Datasheet

43.3.6.5.7 Status Returned Values
Returned Status Importance Meaning
PUKCL_OK – The computation passed without problem.
43.3.6.6 Quick Dual Multiplying by Two Scalar Numbers and Two Points
43.3.6.6.1 Purpose
This service is used to multiply two points by two integral constants K1 and K2, and then provide the
addition of these multiplications results.
Important: This service has a quick implementation without additional security.
43.3.6.6.2 How to Use the Service
43.3.6.6.3 Description
This service processes the dual Multiplying by two scalar numbers:
PtC = K
1
× Pt
A
+ K
2
× Pt
B
In this computation, the following parameters need to be provided:
• A the first input point is filled in projective coordinates (X,Y,Z) (pointed by {pu1PointABase,
(3*(u2ModLength + 4)) * (2(WA-2))}). This point can be the Infinite Point.
• B the 2nd input point is filled in projective coordinates (X,Y,Z) (pointed by {pu1PointBBase,
(3*(u2ModLength + 4)) * (2(WB-2))}). This point can be the Infinite Point.
• P the modulus filled and Cns the Fast Modular Constant filled (pointed by {pu1ModCnsBase,
2*u2ModLength + 16})
• The a parameter filled and the workspace not initialized (pointed by {pu1AWorkBase,
9*u2ModLength +48}
• KAB the scalar numbers (pointed by {pu1KABBase, 2*u2KLength +8})
• The options are set by the u2Options input parameter, which is composed of:
– wA: Size of window for Point A between 2 and15
– wB: Size of window for Point B between 2 and15
– PUKCL_ZPECCMUL_SCAL_IN_CLASSIC_RAM flag: to set only if the scalars are entirely in
Classic RAM with no part in PUKCC RAM
The resulting C point is represented in projective coordinates (X,Y,Z) and is stored at (pu1AWorkBase +
u2ModLength + 4). This point can be the Infinite Point.
Important: Before using this service, ensure that the constant Cns has been calculated with
the setup of the Fast Modular Reduction service.
43.3.6.6.4 Parameters Definition
WA is the Point A window size and WB is the Point B window size (see Options below for details).
SAM D5x/E5x Family Data Sheet
Public Key Cryptography Controller (PUKCC)
© 2019 Microchip Technology Inc.
Datasheet
DS60001507E-page 1518