Memory deduplication shares same-content memory pages and reduces the consumption of physical memory. It is effective on environments that run many virtual machines with the same operating system. Memory deduplication, however, is vulnerable to memory disclosure attacks, which reveal the existence of an application or file on another virtual machine. Such an attack takes advantage of a difference in write access times on deduplicated memory pages that are recreated by Copy-On-Write. In our experience on KSM (kernel samepage merging) with the KVM virtual machine, the attack could detect the existence of sshd and apache2 on Linux, and IE6 and Firefox on WindowsXP. It also could detect a downloaded file on the Firefox browser. We describe the attack mechanism in this paper, and also mention countermeasures against this attack.

Determining whether two or more packages cannot be installed together is an important issue in the quality assurance process of package-based distributions. Unfortunately, the sheer number of different configurations to test makes this task particularly challenging, and hundreds of such incompatibilities go undetected by the normal testing and distribution process until they are later reported by a user as bugs that we call "conflict defects". We performed an extensive case study of conflict defects extracted from the bug tracking systems of Debian and Red Hat. According to our results, conflict defects can be grouped into five main categories. We show that with more detailed package meta-data, about 30 % of all conflict defects could be prevented relatively easily, while another 30 % could be found by targeted testing of packages that share common resources or characteristics. These results allow us to make precise suggestions on how to prevent and detect conflict defects in the future.

All cryptography systems have a True Random Number Generator (TRNG). In the process of validating, these systems are necessary for prototyping in Field Programmable Gate Array (FPGA). However, TRNG uses an entropy source based on non-deterministic effects challenging to replicate in FPGA. This work shows the problems and solutions to implement an entropy source based on frequency collapse in multimodal Ring Oscillators (RO). The entropy source implemented in FPGA pass all SP800-90B tests from the National Institute of Standards and Technology (NIST) with a good entropy compared to related works. The TRNG passes all NIST SP800-22 with and without the post-processing stage. Besides, the TRNG and the post-processing stage pass all tests of Application notes and Interpretation of the Scheme (AIS31). The TRNG implementation on a Xilinx Artix-7 XC7A100TCSG324 FPGA occupies less than 1% of the resources. This work presents 0.62 µs up to 9.92 µs of sampling latency and 1.1 Mbps up to 9.1 Mbps of bit rate throughput.INDEX TERMS TRNG, NIST, AIS31, Frequency collapse.

Fully depleted silicon-on-insulator (FD-SOI) technology is renowned for its back-gate bias voltage controllability. It allows devices fabricated with FD-SOI technology to be optimized for low power consumption or high performance with proper back-gate biases, depending on the required application. This article proposes using the back-gate biasing technique in novel countermeasures against power analysis attacks. Theoretical explanations are discussed, and realistic differential power analysis (DPA) attacks, targeting AES-128 encryption on a 65-nm STOB 32-bit RISC-V microcontroller, are conducted to justify the proposed idea. The experimental results show that when compared with applying no bias, applying our first proposal, which involves using forward back-gate bias, not only improves the test device performance but also enhances its resistance to DPA attacks. Moreover, vulnerability to DPA attacks is kept unchanged when a reverse back-gate bias is applied to achieve low power consumption. The DPA resistance is even more vital when combining the back-gate bias technique with a lower supply voltage. The number of power traces required to retrieve the secret key successfully increases by 14.5 times in the best case. Even better DPA resistance can be obtained when the back-gate bias of the targeted microcontroller is dynamically randomized, as suggested by our second proposal of a random dynamic back-gate bias (RDBB). When RDBB is applied, the number of power traces required to retrieve the secret key successfully significantly increases by 33.4 times. INDEX TERMS Side-channel attacks, differential power analysis, countermeasure, back-gate biasing, FD-SOI, SOTB, RISC-V.

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