M. Garcia-Bosque

Application of a MEMS-Based TRNG in a Chaotic Stream Cipher

In this work, we used a sensor-based True Random Number Generator in order to generate keys for a stream cipher based on a recently published hybrid algorithm mixing Skew Tent Map and a Linear Feedback Shift Register. The stream cipher was implemented and tested in a Field Programmable Gate Array (FPGA) and was able to generate 8-bit width data streams at a clock frequency of 134 MHz, which is fast enough for Gigabit Ethernet applications. An exhaustive cryptanalysis was completed, allowing us to conclude that the system is secure. The stream cipher was compared with other chaotic stream ciphers implemented on similar platforms in terms of area, power consumption, and throughput.

Secure communication system based on a logistic map and a linear feedback shift register

In this paper we propose a fast and secure encryption system with a mixed-architecture based on a Modified Logistic Map and a Linear Feedback Shift Register. The system has been simulated showing that it can encrypt and decrypt images efficiently. The encrypted messages have been able to pass the NIST as well as the diehard battery of tests proving that the system is secure.

Continuous-time equalizer for CMOS integrated photodiodes

Fully integrated optoelectronic interfaces in CMOS technology are a very interesting option for optical smart sensors because they are a cost-effective and compact solution. However, CMOS standard n-well/p-bulk differential photodiodes (DPDs) are the bottleneck in this field due to their inherent limited bandwidth which falls below 10MHz in 65nm CMOS. This work presents a new equalization approach to enhance the bandwidth of CMOS integrated DPDs used in optical sensors. It is designed based on a split-path topology in which the gain and the boost are completely decoupled and can be externally adjusted by means of independent control voltages. This feature, particularly helpful for calibration, is not present in conventional equalizers based on the degenerated differential pair. The proposed equalization technique has been simulated in a 65nm process, where it has been able to increase the bandwidth of the DPD from their inherent 10MHz up to 3GHz with a single supply voltage of only 1.2V.

Lightweight ciphers based on chaotic Map - LFSR architectures

In this paper, we propose and analyze two different stream ciphers based on a Skew Tent Map and a Modified Logistic Map respectively. In order to improve the randomness of these systems, a single method for increasing the period length of the generated sequences has been applied. The results prove that the randomness of these systems can be severally increased by using this method, making these systems suitable for secure communications.

A new simple technique for improving the random properties of chaos-based cryptosystems

A new technique for improving the security of chaos-based stream ciphers has been proposed and tested experimentally. This technique manages to improve the randomness properties of the generated keystream by preventing the system to fall into short period cycles due to digitation. In order to test this technique, a stream cipher based on a Skew Tent Map algorithm has been implemented on a Virtex 7 FPGA. The randomness of the keystream generated by this system has been compared to the randomness of the keystream generated by the same system with the proposed randomness-enhancement technique. By subjecting both keystreams to the National Institute of Standards and Technology (NIST) tests, we have proved that our method can considerably improve the randomness of the generated keystreams. In order to incorporate our randomness-enhancement technique, only 41 extra slices have been needed, proving that, apart from effective, this method is also efficient in terms of area and hardware resources.

Fast and secure chaotic stream cipher with a MEMS-based seed generator

In this work, we have used a new concept of sensor-based seed generator in order to generate the keys for a stream cipher based on a new algorithm mixing a Skew Tent Map and a Linear Feedback Shift Register. The cryptosystem has been implemented in a Xilinx Virtex 7 FPGA and has been proven to be fast and secure for application in IoT networks.

Transimpedance amplifier with programmable gain and bandwidth for capacitive MEMS accelerometers

In this work, a capacitance-to-voltage converter based on a fully-differential transimpedance amplifier (TIA) with programmable gain and bandwidth for MEMS accelerometers is presented. It is aimed for a differential surface-micromachined comb-finger capacitive accelerometer, but can be used in many other capacitive sensor applications. The TIA has been designed in a 180-nm CMOS technology and it achieves a minimum equivalent input noise of 42 fA/√Hz at 50 kHz, which corresponds to an acceleration noise of 100 μg/√Hz.

A new multiple ciphering scheme for improving randomness

In this paper, we propose a new multiple ciphering scheme based on a Deficit Weighted Round Robin (DWRR) algorithm to improve the randomness results in the keystream generated by a stream cipher. This scheme has been implemented and tested in a Xilinx Virtex 7 FPGA. The randomness test results of the resulting keystream have proved that this scheme can be used to improve the quality of a stream cipher by increasing the resources used in its implementation a reasonable amount.