NXP Semiconductors
UM0801-03
PN533 User Manual
Table 6. Sequence of secured DEP started by Initiator
Step Description
1 In case of Secured DEP activated by the Initiator, the I-Host activates this secure channel by
sending its Public key with InDataExchange command (See §8.4.8, p.100). Bits 7:5 of the Tg
field are set to 001.
2 The T-Host is informed that the communication has to be secured, because the returned
status of the GetData response (See §8.4.17, p. 135) is equal to 0x20 (See Table 15, p. 50).
3 The T-Host replies with a SetDataSecure command with contained its Public Key.
4 The I-Host receives the T-Host Public Key within the InDataExchange response. And the
returned status of this command is equal to: 0x20 (if the RF communication was successful).
5 A same exchange is done with SSE_ACK_REQ and SSE_ACK RES to confirm the Public
Keys.
6 Lastly, the exchange of data can be done in secure mode.
Table 7. Sequence of secured DEP started by Target
Step Description
1 In this case, the I-Host starts a basic Data Exchange Protocol, but the T-Host requests for a
secure communication. The T-Host activates this secure channel by sending its Public key
with SetDataSecure command (See §8.4.19, p. 138).
2 The I-Host is informed that the communication has to be secured, because the returned
status of the InDataExchange response (See §8.4.8, p.100) is equal to 0x20 (See Table 15,
p. 50).
3 The I-Host replies with an InDataExchange command with contained its Public Key.
4 The T-Host receives the I-Host Public Key within the TgGetData response. And the returned
status of this command is equal to: 0x20 (if the RF communication was successful).
5 A same exchange is done with SSE_ACK_REQ and SSE_ACK RES to confirm the Public
Keys.
6 Afterwards, the target will send the encrypted data to the Initiator in secure mode.
Remark 1:
If the InDataExchange command is used with the 5
th
bit of Tg field equal to
1, or SetDataSecure command is used, or SetMetaDataSecure command is used,
then the PN533 shall set bits 7:5 of the PFB to 001.
Remark 2:
If bits 7:5 of PFB are set to 001, then the communication is secured and the
returned status of the GetData or InDataExchange response is set to 0x20 (if the RF
communication was successful).
Remark 3:
For enabling the NFC Secure layer, the Host has to set the fSecure bit of the
SetParameters command to 1 (see §8.2.8, p.66).
UM0801-03 © NXP B.V. 2008. All rights reserved.
User Manual Rev. 03 - 14 January 2009 20 of 175