
Symmetric Key Hardware Accelerator (SKHA)
35-2
Freescale Semiconductor
DES is a block cipher that uses a 56-bit key (64 bits with CRC) to encrypt 64-bit blocks of data, one block
at a time. A conceptual diagram of this process is shown in
. DES is a symmetric algorithm, so
each of the two communicating parties share the same 64-bit key for encryption and decryption. DES
processing begins after this shared session key is agreed upon. The text or binary message to be encrypted
(typically called plaintext) is partitioned into
n
sets of 64-bit blocks. Each block is processed, in turn, by
the DES engine, producing
n
sets of encrypted (ciphertext) blocks. These blocks may be transmitted to the
other entity.
Decryption is handled in the reverse manner. The ciphertext blocks are processed one at a time by a DES
module in the recipient’s system. The same key is used, and the DES block manages the key processing
internally so that the plaintext blocks are recovered.
Figure 35-1. DES Encryption Process
In addition, the SKHA module can compute 3DES, which is an extension to the DES algorithm whereby
every 64-bit input block is processed three times. The SKHA supports two key (K1=K3) or three key
3DES. A diagram of 3DES is shown in
Figure 35-2. Triple-DES Encryption Process (ECB Mode)
35.1.1.2
Advanced Encryption Standard (AES) Algorithm
In AES mode, SKHA is used to accelerate bulk data encryption/decryption in compliance with the
advanced encryption standard algorithm (AESA) Rinjdael. AES executes on 128-bit blocks with 128-bit
key size.
AES is a symmetric key algorithm, the sender and receiver use the same key for encryption and decryption.
The session key and initialization vector (CBC mode) are supplied to the SKHA module prior to
...
DES
64-bit key
64-bit
block 1
64-bit
block 2
64-bit
block n-1
64-bit
block n
...
64-bit
block 1
64-bit
block 2
64-bit
block n-1
64-bit
block n
Plaintext blocks
Ciphertext blocks
Plaintext blocks
DES
1
64-bit K
1
DES
2
64-bit K
2
DES
3
64-bit K
3
64-bit
block 1
64-bit
block n
64-bit
block 1
64-bit
block n
Plaintext blocks
Ciphertext blocks
MCF5329 Reference Manual, Rev 3
Summary of Contents for MCF5329
Page 106: ...ColdFire Core 3 32 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 148: ...Cache 5 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 154: ...Static RAM SRAM 6 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 184: ...Power Management 8 18 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 204: ...Reset Controller Module 10 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 220: ...System Control Module SCM 11 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 228: ...Crossbar Switch XBS 12 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 268: ...General Purpose I O Module 13 40 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 392: ...SDRAM Controller SDRAMC 18 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 436: ...Fast Ethernet Controller FEC 19 44 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 594: ...FlexCAN 23 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 678: ...Pulse Width Modulation PWM Module 26 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 684: ...Watchdog Timer Module 27 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 704: ...DMA Timers DTIM0 DTIM3 29 12 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 754: ...UART Modules 31 34 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 770: ...I2 C Interface 32 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 866: ...Debug Module 36 50 Freescale Semiconductor MCF5329 Reference Manual Rev 3...