 00 01 02 ........@.......
0010: 30 00 0.
> ACL data: handle 12 flags 0x02 dlen 14
L2CAP(s): Config rsp: scid 0x0040 flags 0x00 result 0 clen 0
Success
> ACL data: handle 12 flags 0x02 dlen 36
L2CAP(d): cid 0x0040 len 32 [psm 0]
0000: 06 00 01 00 1b 35 11 1c 00 00 00 00 de ca fa de .....5......??·?
0010: de ca de af de ca ca fe 00 26 35 03 09 00 04 00 ???»????.&5.....
< ACL data: handle 12 flags 0x00 dlen 33
0000: 1d 00 40 00 07 00 01 00 18 00 15 35 13 35 11 09 ..@........5.5..
0010: 00 04 35 0c 35 03 19 01 00 35 05 19 00 03 08 12 ..5.5....5......
0020: 00 .
> HCI Event: Number of Completed Packets (0x13) plen 5
0000: 01 0c 00 02 00 .....
> ACL data: handle 12 flags 0x02 dlen 12
L2CAP(s): Disconn req: dcid 0x0040 scid 0x0040
< ACL data: handle 12 flags 0x00 dlen 12
0000: 08 00 01 00 07 04 04 00 40 00 40 00 ........@.@.
> ACL data: handle 12 flags 0x02 dlen 12
L2CAP(s): Connect req: psm 3 scid 0x0041
< ACL data: handle 12 flags 0x00 dlen 16
0000: 0c 00 01 00 03 05 08 00 40 00 41 00 00 00 00 00 ........@.A.....
> HCI Event: Number of Completed Packets (0x13) plen 5
0000: 01 0c 00 02 00 .....
> ACL data: handle 12 flags 0x02 dlen 16
L2CAP(s): Config req: dcid 0x0040 flags 0x00 clen 4
MTU 895
< ACL data: handle 12 flags 0x00 dlen 18
0000: 0e 00 01 00 05 06 0a 00 41 00 00 00 00 00 01 02 ........A.......
0010: 7f 03 ..
< ACL data: handle 12 flags 0x00 dlen 16
0000: 0c 00 01 00 04 03 08 00 41 00 00 00 01 02 f5 03 ........A.....?.
> HCI Event: Number of Completed Packets (0x13) plen 5
0000: 01 0c 00 02 00 .....
> ACL data: handle 12 flags 0x02 dlen 18
L2CAP(s): Config rsp: scid 0x0040 flags 0x00 result 0 clen 4
MTU 1013
在这一点上，设备提供的有效负载在运行之间变化很大，更不用说在一次运行中了。为简洁起见，我已将日志的其余部分放在粘贴箱中：链接