Libelium Waspmote, Техническое руководство

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Encryption Libraries
22. Encryption Libraries
The Encryption Libraries are designed to add to the Waspmote sensor platform the capabilities necessary to protect the
information gathered by the sensors. To do so two cryptography layers are defined:
• Link Layer: In the first one all the nodes of the network share a common preshared key which is used to encrypt the in-
formation using AES 128. This process is carried out by specific hardware integrated in the same 802.15.4/ZigBee radio,
allowing the maximum efficiency of the sensor nodes energy consumption. This first security layer ensures no third party
devices will be able to even connect to the network (access control).
• Secure Web Server Connection: The second security technique is carried out in Meshlium -the Gateway- where HTTPS
and SSH connections are used to send the information to the Cloud server located on the Internet.
A third optional encryption layer allows each node to encrypt the information using the Public key of the Cloud server. Thus,
the information will be kept confidentially all the way from the sensor device to the web or data base server on the Internet.
22.1. Transmission of sensor data
Information is encrypted in the application layer via software with
AES 256
using the key shared exclusively between the origin
and the destination. Then the packet is encrypted again in the link layer via hardware with
AES 128
so that only trusted packets
be forwarded, ensuring access control and improving the usage of resources of the network.
Figure: Communication diagram