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ECC Routines
Computation
R = P + Q, where R ≡ (X
Entry name
F
maddPtoQ
2
Entry address
0x005(F
maddPtoQ)
2
Pre-conditions
A0 = X'
(projective coordinate in Montgomery residue system)
1
A1 = Y'
(projective coordinate in Montgomery residue system)
1
A2 = Z'
(projective coordinate in Montgomery residue system)
1
A3 = a' (elliptic curve parameter in Montgomery residue system)
B0 = c' (elliptic curve parameter in Montgomery residue system)
B1 = X'
(projective coordinate in Montgomery residue system)
2
B2 = Y'
(projective coordinate in Montgomery residue system)
2
B3 = Z'
(projective coordinate in Montgomery residue system)
2
N0 = irreducible polynomial of the ECC system
Post-conditions
A0 = X'
1
A1 = Y'
1
A2 = Z'
1
A3 = a'
B0 = c'
B1 = X'
3
B2 = Y'
3
B3 = Z'
3
Unless explicitly noted, all other registers are not guaranteed to be any particular value.
Special
conditions
The c elliptic curve parameter is a function of the 'b' parameter and field size:
All variables followed with the tick mark (') indicate it is in the Montgomery residue system.
Initial Condition
Figure 7-12. ECC F
7-20
PRELIMINARY—SUBJECT TO CHANGE WITHOUT NOTICE
Table 7-13. ECC F
2
F
2
,Y
,Z
), P ≡ (X
,Y
3
3
3
1
B3
Z'
2
B2
Y'
2
B1
X'
2
B0
c'
a'
A3
Z'
A2
1
Y'
A1
1
X'
A0
1
N3
N2
N1
N0
irred. poly.
ECC
'1' - ECC enabled
EXP(k)
XYZ
'1' - F
m enabled
F2M
2
Modsize
set
EXP(k)_SIZE
m Point Add Register Usage
2
MPC180E Security Processor User's Manual
m Point Add
m Point Add
, Z
), and Q ≡ (X
,Y
, Z
)
1
1
2
2
2
Final Condition
Z'
3
Y'
3
X'
3
c'
a'
Z'
1
Y'
1
X'
1
?
?
?
irred. poly.
same
same
same
m 2
–
2
.
c
=
b
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