Digital Secret Unknown Cipher (SUC) has been proposed in the last decade targeting to counteract the drawbacks of the traditional analog Physical Unclonable Functions (PUF). The SUCs, as pure-digital units, exhibit consistent operation during the whole digital unit's lifetime. This makes SUCs as PUF alternatives attractive for practical creation of clone-resistant units for a broad spectrum of applications especially in automotive and other mass-product cases. In this paper, we propose a novel SUC creation scenario as a random stream cipher to be embedded in Microsemi SmartFusion®2 System on Chip (SoC) FPGAs. The resulting cipher as a Key Stream Generators (KSG) is T-functions-based creating individual and randomized secret-key-streams which are individual for each unit. The proposed SUC-based Random Stream Cipher (RSC-SUC) is a lightweight SUC realization optimized for the SmartFusion®2 SoC FPGA technology. The security analysis and hardware complexity issues of the resulting RSC-SUC structures are also discussed and evaluated.

This work is targeting a solid security improvement in the wireless communication between existing and possibly future implantable medical devices (IMDs) and Programmer Monitor Device (PMD). A public medical server acting as a trusted Authority is introduced. A dedicated Pacemaker Proxy Device (PPD) is proposed to serve as a security mediator between PMD and IMD taking care of all medical security, liability and responsibility issues. The key idea is based on embedding low-complexity and resilient digital physical identities based on a new concept in the system devices to prohibit physical substitution/cloning attacks. A biometric identity extracted from the patient's ECG (electrocardiogram) is supporting the security system by adding rather hard-to-clone patient personal health profile. A machine learning algorithm is deployed to extract such biometric identity (key). The initial results of the proposed approach showed practical accuracy in extracting the biometric identity approaching 95%. The whole resulting system ensures solid, resilient and high level of protection for future smart medical environment.

Electronic Cash (EC) is still suffering from being difficult to transfer values as a digital stream on open channels. The fact that a value stream of bits is often traceable, anonymity and protection against double-spending becomes a very difficult task. In physical cash, coins and bills are exchanged physically persons resulting with assured transport of value by the fact that the physical transfer of money assures no possibility for duplication. Block-chaining technique in Bitcoin attempts to prohibit doubling by majority observation with also a limited success in anonymity and double spending issues. We introduce a new concept for E-Coin circulations by prohibiting the knowledge of the coins to any exchanging party. The only one who knows the coins is the minting authority considered as a trusted authority. The coins are made only possible to identify without being able to see them in critical exchange phases by the exchanging parties, thus prohibiting doubling of coins. The key idea of the new concept is to store the coins in unclonable physical Electronic-Wallets (UEW). The coins can be provably transferred without being seen by users. The UEWs can only be used to verify, accommodate and exchange coins only between wallets under the sole control of the users. Users and manufacturers and even Trusted Authorities TAs have no possibilities to clone UEW and duplicate E-coins. The concept is both bio-inspired regarding unclonable entities and physical-cash-inspired as only the minting banks can duplicate coins and bills. The new E-Coin concept is based on using Physically Unclonable Functions (PUFs) in a new form as digital Secret Unknown Cipher (SUC).

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.

Many automotive Remote Keyless Entry (RKE) systems have been successfully attacked in the last few years. The security of RKE systems is still a sensitive and crucial issue for vehicular industry. The problem needs to be essentially addressed by the fundamental fabrication weakness namely: "the manufacture can clone his own fabricated keys" and create equal units. This should not be possible. The fact that: "the only safe secret is the one which nobody knows" leads to proposing the fabrication of physically "Secret Unknown Cipher" (SUC) to serve as a clone-resistant security anchor (module) for the RKE system. Each fabricated key, in its ultimate case, is then equivalent to an individual unclonable DNA-like biological entity. We preset a protocol exhibiting mutual authentication properties to manage a complete RKE system. It is based on a digital hardware token incorporating an SUC module designed to fit to the vehicular industrial mass-production environment at reasonable costs.

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.