2/24/2008 9T6WP
BCM7405
Preliminary Hardware Data Module
Functional Description
06/29/07
Bro a d c o m C o rp o r a ti o n
Page 1-20
Data Transport Processor
Document
7405-1HDM00-R
Condition Access Descramblers (The Downstream Descramblers)
The data transport module provides a DVB, 1DES, 3DES, AES, and a Multi2 descrambler for Conditional Access for up to
128 PID channels which may include video, audio, and data streams.
The DVB engine supports full and conformance mode. It also supports both transport and PES level descrambling.
The 1DES, 3DES and multi2 supports ECB and CBC mode with selectable residue termination modes of partial block
unscrambled, residual block termination, and cipher-text stealing. CBC mode with cipher-text stealing is not a reversible
mode.
The Multi2 descrambler supports four separate 256-bit system keys, selectable for each PID channel. Thus, it supports up
to four different Multi2 system headends. The descrambler descrambles the packet payload as usual, using termination
modes of cipher text stealing, residual termination, or partial block unscrambled. The Multi2 max round count is 32. Valid
values are 0x20, 0x18, 0x10, and 0x08.
The AES descrambler supports only CBC mode. Keys and modes are configured in a 896x64 key table. Each PID channel
has index entry to point a set of keys and modes to be used for descrambling. Multiple PID channels can point to same or
different key sets.
The descrambler also extracts the 2-bit scrambling control from each transport packet for each PID channel, and save them
in registers for the host CPU to read. The host CPU can always read the latest scrambling control bits for each channel, and
a per PID status bit signals whether the scrambling bit is valid since the last read.
NDS ICAM Module
An NDS ICAM 2.2a module is supported.
Copy Protection
Memory to Memory DMA with Security
For copy protection, we support a memory to memory DMA subsystem that can scramble or descramble data. The Mem-to-
Mem Security module performs the scrambling/descrambling function of that subsystem. The Mem-to-Mem DMA portion of
the subsystem resides outside data transport. This module also supports Transport packet parsing function, so only payload
data is scrambled/descrambled.
The Mem-to-Mem Security module may be programmed to perform the following functions:
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ECB mode scrambling/descrambling with 3DES core in ABA or ABC modes (64 bits data, 128/192 bits key).
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CBC mode scrambling/descrambling with 3DES core in ABA or ABC modes (64 bits data, 128/192 bits key).
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ECB mode scrambling/descrambling with DES core (64 bits data, 64 bits key).
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CBC mode scrambling/descrambling with DES core (64 bits data, 64 bits key).
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ECB mode scrambling/descrambling with AES core (128 bits data, 128/192 bits key).
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Counter mode scrambling/descrambling with AES core (128 bits data, 128 bits key).
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ECB mode scrambling/descrambling with C2 core (64 bits data, K bits key).
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C-CBC mode scrambling/descrambling with C2 core (N x 64 bits data, K bits key).
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Sector mode data descramble with CSS core (2048 x 8 bits data, K bit key).
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CBC mode scrambling/descrambling with AES core as defined by AACS and DTCP (128 bit data, 128 bit key).
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Supports 96 x 64 bit key table. Each key set requires one 64 bit mode word. Cores that use longer key length will use
multiple keys.
•
M6 scrambler/descrambler for DTCP.