We show how to QOTP-encrypt classical plaintext in a nontrivial way: we encode a plaintext bit as the vector $\pm(1,1,1)/\sqrt3$ on the Bloch sphere. Applying the Pauli encryption operators results in eight possible cipherstates which are equally spread out on the Bloch sphere. This encoding, especially when combined with the half-keylength option of QOTP, has advantages over 4-state and 6-state encoding in applications such as Quantum Key Recycling and Unclonable Encryption. We propose a key recycling scheme that is more efficient and can tolerate more noise than a recent scheme by Fehr and Salvail.
For 8-state QOTP encryption with pseudorandom keys we do a statistical analysis of the cipherstate eigenvalues. We present numerics up to 9 qubits.Category / Keywords: quantum cryptography Date: received 28 Nov 2016, last revised 28 Dec 2016 Contact author: b skoric at tue nl Available format(s): PDF | BibTeX Citation Note: Improved the Key Recycling scheme. Extended the results on key length. Version: 20161229:064733 (All versions of this report) Short URL: ia.cr/2016/1122 Discussion forum: Show discussion | Start new discussion