Datasheet

43.3.6.4.7 Status Returned Values
Returned Status Importance Meaning
PUKCL_OK – The computation passed without problem.
43.3.6.5 Fast Multiplying by a Scalar Number of a Point
43.3.6.5.1 Purpose
This service is used to multiply a point by an integral constant K on a given elliptic curve over GF(p).
43.3.6.5.2 How to Use the Service
43.3.6.5.3 Description
These two services process the Multiplying by a scalar number:
Pt
C
= K × 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, 8*u2ModLength +44}
• The a parameter relative to the elliptic curve (pointed by {nu1ABase,u2ModLength +4})
• K the scalar number (pointed by {nu1ScalarNumber,u2ScalarLength +4})
The resulting C point is represented in projective coordinates (X,Y,Z) and is stored at the very same place
than the input point A. This point can be the Infinite Point.
The service name for this operation is ZpEccMulFast. This service uses Fast mode and Fast Modular
Reduction for computations.
Note: Before using this service, ensure that the constant Cns has been calculated with the setup of the
Fast Modular Reduction service.
43.3.6.5.4 Parameters Definition
Table 43-73. ZpEccMulFast Service Parameters
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
u2ModLength u2 I – – Length of
modulus P
Length of
modulus P
nu1KBase nu1 I Crypto
RAM
u2KLength Scalar number
used to multiply
the point A
Unchanged
SAM D5x/E5x Family Data Sheet
Public Key Cryptography Controller (PUKCC)
© 2019 Microchip Technology Inc.
Datasheet
DS60001507E-page 1516