![](http://datasheet.mmic.net.cn/Freescale-Semiconductor/MPC184VFB_datasheet_99025/MPC184VFB_8.png)
8
MPC184 Security Processor Technical Summary
MOTOROLA
by eld or modulus size. For example, a eld size of 160 is roughly equivalent to the security provided by
1024 bit RSA. A eld size set to 208 roughly equates to 2048 bits of RSA security.
The PKEU contains routines implementing the atomic functions for elliptic curve processing—point
arithmetic and nite eld arithmetic. The point operations (multiplication, addition and doubling) involve
one or more nite eld operations which are addition, multiplication, inverse, and squaring. Point add and
double each use of all four nite eld operations. Similarly, point multiplication uses all EC point operations
as well as the nite eld operations. All these functions are supported both in modular arithmetic as well as
polynomial basis nite elds.
7.1.2 Modular Exponentiation Operations
The PKEU is also capable of performing ordinary integer modulo arithmetic. This arithmetic is an integral
part of the RSA public key algorithm; however, it can also play a role in the generation of ECC digital
signatures and Dife-Hellman key exchanges.
Modular arithmetic functions supported by the MPC184’s PKEU include the following:
R 2 mod N
A’ E mod N
(A
x B) R -1 mod N
(A
x B) R -2 mod N
(A+B) mod N
(A-B) mod N
Where the following variable denitions: A’ = AR mod N, N is the modulus vector, A and B are input
vectors, E is the exponent vector, R is 2 s, where s is the bit length of the N vector rounded up to the nearest
multiple of 32.
The PKEU can perform modular arithmetic on operands up to 2048 bits in length. The modulus must be
larger than or equal to 129 bits. The PKEU uses the Montgomery modular multiplication algorithm to
perform core functions. The addition and subtraction functions exist to help support known methods of the
Chinese Remainder Theorem (CRT) for efcient exponentiation.
7.2
Data Encryption Standard Execution Unit (DEU)
The DES execution unit (DEU) performs bulk data encryption/decryption, in compliance with the Data
Encryption Standard algorithm (ANSI x3.92). The DEU can also compute 3DES and extension of the DES
algorithm in which each 64-bit input block is processed three times. The MPC184 supports 2 key (K1=K3)
or 3 key 3DES.
The DEU operates by permuting 64-bit data blocks with a shared 56-bit key and an initialization vector (IV).
The MPC184 supports two modes of IV operation: ECB (Electronic Code Book) and CBC (Cipher Block
Chaining).
7.3 Arc Four Execution Unit (AFEU)
The AFEU accelerates a bulk encryption algorithm compatible with the RC4 stream cipher from RSA
Security, Inc. The algorithm is byte-oriented, meaning a byte of plain text is encrypted with a key to produce
a byte of ciphertext. The key is variable length and the AFEU supports key lengths from 40 to 128 bits (in
byte increments), providing a wide range of security strengths. RC4 is a symmetric algorithm, meaning each
of the two communicating parties share the same key.
F
re
e
sc
a
le
S
e
m
ic
o
n
d
u
c
to
r,
I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
n
c
..
.