Porting the Embedded Xinu Operating System to the Raspberry Pi

This thesis presents a port of a lightweight instructional operating system called Embedded Xinu to the Raspberry Pi. The Raspberry Pi, an inexpensive credit-card-sized computer, has attracted a large community of hobbyists, researchers, and educators since its release in 2012. However, the system-level software running on the Raspberry Pi has been restricted to two ends of a spectrum: complex modern operating systems such as Linux at one end, and very simple hobbyist operating systems or simple “bare-metal” programs at the other end. This project bridges this gap by porting the Embedded Xinu operating system to the Raspberry Pi. Although simple and designed for educational use, Embedded Xinu supports major features of modern operating systems such as preemptive multitasking and networking. This thesis also presents the addition of new optional features, such as USB support, to Embedded Xinu, and demonstrates major challenges that may arise when writing device drivers for modern hardware

Adiantum: length-preserving encryption for entry-level processors

We present HBSH, a simple construction for tweakable length-preserving encryption which supports the fastest options for hashing and stream encryption for processors without AES or other crypto instructions, with a provable quadratic advantage bound. Our composition Adiantum uses NH, Poly1305, XChaCha12, and a single AES invocation. On an ARM Cortex-A7 processor, Adiantum decrypts 4096-byte messages at 10.6 cycles per byte, over five times faster than AES-256-XTS, with a constant-time implementation. We also define HPolyC which is simpler and has excellent key agility at 13.6 cycles per byte

Length-preserving encryption with HCTR2

On modern processors HCTR is one of the most efficient constructions for building a tweakable super-pseudorandom permutation. However, a bug in the specification and another in Chakraborty and Nandi\u27s security proof invalidate the claimed security bound. We here present HCTR2, which fixes these issues and improves the security bound, performance and flexibility. GitHub: https://github.com/google/hctr

PROCESSING AND DELIVERING SECURITY SIGNALS FROM GUESTS TO HOSTS IN VIRTUALIZED ENVIRONMENTS

This disclosure describes techniques that leverage memory organization in virtual machines and their hosts to emplace code that protects against malware. Malware detection instrumentation is emplaced in guest kernel space, which is relatively privileged and better protected than other guest memory spaces. Malware behavioral analysis logic, which classifies a guest process as benign or malign, is emplaced in host ring 3 space, to take advantage of the virtualization boundary. Even if unaffected by the attack, the protected kernel may still not be able to quickly communicate knowledge of the attack to the malware behavioral analysis logic, which resides in the host. This is because such communication normally travels through guest userspace, which may be compromised. This disclosure further describes techniques that enable the guest kernel to communicate sensitive information to the host while bypassing guest userspace, e.g., by using a virtio-vsock channel

Adiantum: length-preserving encryption for entry-level processors

We present HBSH, a simple construction for tweakable length-preserving encryption which supports the fastest options for hashing and stream encryption for processors without AES or other crypto instructions, with a provable quadratic advantage bound. Our composition Adiantum uses NH, Poly1305, XChaCha12, and a single AES invocation. On an ARM Cortex-A7 processor, Adiantum decrypts 4096-byte messages at 10.6 cycles per byte, over five times faster than AES-256-XTS, with a constant-time implementation. We also define HPolyC which is simpler and has excellent key agility at 13.6 cycles per byte

The pineapple genome and the evolution of CAM photosynthesis

International audiencePineapple (Ananas comosus (L.) Merr.) is the most economically valuable crop possessing crassulacean acid metabolism (CAM), a photosynthetic carbon assimilation pathway with high water-use efficiency, and the second most important tropical fruit. We sequenced the genomes of pineapple varieties F153 and MD2 and a wild pineapple relative, Ananas bracteatus accession CB5. The pineapple genome has one fewer ancient whole-genome duplication event than sequenced grass genomes and a conserved karyotype with seven chromosomes from before the duplication event. The pineapple lineage has transitioned from C3 photosynthesis to CAM, with CAM-related genes exhibiting a diel expression pattern in photosynthetic tissues. CAM pathway genes were enriched with cis-regulatory elements associated with the regulation of circadian clock genes, providing the first cis-regulatory link between CAM and circadian clock regulation. Pineapple CAM photosynthesis evolved by the reconfiguration of pathways in C3 plants, through the regulatory neofunctionalization of preexisting genes and not through the acquisition of neofunctionalized genes via whole-genome or tandem gene duplicatio