RM0090: Reference manual - STMicroelectronics

RM0090 Hash processor (HASH)
Figure 220. Bit, byte and half-word swapping
A-In case of binary data hash, all bits should be swapped as below
Bit s w a p pi n g ope r a t i o n
H A S H_D I N
bit string organization in
Hash processor: Big-Endian
b i t 3 1
B y t e s w a p ping ope r a t i o n
H A S H_D I N
HA S H_ D I N
bi t 0 bi t 1 bi t 2 9 b i t 3 0 b i t 3 1
B y t e 3
bi t s 7 . . . 0
B y t e 0
bi t s 7 . . . 0
bi t 3 0
B y t e 2
b i t s 7 .. . 0
B y t e 1
b i t s 7 .. . 0
bi t 2
B y t e 1
b i t s 7 .. . 0
B y t e 2
b i t s 7 .. . 0
bi t 1
bi t 0
B y t e 0
bi t s 7 . . . 0
B y t e 3
bi t s 7 . . . 0
b i t- s tr i n g g r o ws
i n t hi s di rect io n
as d e f i n e d b y
FIPS PUB 1 80 - 2 s t d .
b i t- s tr i n g g r o ws
i n t hi s di rect io n
as d e f i n e d b y
FIPS PUB 1 80 - 2 s t d .
C-In case of half-word hash, all half-word should be swapped as below
H a l f - w o r d s w a pping o p er a t io n
D A T A T YPE = bx 01
Half-wo r d 1
bi t s 15 . . . 0
Half-wor d 0
bi t s 15 .. . 0
Half-wo r d 0
bi t s 15 . . . 0
Half-wor d 1
bi t s 15 .. . 0
“1”
D A T A TYPE = bx 1 1
Bits entred with little-Endian format
p ad d ing is perfo r m ed
on this side of the
bit s t ri n g.
B-In case of byte data hash, all bytes should be swapped as below
Bit string organization in
Hash processor: Big-Endian
Bit string organization in
Hash processor: Big-Endian
D A T A T YPE = bx 10
Bytes entred with little-Endian format
half word entred with little-Endian format
b i t-str in g g r o ws
i n t h is d i rect i o n
a s d e fi n e d b y
F I PS PUB 18 0 - 2 s t d .
ai16082
Doc ID 018909 Rev 3 598/1416