HDCP Interface Independent Adaptation Specification July 18, 2011
Revision 2.1 Digital Content Protection LLC
Page 14 of 72
scheme must be used as defined by PKCS #1 V2.1: RSA
Cryptography Standard. SHA-256 is the underlying hash function.
The mask generation function used is MGF1 which uses SHA-256 as
its underlying hash function.
Verifies integrity of the System Renewability Message (SRM). It does
this by checking the signature of the SRM using kpub
dcp
. Failure of
this integrity check constitutes an authentication failure and causes the
HDCP Transmitter to abort authentication protocol.
The top-level HDCP Transmitter checks to see if the Receiver ID of
the connected device is found in the revocation list. If the Receiver ID
of the connected HDCP Device is found in the revocation list,
authentication fails and the authentication protocol is aborted. SRM
integrity check and revocation check are performed only by the top-
level HDCP Transmitter.
Receives AKE_Send_rrx message from the receiver containing the
64-bit pseudo-random value (r
rx
).
Performs key derivation as explained in Section 2.7 to generate 256-
bit k
d
. k
d
= dkey
0
|| dkey
1
, where dkey
0
and dkey
1
are derived keys
generated when ctr = 0 and ctr = 1 respectively. dkey
0
and dkey
1
are in
big-endian order.
Computes 256-bit H = HMAC-SHA256(r
tx
XOR REPEATER, k
d
)
where HMAC-SHA256 is computed over r
tx
XOR REPEATER and
the key used for HMAC is k
d
. REPEATER is XORed with the least
significant byte of r
tx
.
Receives AKE_Send_H_prime message from the receiver containing
the 256-bit H’. This message must be received within one second after
sending E
kpub
(km) (AKE_No_Stored_km) to the receiver.
Authentication fails and the authentication protocol is aborted if the
message is not received within one second or there is a mismatch
between H and H’.
o If the HDCP Transmitter has a 128-bit Master Key k
m
stored corresponding to
the Receiver ID (See Section 2.2.1)
Sends AKE_Stored_km message to the receiver with the 128-bit
E
kh
(k
m
) and the 128-bit m corresponding to the Receiver ID of the
HDCP Receiver
Verifies integrity of the System Renewability Message (SRM). It does
this by checking the signature of the SRM using kpub
dcp
. Failure of
this integrity check constitutes an authentication failure and causes the
HDCP Transmitter to abort the authentication protocol.
The top-level HDCP Transmitter checks to see if the Receiver ID of
the connected device is found in the revocation list. If the Receiver ID
of the connected HDCP Device is found in the revocation list,
authentication fails and the authentication protocol is aborted.