Datasheet

Verify = EcDsaVerifySignature(Pt
A
, HashVal, Signature, CurveParameters, PublicKey)
The points used for this operation are represented in different coordinate systems. In this computation,
the following parameters need to be provided:
• A the input point is filled with the affine values (X,Y) and Z = 1 (pointed by{nu1PointABase,
3*u2ModLength + 12})
• Cns the working space for the Fast Modular Constant not initialized (pointed by
{nu1CnsBase,u2ScalarLength + 8})
• P the modulus filled (pointed by {nu1ModBase,u2ModLength +4})
• The workspace not initialized (pointed by {nu1WorkSpace, 8*u2ModLength +44} The a and b
parameters relative to the elliptic curve (pointed by {nu1ABase,2*u2ModLength + 8})
• The order of the Point A on the elliptic curve (pointed by {nu1OrderPointBase,u2ScalarLength +4})
• HashVal the hash value beforehand generated and filled (pointed by {nu1HashBase,u2ScalarLength
+4})
• The Public Key point is filled in “mixed” coordinates (X,Y) with the affine values and Z = 1 (pointed by
{nu1PointPublicKeyGen, 3*u2ModLength + 12})
• The input signature (R,S), even if it is not a Point, is represented in memory like a point in affine
coordinates (X,Y) (pointed by {nu1PointSignature, 2*u2ScalarLength + 8})
Important: For the ECDSA signature verification be sure to follow the directives given for
the RNG on the chip you use (particularly initialization, seeding) and compulsorily start the
RNG.
• The operation consists in obtaining a V value with all these input parameter and check that V equals
the provided R. If all is correct and the signature is the good one, the status is set to PUKCL_OK. If
all is correct and the signature is wrong, the status is set to PUKCL_WRONG_SIGNATURE. If an
error occurs, the status is set to the corresponding error value (see Status Returned Values below).
The service name for this operation is GF2NEcDsaVerifyFast. This service uses Fast mode and Fast
Modular Reduction for computation.
43.3.7.10.4 Parameters Definition
Table 43-110. GF2NEcDsaVerifyFast 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
u2ScalarLength
+ 8
Base of Cns Base of Cns
u2ModLength u2 I – – Length of
modulus P
Length of
modulus P
nu1OrderPointBase nu1 I Crypto
RAM
u2ScalarLength
+ 4
Order of the
Point A in the
elliptic curve
Unchanged
SAM D5x/E5x Family Data Sheet
Public Key Cryptography Controller (PUKCC)
© 2019 Microchip Technology Inc.
Datasheet
DS60001507E-page 1564