SEC Lite Overview
MPC885 PowerQUICC Family Reference Manual, Rev. 2
46-6
Freescale Semiconductor
The DEU operates by permuting 64-bit data blocks with a shared 56-bit key and an initialization vector
(IV). The SEC Lite supports two modes of IV operation: Electronic Code Book (ECB) and Cipher Clock
Chaining (CBC).
46.9.2
Advanced Encryption Standard Execution Unit (AESU)
The AESU is used to accelerate bulk data encryption/decryption in compliance with the Advanced
Encryption Standard algorithm Rijndael. The AESU executes on 128-bit blocks with a choice of key sizes:
128, 192, or 256 bits.
AESA is a symmetric-key algorithm, the sender and receiver use the same key for both encryption and
decryption. The session key and IV are supplied to the AESU module prior to encryption. The processor
supplies data to the module that is processed as 128 bit input. The AESU operates in ECB, CBC, and
counter modes.
46.9.3
Message Digest Execution Unit (MDEU)
The MDEU computes a single message digest (or hash or integrity check) value of all the data presented
on the input bus, using either the MD5, SHA-1 or SHA-256 algorithms for bulk data hashing. With any
hash algorithm, the larger message is mapped onto a smaller output space, therefore collisions are possible,
albeit not probable. The 160-bit hash value is a sufficiently large space such that collisions are extremely
rare. The security of the hash function is based on the difficulty of locating collisions. That is, it is
computation infeasible to construct two distinct but similar messages that produce the same hash output.
•
The MD5 generates a 128-bit hash, and the algorithm is specified in RFC 1321.
•
SHA-1 is a 160-bit hash function, specified by the ANSI X9.30-2 and FIPS 180-1 standards.
•
SHA-256 is a 256-bit hash function that provides 256 bits of security against collision attacks.
•
The MDEU also supports HMAC computations, as specified in RFC 2104.
46.10 Performance Estimates
Bulk encryption/authentication performance estimates shown in
Table 46-2
include data/key/context reads
(from memory to the SEC Lite), security processing (internal to the SEC Lite), and writes of completed
data/context to memory by the SEC Lite, using typical MPC885 system overhead.
Table 46-2. Estimated Bulk Data Encryption Performance (Mbps)
DES
CBC
3DES
CBC
AES 128
AES 256
MD5
SHA-1
3DES/
HMAC-
SHA-1(Rx)
64 byte
43
36
38
32
38
34
29
128 byte
75
55
60
51
66
59
50
256 byte
119
76
83
70
100
87
74
512 byte
173
95
104
88
135
114
94
Summary of Contents for PowerQUICC MPC870
Page 98: ...MPC885 PowerQUICC Family Reference Manual Rev 2 I 4 Freescale Semiconductor ...
Page 118: ...MPC885 Overview MPC885 PowerQUICC Family Reference Manual Rev 2 1 20 Freescale Semiconductor ...
Page 158: ...The MPC8xx Core MPC885 PowerQUICC Family Reference Manual Rev 2 3 18 Freescale Semiconductor ...
Page 288: ...MPC885 PowerQUICC Family Reference Manual Rev 2 III 4 Freescale Semiconductor ...
Page 554: ...MPC885 PowerQUICC Family Reference Manual Rev 2 V 6 Freescale Semiconductor ...
Page 1090: ...UTOPIA Interface MPC885 PowerQUICC Family Reference Manual Rev 2 43 8 Freescale Semiconductor ...
Page 1312: ...Byte Ordering MPC885 PowerQUICC Family Reference Manual Rev 2 A 8 Freescale Semiconductor ...
Page 1336: ...MPC885 PowerQUICC Family Reference Manual Rev 2 D 16 Freescale Semiconductor ...
Page 1358: ...MPC885 PowerQUICC Family Reference Manual Rev 2 D 38 Freescale Semiconductor ...
Page 1370: ...MPC880 MPC885 PowerQUICC Family Reference Manual Rev 2 E 4 Freescale Semiconductor ...
Page 1386: ...Revision History MPC885 PowerQUICC Family Reference Manual Rev 2 I 2 Freescale Semiconductor ...