MSC8144E Reference Manual, Rev. 3
26-10
Freescale
Semiconductor
Security Engine (SEC)
For test purposes, the core processor can also write keys, context, and text-data directly to
execution units, using SEC core processor-controlled access. This method avoids using
descriptors.
26.2.1.1.1 Descriptor Structure
SEC descriptors are conceptually similar to descriptors used by most devices with DMA
capability. The descriptors have a fixed length of 64 bytes. A descriptor consists of one header (8
bytes) and seven pointers (each 8 bytes), as seen in Figure 26-4.
The header specifies the security operation to perform, the needed execution unit(s), and the
modes for each execution unit. The pointers, all of which have the same format, contain pointer
and length information for locating input or output data parcels (such as keys, context, or
text-data). The large number of pointers provided in the descriptor allows for multi-algorithm
operations that require fetching of multiple keys, as well as fetch and return of contexts. Any
pointer that is not needed can be given a length of zero, and the channel skips over the
corresponding operations.
SEC descriptors include scatter/gather capability, which means that each pointer in a descriptor
can be either a direct pointer to a contiguous parcel of data, or can be a pointer to a link table
which is a list of pointers and lengths used to assemble the data parcel. When a link table is used
to read input data, this is referred to as a gather operation; when used to write output data, it is
referred to as a scatter operation.
63
48
47
46
40 39 36 35
32 31
0
Header
Header
Reserved
Pointer 0
Length0
J0
Extent0
—
Eptr0
Pointer0
Pointer 1
Length1
J1
Extent1
—
Eptr1
Pointer1
Pointer 2
Length2
J2
Extent2
—
Eptr2
Pointer2
Pointer 3
Length3
J3
Extent3
—
Eptr3
Pointer3
Pointer 4
Length4
J4
Extent4
—
Eptr4
Pointer4
Pointer 5
Length5
J5
Extent5
—
Eptr5
Pointer5
Pointer 6
Length6
J6
Extent6
—
Eptr6
Pointer6
Figure 26-4. Descriptor Format
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 ...