Introduced by Halevi, Ishai, Kushilevitz, and Rabin (CRYPTO 2023), Additive randomized encodings (ARE) reduce the computation of a k-party function \(f(x_1,\dots ,x_k)\) to locally computing encodings \(\hat{x}_i\) of each input \(x_i\) and then adding them together over some Abelian group into an output encoding \(\hat{y} = \sum \hat{x}_i\) , which reveals nothing but the result. The appeal of ARE comes from the simplicity of the non-local computation, involving only addition. This gives rise for instance to non-interactive secure function evaluation in the shuffle model where messages from different parties are anonymously shuffled before reaching their destination. Halevi, Ishai, Kushilevitz, and Rabin constructed ARE based on Diffie-Hellman type assumptions in bilinear groups. We construct ARE assuming public-key encryption. The key insight behind our construction is that one-sided ARE, which only guarantees privacy for one of the parties, are relatively easy to construct, and yet can be lifted to full-fledged ARE. We also give a more efficient black-box construction from the CDH assumption.

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Additive Randomized Encodings from Public Key Encryption

  • Nir Bitansky,
  • Saroja Erabelli,
  • Rachit Garg

摘要

Introduced by Halevi, Ishai, Kushilevitz, and Rabin (CRYPTO 2023), Additive randomized encodings (ARE) reduce the computation of a k-party function \(f(x_1,\dots ,x_k)\) to locally computing encodings \(\hat{x}_i\) of each input \(x_i\) and then adding them together over some Abelian group into an output encoding \(\hat{y} = \sum \hat{x}_i\) , which reveals nothing but the result. The appeal of ARE comes from the simplicity of the non-local computation, involving only addition. This gives rise for instance to non-interactive secure function evaluation in the shuffle model where messages from different parties are anonymously shuffled before reaching their destination. Halevi, Ishai, Kushilevitz, and Rabin constructed ARE based on Diffie-Hellman type assumptions in bilinear groups. We construct ARE assuming public-key encryption. The key insight behind our construction is that one-sided ARE, which only guarantees privacy for one of the parties, are relatively easy to construct, and yet can be lifted to full-fledged ARE. We also give a more efficient black-box construction from the CDH assumption.