A concept for creating a large class of lightweight stream ciphers as Key Stream Generators KSGs is presented. The resulting class-size exceeds 2³²³ possible different KSGs. If one unknown cipher from the KSG-class is randomly picked-up and stored irreversibly within a VLSI device, the device becomes physically hard-to-clone. The selected cipher is only usable by the device itself, therefore cloning it requires an invasive attack on that particular device. Being an unknown selection out of 2³²³ possible KSGs, the resulting cipher is seen as a Secret Unknown Cipher (SUC). The SUC concept was presented a decade ago as a digital alternative to the inconsistent traditional analog Physically Unclonable Functions (PUFs). This work presents one possible practical self-creation technique for such PUFs as hard-to-clone unknown KSGs usable to re-identify VLSI devices. The proposed sample cipher-structure is based on non-linear merging of randomly selected 16 Nonlinear Feedback Shift Registers (NLFSRs). The created KSGs exhibit linear complexities exceeding 2⁸¹ and a period exceeding 2¹⁶¹. The worst-case device cloning time complexity approaches 2¹⁶². A simple lightweight identification protocol for physically identifying such SUC structures in FPGA-devices is presented. The required self-reconfiguring FPGAs for embedding such SUCs are not yet available, however, expected to emerge in the near future. The security analysis and hardware complexities of the resulting clone-resistant structures are evaluated and shown to offer scalable security levels to cope even with the post-quantum cryptography.

Fleet Management (FM) deals with the management of transport, distribution, and logistics of national and international goods exchange, in which many operators worldwide are involved. Fleet management involves many security-relevant participating entities, such as vehicles, FM mobile clients, smart trackers with goods, drivers, etc. Existing automated fleet management systems are basically vulnerable to physical replacement attacks when managed by mass-produced electronic identities. Analog Physical Unclonable Functions (PUFs) failed to serve as unclonable electronic identities due to being costly, unstable and inefficient for such mass-usage. We propose in this paper to deploy the Secret Unknown Ciphers (SUCs) techniques introduced a decade ago as digital low-cost clone-resistant identities to be embedded in selected participating electronic Fleet Management System (FMS) units. SUCs, as stable self-created digital modules to be embedded in future smart non-volatile (NV)-FPGA devices, are expected to cover all emerging FMS physical security requirements. Such information-retaining units (when switched-off) are emerging to become widely used as ultra-low-power mass-products in automotive environment. We propose a new FMS security architecture based on embedding SUC modules in each security-relevant entity in the FMS such as vehicles, mobile clients, smart trackers and goods. This paper investigates the expected technical impacts when using SUCs technology as physical security anchors in a standard FMS configuration. Several SUC-related generic security protocols adapted to the FM environment show how to securely-link tracing of goods, tracks routing, and personnel in such FM system. It is also shown how to combine other biometric fingerprints to simplify personal liability and enhance the security management in such globally-operating automated procedures. The presented security analysis of the resulting FMS shows that the major security concerns in existing FMSs can be resolved. One major advantage of SUC technique, is that device-manufacturers can be largely-excluded as security players. The FPGA technology required for the SUC solution is currently not available and is thought for future use. The concept is ultimately applicable if the future electronic mass products would deploy self-reconfiguring non-volatile (flash-based) System on Chip smart units. Such units are expected to dominate future Internet of Things (IoT) ultra-low-energy applications, as power-off does not lose any information. The proposed SUC strategy is highly flexible, scalable, and applicable to cover a large class of globally operating protection mechanisms similar to those of the addressed FMS scenarios.

The Secret Unknown Cipher (SUC) concept was introduced a decade ago as a promising technique for creating pure digital clone-resistant electronic units as alternatives to the traditional non-consistent Physical Unclonable Functions (PUFs). In this work, a very special unconventional cipher design is presented. The design uses hard-core FPGA (Field Programmable Gate Arrays) -Mathblocks available in modern system-on-chip (SoC) FPGAs. Such Mathblocks are often not completely used in many FPGA applications; therefore, it seems wise to make use of such dead (unused) modules to fabricate usable physical security functions for free. Standard cipher designs usually avoid deploying multipliers in the cipher mapping functions due to their high complexity. The main target of this work is to design large cipher classes (e.g., cipher class size >2⁶⁰⁰) by mainly deploying the FPGA specific mathematical cores. The proposed cipher designs are novel hardware-oriented and new in the public literature, using fully new unusual mapping functions. If a random unknown selection of one cipher out of 2⁶⁰⁰ ciphers is self-configured in a device, then a Secret Unknown Cipher module is created within a device, making it physically hard to clone. We consider the cipher module for free (for zero cost) if the major elements in the cipher module are making use of unused reanimated Mathblocks. Such ciphers are usable in many future mass products for protecting vehicular units against cloning and modeling attacks. The required self-reconfigurable devices for that concept are not available now; however, they are expected to emerge in the near future.

Telemedicine applications are more and more used due to the rapid development of digital imaging and information and communication technologies. Medical information which include digital medical images and patient’s information are extracted and transmitted over insecure networks for clinical diagnosis and treatments. Digital watermarking is one of the main approaches used to ensure the security of medical images. Nevertheless, in some cases, the only use of digital watermarking is not sufficient to reach a high level of security. Indeed, the watermark could carry essential patient information and needs to be protected. In such cases, cryptography may be used to protect the watermark and to improve the overall secured management in the medical environment. In this paper, we propose a clone-resistant watermarking approach combining a difference expansion watermarking technique with a cryptographic technique based on secret keys generated by a clone-resistant device called Secret Unknown Ciphers (SUCs). The use of SUCs to sign the watermark enforces the security of medical images during their transfer and storage. Experimental results show that the system provides a high level of security against various forms of attacks.

New large classes of permutations over ${\mathbb{Z}}_{2^n}$ based on T-Functions as Self-Inverting Permutation Functions (SIPFs) are presented. The presented classes exhibit negligible or low complexity when implemented in emerging FPGA technologies. The target use of such functions is in creating the so called Secret Unknown Ciphers (SUC) to serve as resilient Clone-Resistant structures in smart non-volatile Field Programmable Gate Arrays (FPGA) devices. SUCs concepts were proposed a decade ago as digital consistent alternatives to the conventional analog inconsistent Physical Unclonable Functions PUFs. The proposed permutation classes are designed and optimized particularly to use non-consumed Mathblock cores in programmable System-on-Chip (SoC) FPGA devices. Hardware and software complexities for realizing such structures are optimized and evaluated for a sample expected target FPGA technology. The attained security levels of the resulting SUCs are evaluated and shown to be scalable and usable even for post-quantum crypto systems.

The contemporary e-commerce is still missing a widely available and acceptable electronic cash (e-cash) system for the masses. This problem is due to the conflict of interests between banks, governments and community. In this paper we first describe the problems faced by past e-cash systems. Then we focus on the so-called success factors, which are essentially required for a highly accepted e-cash system. Based on these success factors, we will present a new system called fairCASH. fairCASH is a multi-purpose, multihop, pre-paid and anonymous electronic payment system. It makes use of a secured chip (CASTOR), which is completely under user's control. The chip uses a new identification technology called Electronic Identity Mutation (EIM) to fabricate uniquely electronic identities.