Datasheet

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CnsLength = u2ModLength +12
For the Fast Reduction and Normalize:
RLength = u2ModLength +4
CnsLength = u2ModLength +8
For the BigRedMod:
RLength = u2ModLength +4
CnsLength =64
The following combinations of input values should be avoided in the case of a modular reduction ‘alone’,
meaning that it has not been requested as an option of any other command:
nu1ModBase, nu1CnsBase, nu1RBase, nu1XBase are not aligned on 32-bit boundaries
{nu1ModBase, u2ModLength + 4}, {nu1CnsBase, u2CnsLength}, {nu1XBase, 2*u2XLength + 8 + s}
or {nu1RBase, u2RLength} are not in Crypto RAM
u2ModLength is either: < 4, > 0xffc or not a 32-bit length
Overlaps exist between two or more of the areas: {nu1ModBase, u2ModLength + 4},{nu1CnsBase,
u2CnsLength}, {nu1XBase, 2*u2XLength + 8 + s} or {nu1RBase, u2RLength}
Note:  Overlaps between {nu1RBase, RLength} and {nu1XBase, 2*u2XLength + 8} are forbidden; but if
the operation is the Fast, Normalized or Big Modular Reduction, the equality between nu1RBase and
nu1XBase is authorized.
43.3.5.1.13 Status Returned Values
Table 43-49. RedMod Service Return Codes
Returned Status Importance Meaning
PUKCL_OK Service functioned correctly
PUKCL_DIVISION_BY_ZERO Severe When computing an Euclidean division, the
Modulus was found to be zero. This occurs ONLY
when either reducing using an Euclidean division
or computing the reduction constant usable for a
Fast or Normalize Reduction.
PUKCL_UNEXPLOITABLE_OPTIONS Severe A bad combination of options has been detected.
PUKCL_MALFORMED_MODULUS Severe The Msw of the modulus is not zero.
43.3.5.2 Modular Exponentiation (Without CRT)
43.3.5.2.1 Purpose
This service is used to perform the Modular Exponentiation computation. This service processes integers
in GF(p) only.
The options available for this service are:
Fast implementation
Regular implementation
Exponent is located in Crypto RAM or not in Crypto RAM
Exponent window size
SAM D5x/E5x Family Data Sheet
Public Key Cryptography Controller (PUKCC)
© 2019 Microchip Technology Inc.
Datasheet
DS60001507E-page 1491