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All overlapping between {nu1ModBase, u2ModLength + 4}, {nu1CnsBase, u2ModLength +8},
{nu1PointABase, 3*u2ModLength + 12}, {nu1PointBBase, 3*u2ModLength + 12} and
{nu1Workspace, 5*u2ModLength + 32}
43.3.6.3.7 Status Returned Values
Table 43-71. ZpEccAddFast Service Return Codes
Returned Status Importance Meaning
PUKCL_OK The computation passed without problem.
43.3.6.4 Fast Point Doubling
43.3.6.4.1 Purpose
This service is used to perform a Point Doubling, based on a given elliptic curve over GF(p).
43.3.6.4.2 How to Use the Service
43.3.6.4.3 Description
These two services process the Point Doubling:
Pt
C
= 2 × Pt
A
In this computation, the following parameters need to be provided:
A the input point is filled in projective coordinates (X,Y,Z) (pointed by {nu1PointABase,
3*u2ModLength + 12}). This point can be the Infinite Point.
Cns the Fast Modular Constant filled (pointed by {nu1CnsBase,u2ModLength +8})
P the modulus filled (pointed by {nu1ModBase,u2ModLength +4})
The workspace not initialized (pointed by {nu1WorkSpace, 4*u2ModLength +28}
The a parameter relative to the elliptic curve (pointed by {nu1ABase,u2ModLength +4})
The resulting C point is represented in projective coordinates (X,Y,Z) and is stored at the same
location than the input point A. This point can be the Infinite Point.
The service name for this operation is ZpEccDblFast. This service uses Fast mode and Fast Modular
Reduction for computations.
Important:  Before using this service, ensure that the constant Cns has been calculated with
the setup of the Fast Modular Reduction service.
43.3.6.4.4 Parameters Definition
Table 43-72. ZpEccDblFastService
Parameter Type Direction Location Data Length Before
Executing the
Service
After Executing
the Service
nu1ModBase nu1 I Crypto
RAM
u2ModLength + 4 Base of modulus
P
Base of modulus
P
nu1CnsBase nu1 I Crypto
RAM
u2ModLength + 8 Base of Cns Base of Cns
SAM D5x/E5x Family Data Sheet
Public Key Cryptography Controller (PUKCC)
© 2019 Microchip Technology Inc.
Datasheet
DS60001507E-page 1514