OleF: an Inverse-Free Online Cipher. An Online SPRP with an Optimal Inverse-Free Construction

@article{Bhaumik2016OleFAI,
  title={OleF: an Inverse-Free Online Cipher. An Online SPRP with an Optimal Inverse-Free Construction},
  author={Ritam Bhaumik and Mridul Nandi},
  journal={IACR Trans. Symmetric Cryptol.},
  year={2016},
  volume={2016},
  pages={30-51}
}
Online ciphers, in spite of being insecure against an sprp adversary, can be desirable at places because of their ease of implementation and speed. Here we propose a single-keyed inverse-free construction that achieves online sprp security with an optimal number of blockcipher calls. We also include a partial block construction, without requiring any extra key.