Table of Contents
Advertisement
7.3.6 ECC F
Montgomery Modular Multiplication
p
((A × B × R
-1
The (A × B × R
) mod N calculation is the core function of the PKEU. It is used to assist
the point add and double routines in completing their functions. For ECC purposes, this
function will rarely be used directly by the host processor. This function operates with a
minimum of five digits (Modsize = 4). The complete set of I/O conditions is shown below:
Computation
C = A * B * R
number of digits of the modulus vector
Entry name
modularmultiply
Entry address
0x00a(modularmultiply)
Pre-conditions
A0-3 = A (integer, exact A-location pre-selected in Control Register)
B0-3 = B (integer, exact B-location pre-selected in Control Register)
N0-3 = prime p (modulus) of the ECC system
Post-conditions
A0-3 = A operand is preserved
B0-3 = results of modular multiplication stored where the B operand was located
Unless explicitly noted, all other registers are not guaranteed to be any particular value.
Special
Typically, though it is not mandatory, the operands will be in the Montgomery residue system. The
conditions
only time this would not be the case is when manually placing a value into the Montgomery residue
system.
Initial Condition
modulus N (if N0 selected)
Figure 7-9. Modular Multiplication Register Usage
PRELIMINARY—SUBJECT TO CHANGE WITHOUT NOTICE
-1
) mod N)
Table 7-10. Modular Multiplication
-1
mod N, where A, B, and C are integers less than N and R = 2
B3
B2
B1
B0
B (if B0 selected)
A3
A2
A1
A (if A0 selected)
A0
N3
N2
N1
N0
ECC
'1' - ECC enabled
EXP(k)
XYZ
F2M
'0' - F
enabled
p
regAsel
set (00, 01, 10, 11)
regBsel
set (00, 01, 10, 11)
regNsel
set (00, 01, 10, 11)
Modsize
set
EXP(k)_SIZE
Chapter 7. Public Key Execution Unit
Modular Multiply
Final Condition
?
?
?
C (if B0 selected)
A (if A0 selected)
?
?
?
modulus N (if N0 selected)
same
same
same
same
same
same
ECC Routines
16D
where D is the
7-15
Advertisement
Table of Contents
