A7 Engineering EmbeddedBlue 505, Руководство пользователя

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Bluetooth Overview
of the security model and they are exposed by the EmbeddedBlue device through the
set
visible
and
set connectable
commands. This is a very coarse level of control, but it is also
quite effective and can be used in combination with other security features.
The second and most complex element of Bluetooth security is access control. This type of
security is only relevant when the module is
connectable
and is designed to provide
protection in this case. The general idea is that remote devices must become trusted before
they will be allowed to connect and communicate with the EmbeddedBlue module. In order to
become trusted, a remote device must present a passkey that matches the stored local
passkey. This only needs to be done once, as both devices will remember their trusted status
and allow future connections with that specific device without exchanging passkeys again.
The EmbeddedBlue module uses the
set security
command to configure access control.
There are three possible settings for security,
off
,
open
, and
closed
. When security is turned
off
, connection attempts will be allowed from all remote devices. When security is set to
open,
connections are only allowed from trusted devices, but new devices can become trusted by
presenting the correct passkey. Forming a trusted relationship is carried out automatically in
this mode the first time that a remote device connects with the EmbeddedBlue module. When
security is set to
closed
, only connections from trusted devices will be allowed and no new
devices may become trusted. Closed security is the most restrictive setting and therefore the
most secure.
The last element of Bluetooth security is confidentiality. Once a link with a trusted device has
been established, it may be important to know that the data being transmitted cannot be
intercepted by a third party. All transmitted data can be encrypted by configuring the
encrypt
setting to
on
. This only has an effect when security is set to either
open
or
closed
. The
EmbeddedBlue module supports 56-bit encryption by default, but 128-bit encryption is
available. Due to export restrictions to certain countries, firmware supporting 128-bit
encryption is only available with proper approval from A7 Engineering.
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