Implementation on FPGA - 2023.2 English

Vitis Libraries
Release Date
2023-12-20
Version
2023.2 English

We support OFB-DES, OFB-AES128, OFB-AES192, and OFB-AES256 modes in this implementation.

Attention

The bit-width of the interfaces we provide is shown as follows:

  plaintext ciphertext cipherkey IV
OFB-DES 64 64 64 64
OFB-AES128 128 128 128 128
OFB-AES192 128 128 192 128
OFB-AES256 128 128 256 128

The algorithm flow chart is shown as follow:

algorithm flow chart of OFB

As we can see from the chart, both encryption and decryption part of OFB mode has dependencies, so the input block of each iteration (except for iteration 0) needs a feedback data from its last iteration. Thus, the initiation interval (II) of OFB mode cannot achieve an II = 1.