@article{Chou_Kannwischer_Yang_2021, title={Rainbow on Cortex-M4}, volume={2021}, url={https://tches.iacr.org/index.php/TCHES/article/view/9078}, DOI={10.46586/tches.v2021.i4.650-675}, abstractNote={<p>We present the first Cortex-M4 implementation of the NISTPQC signature finalist Rainbow. We target the Giant Gecko EFM32GG11B which comes with 512 kB of RAM which can easily accommodate the keys of RainbowI.<br>We present fast constant-time bitsliced F<sub>16</sub> multiplication allowing multiplication of 32 field elements in 32 clock cycles. Additionally, we introduce a new way of computing the public map <em>P</em> in the verification procedure allowing vastly faster signature verification.<br>Both the signing and verification procedures of our implementation are by far the fastest among the NISTPQC signature finalists. Signing of rainbowIclassic requires roughly 957 000 clock cycles which is 4× faster than the state of the art Dilithium2 implementation and 45× faster than Falcon-512. Verification needs about 239 000 cycles which is 5× and 2× faster respectively. The cost of signing can be further decreased by 20% when storing the secret key in a bitsliced representation.</p>}, number={4}, journal={IACR Transactions on Cryptographic Hardware and Embedded Systems}, author={Chou, Tung and Kannwischer, Matthias J. and Yang, Bo-Yin}, year={2021}, month={Aug.}, pages={650–675} }