2.2.1.3.3 The Proximity Response Message

The proximity response message contains four sections:

Header: Contains the protocol version supported by the receiver and the message type. The protocol version MUST be 0x03. The message type for proximity response messages is 0x05.

Sequence number: Contains the sequence number. The sequence number MUST be the same one included in the proximity challenge message.

Session ID: Contains the session ID. The receiver MUST send the same 128-bit session ID that was passed to it in the registration response message.

Encrypted challenge value (nonce): Contains the nonce. The nonce is the 128-bit random value in the proximity challenge message, encrypted using the AES content encryption key in ECB mode.


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ProtocolVersion

MessageType

SequenceNumber

SessionID (16 bytes)

...

...

...

EncryptedNonce (16 bytes)

...

...

...

ProtocolVersion (1 byte): Contains the protocol version supported by the receiver. The protocol version MUST be 0x03.

MessageType (1 byte): Contains the message type. The message type for proximity challenge messages is 0x05.

SequenceNumber (1 byte): Contains the sequence number. This 8-bit sequential number MUST be incremented by one every time the proximity challenge message is sent to the transmitter.

SessionID (16 bytes): Contains the session ID. The receiver MUST send the same 128-bit session ID that was passed to it in the registration response message.

EncryptedNonce (16 bytes): Contains the encrypted nonce. This is the 128-bit random value from the proximity challenge message that was encrypted using the content encryption key using AES in ECB mode.