  We present a scalable "Trustworthy Container Repository" (TCR) infrastructure
for the storage of software container images, such as those used by Docker.
Using an authenticated data structure based on index-ordered Merkle trees
(IOMTs), TCR aims to provide assurances of 1) Integrity, 2) Availability, and
3) Confidentiality to its users, whose containers are stored in an untrusted
environment. Trust within the TCR architecture is rooted in a low-complexity,
tamper-resistant trusted module. The use of IOMTs allows such a module to
efficiently track a virtually unlimited number of container images, and thus
provide the desired assurances for the system's users. Using a simulated
version of the proposed system, we demonstrate the scalability of platform by
showing logarithmic time complexity up to $2^{25}$ (32 million) container
images. This paper presents both algorithmic and proof-of-concept software
implementations of the proposed TCR infrastructure.

Cryptography and Security