Publications

Under the Navy's Flexible Cyber-Secure Radio (FlexCSR) program, the Naval Information Warfare Center Pacific and the Massachusetts Institute of Technology's Lincoln Laboratory are jointly developing a unique cybersecurity solution for tactical unmanned systems (UxS): the FlexCSR Security/Cyber Module (SCM) End Cryptographic Unit (ECU). To deal with possible loss of unmanned systems that contain the device, the SCM ECU uses only publicly available Commercial National Security Algorithms and a Tactical Key Management system to generate and distribute onboard mission keys that are destroyed at mission completion or upon compromise. This also significantly reduces the logistic complexity traditionally involved with protection and loading of classified cryptographic keys. The SCM ECU is on track to be certified by the National Security Agency for protecting tactical data-in-transit up to Secret level. The FlexCSR SCM ECU is the first stand-alone cryptographic module that conforms to the United States Department of Defense (DoD) Joint Communications Architecture for Unmanned Systems, an initiative by the Office of the Secretary of Defense supporting the interoperability pillar of the DoD Unmanned Systems Integrated Roadmap. It is a credit card-sized enclosed unit that provides USB interfaces for plaintext and ciphertext, support for radio controls and management, and a software Application Programming Interface that together allow easy integration into tactical UxS communication systems. This paper gives an overview of the architecture, interfaces, usage, and development and approval schedule of the device.

As the rate at which digital data is generated continues to grow, so does the need to ensure that data can be stored securely. The use of an NSA-certified Inline Media Encryptor (IME) is often required to protect classified data, as its security properties can be fully analyzed and certified with minimal coupling to the environment in which it is embedded. However, these devices are historically purpose-built and must often be redesigned and recertified for each target system. This tedious and costly (but necessary) process limits the ability for an information system architect to leverage advances made in storage technology. Our universal Classified Data At Rest (CDAR) architecture represents a modular approach to reduce this burden and maximize interface flexibility. The core module is designed around NVMe, a high-performance storage interface built directly on PCIe. Interfacing with non-NVMe interfaces such as SATA is achieved with adapters which are outside the certification boundary and therefore can be less costly and leverage rapidly evolving commercial technology. This work includes an analysis for both the functionality and security of this architecture. A prototype was developed with peak throughput of 23.9 Gb/s at a power consumption of 8.5W, making it suitable for a wide range of storage applications.

Attribute-based encryption (ABE) enables encryption of messages under access policies so that only users with attributes satisfying the policy can decrypt the ciphertext. In standard ABE, an arbitrary number of colluding users, each without an authorized attribute set, cannot decrypt the ciphertext. However, all existing ABE schemes rely on concrete cryptographic assumptions such as the hardness of certain problems over bilinear maps or integer lattices. Furthermore, it is known that ABE cannot be constructed from generic assumptions such as public-key encryption using black-box techniques. In this work, we revisit the problem of constructing ABE that tolerates collusions of arbitrary but a priori bounded size. We present two ABE schemes secure against bounded collusions that require only semantically secure public-key encryption. Our schemes achieve significant improvement in the size of the public parameters, secret keys, and ciphertexts over the previous construction of bounded-collusion ABE from minimal assumptions by Gorbunov et al. (CRYPTO 2012). In fact, in our second scheme, the size of ABE secret keys does not grow at all with the collusion bound. As a building block, we introduce a multidimensional secret-sharing scheme that may be of independent interest. We also obtain bounded-collusion symmetric-key ABE (which requires the secret key for encryption) by replacing the public-key encryption with symmetric-key encryption, which can be built from the minimal assumption of one-way functions.