Geehy SEMICONDUCTOR APM32F405 Series, User Manual

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efficiency of the process. The generating program and verification program of
digital signature need to use the same hash algorithm.
SHA-1 and MD5 are secure because of failing to find the corresponding
message of a certain specified message digest or two different messages that
generate the same message digest. Modifying a message being transmitted
may result in a different message digest so that the signature cannot be verified.
The message or data file processed by the hash processor is called bit string.
The length of a message is the number of its bit. 32 bits of this bit string can be
regarded as one word. An important point for stuffing is that the bit string grows
from left to right, and the bits can be divided into bytes or words.
Register address mapping
Table 81 HASH Register Address Mapping
Register name Description Offset address
HASH_CTRL HASH control register 0x00
HASH_INDATA HASH input data register 0x04
HASH_START HASH start register 0x08
HASH_DIGx HASH digest register x 0x0C+
（
x*0x04
） ，
x=0…4
HASH_INT HASH interrupt register 0x20
HASH_STS HASH state register 0x24
HASH_CTSWAPx HASH exchange context register x 0xF8+
（
x*0x04
） ，
x=0…50
Register functional description
HASH control register (HASH_CTRL)
Offset address: 0x00
Reset value: 0x0000 0000
Field Name R/W Description
1:0 Reserved
2 INITCAL R/W
Initialize Message Digest Calculation
Writing 1 to this bit will reset the hash processor core so that the
hash can calculate a new message digest.
Writing 0 to this bit has no effect. Reading this bit will always return
0.
3 DMAEN R/W
DMA Enable
0: Disable
1: Enable. When the hash core can receive data, a DMA request
will be sent.
Note: