This code is part of our final project for CS 3220 A: Processor Design in Spring 2022 with Dr. Hyesoon Kim. Siddhant and I worked with Yonghae to create an implementation of the Qarma Cipher in hardware. This code was wrapped in an execution unit and integrated into the BOOM Core. The module was used to provide pointer signing primitives as an extension to the RISC-V instruction set.
- Modified BOOM Core
- CARRV 2022 Paper (not available)
The code, like BOOM, is written in a Scala DSL called Chisel. It has to be
compiled to Verilog (or FIRRTL). Pre-compiled output is available under
Releases. Alternatively, the code can be compiled using sbt by running
$ sbt run
in the root of this project. The compiler also takes command-line options, perhaps most usefully one to set the output directory. All the options can be listed with
$ sbt "run --help"
Regardless, the top module of the compiled HDL is called QarmaHW. It
implements five-rounds with the s1 S-Box and M = Q = M42.
Four of the ports on the QarmaHW module are used to specify the key.
Specifically, the
key_k0,key_k1,key_w0, andkey_w1
ports must each be connected to their corresponding parameter. Note that k1
and w1 must be set explicitly. Set them according to the computation in the
paper for encryption or decryption.
Both the input and output are wrapped inside a ready/valid interface. For the
input, assert inp_valid when it's valid. On the first clock cycle where both
that and inp_ready are asserted, the module has latched the data and
inp_valid can be deasserted. Likewise for output, assert out_ready when
ready to latch. On the first clock cycle both that and out_valid are asserted,
the module will assume the data has been latched externally.
For the input data, inp_bits_ptext should be the plaintext to encrypt and
inp_bits_tweak should be the tweak to use. For the output, out_bits_ctext is
the ciphertext. The plaintext and tweak used to generate it are provided as
out_bits_ptext and out_bits_tweak respectively.
This module has a four stage pipeline. Hence, it preserves the plaintext and tweak on the output for validation. It also assumes that the keys are never changed. If they are changed, any encryptions still "in flight" will give incorrect answers.