Severin Winkler

Publications (9) View all

• Article: On the Efficiency of Classical and Quantum Secure Function Evaluation

  Severin Winkler, Jürg Wullschleger
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  ABSTRACT: We provide bounds on the efficiency of secure one-sided output two-party computation of arbitrary finite functions from trusted distributed randomness in the statistical case. From these results we derive bounds on the efficiency of protocols that use different variants of OT as a black-box. When applied to implementations of OT, these bounds generalize most known results to the statistical case. Our results hold in particular for transformations between a finite number of primitives and for any error. In the second part we study the efficiency of quantum protocols implementing OT. While most classical lower bounds for perfectly secure reductions of OT to distributed randomness still hold in the quantum setting, we present a statistically secure protocol that violates these bounds by an arbitrarily large factor. We then prove a weaker lower bound that does hold in the statistical quantum setting and implies that even quantum protocols cannot extend OT. Finally, we present two lower bounds for reductions of OT to commitments and a protocol based on string commitments that is optimal with respect to both of these bounds.
  05/2012;
• Source

  Available from: Marco Tomamichel

  Article: Impossibility of growing quantum bit commitments.

  Severin Winkler, Marco Tomamichel, Stefan Hengl, Renato Renner
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  ABSTRACT: Quantum key distribution (QKD) is often, more correctly, called key growing. Given a short key as a seed, QKD enables two parties, connected by an insecure quantum channel, to generate a secret key of arbitrary length. Conversely, no key agreement is possible without access to an initial key. Here, we consider another fundamental cryptographic task, commitments. While, similar to key agreement, commitments cannot be realized from scratch, we ask whether they may be grown. That is, given the ability to commit to a fixed number of bits, is there a way to augment this to commitments to strings of arbitrary length? Using recently developed information-theoretic techniques, we answer this question in the negative.
  Physical Review Letters 08/2011; 107(9):090502. · 7.37 Impact Factor
• Article: Bit Commitment From Nonsignaling Correlations.

  Severin Winkler, Jürg Wullschleger, Stefan Wolf
  IEEE Transactions on Information Theory. 01/2011; 57:1770-1779.
• Source

  Available from: iacr.org

  Article: On the Efficiency of Bit Commitment Reductions.

  Samuel Ranellucci, Alain Tapp, Severin Winkler, Jürg Wullschleger
  IACR Cryptology ePrint Archive. 01/2011; 2011:324.
• Conference Proceeding: On the Efficiency of Bit Commitment Reductions.

  Samuel Ranellucci, Alain Tapp, Severin Winkler, Jürg Wullschleger
  Advances in Cryptology - ASIACRYPT 2011 - 17th International Conference on the Theory and Application of Cryptology and Information Security, Seoul, South Korea, December 4-8, 2011. Proceedings; 01/2011