Deep learning, when integrated with a large amount of training data, has the
potential to outperform machine learning in terms of high accuracy. Recently,
privacy-preserving deep learning has drawn significant attention of the
research community. Different privacy notions in deep learning include privacy
of data provided by data-owners and privacy of parameters and/or
hyperparameters of the underlying neural network. Federated learning is a
popular privacy-preserving execution environment where data-owners participate
in learning the parameters collectively without leaking their respective data
to other participants. However, federated learning suffers from certain
security/privacy issues. In this paper, we propose Split-n-Chain, a variant of
split learning where the layers of the network are split among several
distributed nodes. Split-n-Chain achieves several privacy properties:
data-owners need not share their training data with other nodes, and no nodes
have access to the parameters and hyperparameters of the neural network (except
that of the respective layers they hold). Moreover, Split-n-Chain uses
blockchain to audit the computation done by different nodes. Our experimental
results show that: Split-n-Chain is efficient, in terms of time required to
execute different phases, and the training loss trend is similar to that for
the same neural network when implemented in a monolithic fashion.