Datasheet

43.3.5.1.8 Fast Modular Reductions Service Parameters Definition
Table 43-45. Fast RedMode and Normalize Service Parameters
Parameter Type Direction Location Data Length Before
Executing the
Service
After Executing
the Service
u2Options u2 I – – Options (see
below)
Options (see
below)
Specific/CarryIn Bits I – – Must be set to
zero.
–
Specific/Gf2n Bit I – – GF(2n) Bit –
Specific/
CarryOut Zero
Violation
Bits I – – – Carry Out, Zero
Bit and Violation
Bit filled
according to the
result
nu1ModBase
(see Note 1)
nu1 I Crypto
RAM
u2ModLength + 4 Base of N Base of N
untouched
nu1CnsBase nu1 I Crypto
RAM
u2ModLength
+ 12
Base of Cns Base of Cns
untouched
u2ModLength u2 I – – Length of N Length of N
nu1RBase (see
Note 2)
nu1 I Crypto
RAM
u2ModLength + 4 Base of R Base of R filled
with the result
nu1XBase (see
Note 3)
nu1 I Crypto
RAM
2*u2ModLength
+ 8
Base of X the
number to
reduce
Base of X
corrupted
Note:
1. The Modulus is to be given as a u2ModLength Aligned Significant Length Bytes however, it has to
be provided as a u2ModLength + 4 bytes long number, having the four high-order bytes set to zero.
2. To make profitable the space memory, it is possible to set nu1RBase exactly equal to nu1XBase.
3. After the X (pointed by {nu1XBase,2 * u2ModLength + 8}) MSB bytes, supplementary bytes will be
saved/restored (8 bytes in case of Fast RedMod, otherwise; 12 bytes). These supplementary bytes
may be entirely in the Crypto RAM (therefore, do not place the X area too near the end of the
Crypto RAM) and shall not overlap with other area used by the service.
43.3.5.1.9 Big Modular Reduction Parameters Definition
Table 43-46. Big RedMod Service Parameters
Parameter Type Direction Location Data Length Before
Executing the
Service
After Executing
the Service
u2Options u2 I – – Options (see
below)
Options (see
below)
SAM D5x/E5x Family Data Sheet
Public Key Cryptography Controller (PUKCC)
© 2019 Microchip Technology Inc.
Datasheet
DS60001507E-page 1488