GD32W51x User Manual
985
Table 29-6. Range of parameters used by ECC scalar multiplication
Param eters
Range
input
Length of scalar
multiplier k (LEN)
0<LEN≤640
Modulus length M
0<M≤640
Sign of curve
coefficient a
0x0: positive
0x1: negative
Curve coefficient |a|
Absolute value |a|
<
p
Curve modulus p
Odd prime
0<p≤2
M
scalar multiplier k
0≤k< 2
LEN
(k < n, and n is the curve prime order)
x coordinate of point P
x
P
<p
y coordinate of point P
y
P
<p
output
x coordinate of point kP
x
<p
y coordinate of point kP
y<p
If k=0, the output is a point at infinity. When k is a multiple of curve prime order n, the output
will also be a point at infinity. In this module, output is (0, 0) if the result is a point at infinity.
If k<0, the absolute value of k replaces k as the scalar multiplier for ECC scalar multiplication.
After the computation is completed, -P = (x, -y) can be used to compute the final result of y.
ECDSA sign
The ECDSA sign operation is selected by configuring MODSEL[5:0] in PKCAU_CTL register
as "100100". The operation declaration is shown in
.