Usuba

Usuba is a programming language to write bitsliced code. It compiles optimized to C code (+ intrinsics).

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Presentation

Go to our website to find more about Usuba.

In particular, the following blog articles are a good introduction:

• Usuba - The Genesis explains the motivation behind Usuba.

• Bitslicing presents the bitslicing technique, which is the basis of Usuba.

To go into more details, read our published papers about Usuba:

• Darius Mercadier, Pierre-Evariste Dagand. Usuba: High-Throughput and Constant-Time Ciphers, by Construction, PLDI 2019.

• Darius Mercadier, Pierre-Évariste Dagand, Lionel Lacassagne, Gilles Muller, Usuba, Optimizing & Trustworthy Bitslicing Compiler, WPMVP 2018.

Finally, some additional resources that could be useful:

• Timeless: One-page presentation of Usuba

• June 2019: Technical presentation of Usuba @PLDI'19

• February 2019: High-level presentation of Usuba @Inria's Junior Seminar

Installation

Usuba is written in OCaml. On a Debian system, you should be able to setup the base environment with

./install_deps.sh

You can then compile Usuba with:

./configure.pl
make

A few examples

A few examples of Usuba codes:

• bitslice DES (and the generated C code),
• bitslice AES (and the generated C code),
• n-slice AES (and the generated C code),
• 32-slice Serpent (and the generated C code),
• 32-slice Chacha20 (and the generated C code).

If you are familiar with Perl, an easy way to see the compiler an action is to look at the scripts in the directory checks/correctness that compile a few Usuba codes, run them and make sure they produce the expected results.

Compiling

To compile an Usuba file (.ua), you need to invoke ./usubac <options> <source.ua> (the Usuba source file must be the last argument). I strongly recommand always using the flag -no-sched when doing pure bitslicing (it disables a few experimental options, and reduces the amount of code loaded). The option -no-arr-entry might also be usefull for small functions (combined with -no-arr). The list of flags can be obtained by running ./usubac -help.

For instance, to compile a bitslice AES:

./usubac -B -o aes.c -no-sched samples/usuba/aes.c

The C code generated by Usuba uses macros to achieve genericity. This macros are loaded with the instruction #include "XXX.h" at the begining of the C files generated, where XXX is one of STD, SSE, AVX (which should be AVX2), AVX512, Neon, AltiVec. Those headers are located in the directory arch.