SH7670 Datasheet, PDF (558/1292 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7670 Series

Section 14 DMAC That Works with Encryption/Decryption and Forward Error Correction Core (A-DMAC)
14.3.1 DMAC Channel Function
The A-DMAC has two DMAC channels for checksum processing processing.
Table14.6 AES Operation Cycles
Key Length
128 bits
192 bits
256 bits
Encryption Cycle
10
12
14
Decryption Cycle
20
22
24
Table14.7 Encryption Operating Modes
Mode Name
ECB
(Electronic Codebook
Mode)
CBC
(Cipher Block
Chaining Mode)
CFB
(Cipher Feedback
Mode)
OFB
(Output Feedback
Mode)
Description
Mode in which to input one block of plain text (ciphertext) and generate the
corresponding ciphertext (plain text).
In ECB, parallel processing is possible because processing per block is
independent. In this mode, however, security is not high because the same
ciphertext is output for a combination of the same plain text data and
encryption keys.
Mode in which to generate ciphertext by XORing plain text with the
immediately preceding encrypted block to encrypt the block.
In the first block, the initial vector (IV) is XORed with plain text. You do not
need to keep the IV confidential but need to change it when using the
same encryption key. Decryption is performed in reverse order of
encryption. This mode does not support parallel processing.
Mode in which to encrypt the ciphertext generated in the immediately
preceding block and XOR the block with plain text to obtain new ciphertext.
The first block processing encrypts the IV and XORs it with plain text to
obtain ciphertext. Decryption processing encrypts ciphertext and XORs it
with the ciphertext of the next block to obtain plain text. Like this, CFB
decryption processing is achieved via encryption operation. However, this
mode does not support parallel processing.
Mode in which to encrypt the immediately preceding encryption block and
XOR the obtained block with plain text (ciphertext) to generate ciphertext
(plain text).
The first block processing uses the IV. OFB decryption processing is
achieved via encryption operation. However, this mode does not support
parallel processing.
Rev. 1.00 Nov. 14, 2007 Page 532 of 1262
REJ09B0437-0100