User's Manual
USER MANUAL PREVIEW
PTM 535BZ – BLUETOOTH AND ZIGBEE GREEN POWER PUSHBUTTON TRANSMITTER
© 2022 EnOcean | www.enocean.com F-710-017, V1.0 PTM 535BZ User Manual | v1.2 | July 2021 | Page 112/121
D. Authentication of PTM 535BZ BLE data telegrams
PTM 535BZ provides the option to authenticate BLE data telegrams as described in Chapter
3.4.2. The authentication mechanism used by PTM 535BZ is standardized as RFC3610 [1].
The following description aims to summarize the security processing steps for users not
deeply familiar with cryptography in general or RFC3610 in particular.
D.1 Algorithm input parameters
The purpose of the security processing in PTM 535BZ is to calculate a unique signature that
can be used to verify authenticity (telegram has not been modified) and originality (telegram
comes from the assumed sender) of a telegram.
To do so, two types of algorithm parameters are required:
Constant algorithm input parameters
These parameters identify high level algorithm and telegram properties and are the
same for any PTM 535BZ telegram
Variable algorithm input parameters
These parameters identify telegram-specific parameters and therefore depend on the
specifics of the transmitted telegram
D.1.1 Constant input parameters
The RFC3610 implementation in PTM 535BZ requires two constant input parameters:
Length field size
This is the size (in byte) of the field used to encode the length of the input data (which
is the payload to be authenticated).
The size of the authenticated PTM 535BZ payload is 9 byte; therefore one byte would
be easily sufficient to encode the payload size. The minimum value permitted by the
standard is however 2 bytes which is therefore chosen.
Signature size
This is the desired size of the generated signature which is 4 byte for PTM 535BZ
Table 34 below summarizes these constant algorithm parameters.
Parameter Comment / Description Example
Length Field Size
Size (in bytes) of the field used to encode
the input length
2 (always, minimum permissible size)
Signature Size
Desired size (in byte) of the signature
generated by the algorithm
4 (always)
Table 34 – Constant algorithm input parameters