MPC180LMB Freescale Semiconductor, MPC180LMB Datasheet - Page 80

• Manufacturer Part Number: MPC180LMB
• Description: IC SECURITY PROCES 66MHZ 100LQFP
• Manufacturer: Freescale Semiconductor

Specifications of MPC180LMB

• Processor Type: Security Processor
• Speed: 66MHz
• Voltage: 1.8V
• Mounting Type: Surface Mount
• Package / Case: 100-LQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Features: -

RSA Routines
7.4.5 RSA F
Modular addition may be performed on any two vectors loaded into A (A0-A3) and B
(B0-B3), where both of these vectors are less than the value stored in the modulus register
N (N0-N3). This is accomplished by computing A-B if A > B or A-B+N if A < B. The
results are stored in the respective B register. This function is particularly helpful when
using the Chinese Remainder Theorem. This function operates with a minimum of 4 digits
(Modsize = 3).
Prior to initiating this function, the A and B register pointers must be set in the control
register which indicate which sub-registers (e.g A0, B0, A1, B1, etc.) are the targeted
operands. See Table 7-2 for a detailed description. Once this is performed, the host
processor may successfully initiate this function.
Computation
Entry name
Entry address
Pre-conditions
Post-conditions
Special
conditions
7-30
C = D - E mod N, where D, E, and C are integers and are less than N
modularsubtract
0x009(modularsubtract)
A0-3 = D
B0-3 = E
N0-3 = modulus
B0-3 = results of modular subtraction stored where the B operand was located
Unless explicitly noted, all other registers are not guaranteed to be any particular value.
The function operates the same regardless of whether or not the operands are in the Montgomery
residue system.
p
Initial Condition
Figure 7-21. Modular Subtract Register Usage
Modular Subtract
‘0’ - integer-modulo-n enabled
Freescale Semiconductor, Inc.
MPC180LMB Security Processor User’s Manual
modulus N( )
For More Information On This Product,
‘0’ - ECC disabled
Table 7-22. Modular Subtract
D( )
E( )
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set (00)
set (00)
set (00)
set
EXP(k)_SIZE
Modsize
regAsel
regBsel
regNsel
EXP(k)
XYZ
ECC
F2M
B3
B2
B1
B0
A3
A2
A1
A0
N3
N2
N1
N0
Modular Subtract
same
same
same
same
same
C( )
modulus N( )
same
Final Condition