Datasheet

43.3.7.6.7 Status Returned Values
Table 43-103. GF2NEcConvAffineToProjective Service Return Codes
Returned Status Importance Meaning
PUKCL_OK – The computation passed without problem.
43.3.7.7 Randomize Coordinate
43.3.7.7.1 Purpose
This service is used to convert the Projective representation of a point to another Projective
representation.
43.3.7.7.2 How to Use the Service
43.3.7.7.3 Description
The operation performed is:
Projective(X
1
, Y
1
, Z
1
) → Projective(X
2
, Y
2
, Z
2
)
In this computation, the following parameters need to be provided:
• The input point is filled in projective coordinates (X,Y,Z) (pointed by {nu1PointBase,3*u2ModLength
+ 12}). This Point must not be the point at infinity.
• 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, 3*u2ModLength + 28}
• The random number (pointed by {nu1RandomBase, u2ModLength + 4}) The result is the point
nu1PointBase with its (X,Y,Z) coordinates randomized. The service for this operation is
GF2NEcRandomiseCoordinate.
Important:
Before using this service:
• Ensure that the constant Cns has been calculated with the Setup of the fast Modular
Reductions service.
• Be sure to follow the directives given for the RNG on the chip you use (particularly
initialization, seeding) and compulsorily start the RNG.
43.3.7.7.4 Parameters Definition
Table 43-104. GF2NEcRandomiseCoordinate 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
SAM D5x/E5x Family Data Sheet
Public Key Cryptography Controller (PUKCC)
© 2019 Microchip Technology Inc.
Datasheet
DS60001507E-page 1556