EnOcean PTM 535BZ, Руководство пользователя

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USER MANUAL PREVIEW
PTM 535BZ – BLUETOOTH AND ZIGBEE GREEN POWER PUSHBUTTON TRANSMITTER
© 2021 EnOcean | www.enocean.com F-710-017, V1.0 PTM 535BZ User Manual | v1.0 | May 2021 | Page 19/112
3.3.5.2 Resolvable private address
For some security-critical applications it might be desirable to prevent unauthorized tracking
of PTM 535BZ devices based on the source address used for their radio transmissions. At the
same time, PTM 535BZ devices must be unambiguously identifiable by the receiver. To ad-
dress these requirements, PTM 535BZ can be configured via NFC to use resolvable private
addresses (RPA) as defined by the BLE specification
[2] .
Using resolvable private addresses requires that PTM 535BZ and the receiver both know a
common security key
– the so-called Identity Resolution Key (IRK). This IRK is used to derive
an authentication signature (hash) from a random, plaintext value (prand) as shown in Figure
10 .
Figure 10
– Resolvable private address generation
The mechanism used to generate hash from prand and IRK is shown in Figure 11 .
Figure 11 – Execution flow for resolving private addresses (RPA resolution)
The concatenation of 24 bit prand and 24 bit hash will then form the 48 bit resolvable private
address. Resolvable private addresses are identified by the two most significant bits of prand
being set to
0b01
as shown in Figure 12 .
Figure 12 – BLE resolvable private address structure
0000000...0000000
prand
104 Bit Padding (all zero) 24 Bit prand
Identity Resolution Key (IRK)
128 Bit Identity Resolution Key (IRK)
AES128 Don t Care
hash
104 Bit Don t Care 24 Bit hash