MSC8144E Reference Manual, Rev. 3
26-50
Freescale
Semiconductor
Security Engine (SEC)
be performed using a single descriptor (with the MDEU acting as sole or secondary EU), use the
Mode Register bit settings listed in Table 26-2
To generate an HMAC for a message that is spread across a sequence of descriptors, use the
Mode Register bit settings listed in Table 26-3.
All descriptors other than the final descriptor must output the intermediate message digest for the
next descriptor to reload as MDEU context. SSL-MAC operations cannot be spread across a
sequence of descriptors. Additional information on descriptors can be found in Section 26.2.1.1,
Descriptors, on page 26-9.
26.4.4.2 MDEU Key Size Register
The MDEU key size value indicates the number of bytes of key memory that should be used in
HMAC generation. MDEU supports at most 64 bytes of key. MDEU generates a key size error if
the value written to this register exceeds 64 bytes.
26.4.4.3 MDEU Data Size Register
The MDEU Data Size Register indicates the number of bits of data to be processed. The Data
Size field is a 21-bit signed number. Values written to this register are added to the current
register value. Multiple writes are allowed. The MDEU processes data when there is a positive
value in this register and there is data available in the MDEU input FIFO. Negative values can
occur during inbound processing, when it is necessary to hold back data from the MDEU until the
pad length has been decrypted.
Since the MDEU does not support bit offsets, the 3 least significant bits (lsbs) must be written as
0 and are always read as zero. Furthermore, when the CONT bit of the MDEU Mode Register is
set (1), the data size must be a multiple of the 512-bit block size (that is, the 9 lsbs must be
Table 26-2. Mode Register—HMAC or SSL-MAC Generated by Single Descriptor
Bits
Field
Value
for HMAC
for SSL-MAC
56
CONT
0 (off)
0 (off)
58
SMAC
0(on) 1(on)
59
INIT
1(on)
1(on)
60
HMAC
1(on) 0(on)
Table 26-3. Mode Register—HMAC Generated Across a Sequence of Descriptors
Bits
Field
Value
First Descriptor
Middle Descriptor(s)
Final Descriptor
56
CONT
1 (on)
1 (on)
0 (off)
59
INIT
1 (on)
0 (off)
0 (off)
60
HMAC
1 (on)
0 (off)
1 (on)
Summary of Contents for MSC8144E
Page 1: ...MSC8144E Reference Manual Quad Core Media Signal Processor MSC8144ERM Rev 3 July 2009 ...
Page 48: ...MSC8144E Reference Manual Rev 3 xlviii Freescale Semiconductor ...
Page 86: ...MSC8144E Reference Manual Rev 3 1 38 Freescale Semiconductor Overview ...
Page 168: ...MSC8144E Reference Manual Rev 3 3 60 Freescale Semiconductor External Signals ...
Page 242: ...MSC8144E Reference Manual Rev 3 5 26 Freescale Semiconductor Reset ...
Page 314: ...MSC8144E Reference Manual Rev 3 8 24 Freescale Semiconductor General Configuration Registers ...
Page 414: ...MSC8144E Reference Manual Rev 3 10 14 Freescale Semiconductor MSC8144E SC3400 DSP Subsystem ...
Page 452: ...MSC8144E Reference Manual Rev 3 11 38 Freescale Semiconductor Internal Memory Subsystem ...
Page 520: ...MSC8144E Reference Manual Rev 3 12 68 Freescale Semiconductor DDR SDRAM Memory Controller ...
Page 1070: ...MSC8144E Reference Manual Rev 3 21 28 Freescale Semiconductor Timers ...