8201, 8202, 8203, 8204 Acceleration Processor Data Sheet, DS-0157-05
Page 57
Exar Confidential
3.1.2.5
Desc_cmd_hash
This descriptor defines the hash engine related parameters. Desc_cmd_hash is 8 bytes for
either 32-bit or 64-bit addressing modes.
During a Slice Hash operation, the Hash engine will calculate the hash value for every slice
of data. A single Slice Hash operation must contain more than one slice. The size of one
slice data is defined by Slice_Size[15:0].
During a File Hash operation, the Hash engine calculates one hash value for the entire file.
File Hash operations may be stateless or stateful. For a stateless file hash operation, one
command operates on data from one file and the “file hash chaining value” of this
command is the “File Hash” of the file (see
Section 3.1.3.6). For a stateful file hash
operation, one data file is operated on by several commands, and each command is
assigned a file hash chaining value by the 820x. The file hash chaining value of the prior
final command is used as the “File hash” of the file.
ENC_CM
50
Encryption Count Mode.
If this bit is set to zero, the encryption source count
in the 820x begins to decrement after the last
header byte has been passed through the 820x. If
this bit is set to one, the encryption source counter
begins to decrement after the last byte processed
by the previous processing engine. Please refer to
information.
0
820x begins to decrement the encryption source
count after the last header byte
1
820x begins to decrement the encryption source
count after the last byte processed by the
previous processing engine
Reserved
4
0
Reserved.
ENC_AG[3:0]
3:0
0
Encryption Algorithm.
0000 AES-GCM
Hash engine should be set to AES-GCM-MAC
algorithm
0001 AES-CBC
0010 AES-CTR
0011 AES-ECB
0100 AES-XTS
Compression Engine must be disabled and
Hash_OP[1:0] cannot be set any type of MAC
operation
01013DES
All other settings are reserved.
Note: GMAC operations use the AES algorithm. If
sharing logic with other AES modes, the GMAC will
be implemented in the Encryption Engine.
Field Name
Bits
Default Description