Oblivious Transfer from Weak Noisy Channels

Various results show that oblivious transfer can be implemented using the assumption of

noisy channels

. Unfortunately, this assumption is not as weak as one might think, because in a cryptographic setting, these noisy channels must satisfy very strong security requirements.

Unfair noisy channels

, introduced by Damgård, Kilian and Salvail [Eurocrypt ’99], reduce these limitations: They give the adversary an unfair advantage over the honest player, and therefore weaken the security requirements on the noisy channel. However, this model still has many shortcomings: For example, the adversary’s advantage is only allowed to have a very special form, and no error is allowed in the implementation.

In this paper we generalize the idea of unfair noisy channels. We introduce two new models of cryptographic noisy channels that we call the

weak erasure channel

and the

weak binary symmetric channel

, and show how they can be used to implement oblivious transfer. Our models are more general and use much weaker assumptions than unfair noisy channels, which makes implementation a more realistic prospect. For example, these are the first models that allow the parameters to come from experimental evidence.