Echo on a Chip - Secure Embedded Systems in Cryptography

A New Perception for the Next Generation of Micro-Controllers handling Encryption for Mobile Messaging

Mancy A. Wake, Dorothy Hibernack, Lucas Lullaby

• Publisher: Books on Demand
• Year: 2020
• ISBN:
  9783751926874
• Edition: 1
• Topic: Computer Science
• Subtopic: Hardware
• Index: Computer Science

Based on the historical development of so-called Crypto Chips, the current Transformation of Cryptography shows numerous changes, innovations and new process designs in the field of Cryptography, which also need to be integrated in a hardware design of Microprocessors and Microcontrollers for a Secure Embedded System.Using the example of the encrypting Echo protocol, a design of a hardware architecture based on three Chips is presented: The central Echo Chip #1 represents a "Trusted Execution Environment" (TEE), which is not connected to the Internet for the conversion processes from plain text to cipher text and is supposed to remain quasi original, to prevent software injections or possible uploads of copies of the plain text. The technical specifications of all three microprocessors are described in detail.The established paradigm of separation is recognized as a security feature and discussed as a perception for a Next Generation of Microcontrollers in the field of Mobile Messaging under the technical term "Going the Extra Mile". This security architecture is then discussed in the context of seven different current risk cases with the consolidated result that the well-known OSI (Open Systems Interconnection) Model is expanded to the Secure Architecture Model, abbreviated SAM.

1 Historic development of Cryptographic Chips: From Enigma to Ecolex and AroFlex

In the past, cryptographic micro-controllers had primarily these functions since their first development in the mid-1970s (e.g. by Philips Usfa Crypto) - roughly in line with the spread of asymmetric encryption of a public key infrastructure (PKI):

• to carry out the encryption with the aid of a computer with a dedicated computing machine
• to offer the process to dedicated customers such as military or individual governments
• to convert ciphertext faster or more adapted to possibly more complex algorithms of the respective era
• respective to relate it in particular to the encryption of speech
• or to operate different channels in parallel –
• and above all: to include an uninfluenced, hardware-supported number generator.

Previously, the development of the Crypto-Chips was based on symmetrical encryption, just as Philips started with a one-time tape (OTT) called ECOLEX in 1956 (Philips Usfa 1982).

The Crypto-Chips digitized the previously mechanical encryption processes in an electronic processor, e.g. of the Enigma machines that have been developed by Chiffriermaschinen AG since the mid-1920s.

In the architectures, several chips were often chained one after the other in order to map cryptographic routines, for example to implement a stream cipher: Eight such chips were e.g. connected in the AroFlex machine. They were also called "crypto hearts" (Kraan 1986).

Likewise, a lot has been technically adapted over the years to make the chips more contemporary in their hardware, for example in the case of the transistors, or to adapt them to the general chip development. Today, single-board computers such as Raspberry Pi or Arduino and others are available and programmable for everyone.

The security of the uses of these “embedded systems” remains to be assessed and designed according to modern processes and standards of cryptography.

Other crypto machines that also used microprocessors, such as those from Crypto AG, were manipulated.

The Secret Service Coup of the Century first went public in 2020: The CIA and the German BND had bought the Swiss Crypto AG in 1970 under cover behind trustees. The hardware produced had been manipulated in order to be able to intercept governments from more than 100 countries that were customers of Crypto AG (Miller et al. 2020).

Hence, the development of secure embedded systems remains a hot topic for cryptography in the face of these disclosed historical developments.

2 Transformation of Cryptography influences Secure Embedded Systems in a Network

The more recent developments in cryptography in the 21st century are not only one-sided towards future quantum cryptography (PQCrypto 2019, Zimmermann 2019), but are already showing today fundamental changes in numerous existing processes:

It starts with multi-encryption, goes via Instant Perfect Forward Secrecy (IPFS) with end-to-end encryption with Cryptographic Calling, the adaptation of cryptographic protocols as through Fiasco Forwarding, in which up to a dozen keys out of a pool are used to decode a message.

It continues to solve the key transport problem with Secret Streams and Juggerknaut keys to a volatile and Exponential Encryption.

In their book "Transformation of Cryptography", the authors Linda Bertram and Gunther van Dooble (2019) have, for example, compiled over two dozen of these changes and innovative concepts that are currently influencing cryptography and whose transformation characterizes them: One can currently speak of a “Transformation of Cryptography”.

The transformation is therefore not just about the step into cryptography that is resistant to the fast computing operations of quantum computers, for example by exchanging the RSA algorithm with algorithms such as NTRU or McEliece (ibid 1978), but also about numerous development steps, which are emerging in multiple, also process-oriented ways, such as multi-encryption and new Internet protocols such as the Echo protocol (Gasakis / Schmidt 2018), which combines multi-encryption with aspects of graph theory.

Why shouldn't the newer cryptographic innovations also be included in the design of hardware, micro-controllers and embedded systems with their integrated and increasingly cryptographic processes?

Thanks to fast computing power, the cryptographic “chips” are faster than ever and also more mobile than ever.

With the smartphones, we hold small computers in our hands or in our pockets, which used to encompass several kilos or entire cupboards.

It is no longer just about becoming faster, smaller, more mobile, more trustworthy and more secure, but the software and hardware processes of a modern crypto-chip architecture are also to be adapted to the new requirements in accordance with the current Transformation of Cryptography.

Transferred to the hardware of Crypto-Chips and such secure embedded systems, the following potentials and questions can arise within this background:

• How can "Hearts" – Crypto-Chips – be linked with one another, also mobile and / or remotely, or at least communicate securely?

If micro-processors are not just single (multiple) hearts within a single algorithm, Crypto-Chips can also be seen as independent entities and organisms within a network that connect like individual satellites of a peer-to-peer network, and are organized according to a division of labor with swarm intelligence? Or form a network that only transfers encrypted packets via the TCP / IP protocol?

• Will we soon have Crypto-Chips that can form a mesh or map defined routes in the sense of graph theory?
• How can hardware machines then automatically create and manage new neighbors and their encryption keys?
• Different Crypto-Chips could refer to different algorithms: e.g. if multi-encryption of ciphertext of one algorithm is repeated with another, different algorithm?
• Why shouldn't a Crypto-Chip take on the task of a packet check as we know it from a router or deep packet inspection (König 2013), filtering out duplicates and double packets, checking signatures or cryptographic tokens or the hash values provided?
• Or why shouldn't another chip dedicated as a Trusted Execution Environment take over the encryption and decryption processes (conversion) without the plaintext having to go through further layers at the application, keyboard driver or operating system level?

Driven by increasing digitization and the growing number of devices in the Internet of Things (IoT), we are currently experiencing great demand for such secure hardware-based solutions for machine to machine (M2M) authentication, cryptography and data typing, data protection, data forwarding and data storage.

The change in cryptography as well as the demand of the market, especially for example in the networking of technical household appliances, places the topic of secure embedded systems in the central focus of modern research and teaching.

The German Central Association for the Electrical and Electronics Industries (ZVEI - Zentralverband Elektrotechnik und Elektronikindustrie) even created a "National Roadmap Embedded Systems" (2016), of which the first and priority strategy is "seamless interaction", which would be unthinkable today without cryptography in the area of secure embedded systems.

Thomas Wollinger et. al. already predicted at the “Embedded World - Exhibition and Conference” in 2003: “Thus, it is our view that designing and implementing efficient cryptographic algorithms on embedded systems will continue to be an active research area.”

Around 20 years later, with the Internet of Things, the fact that chips communicate with chips securely - washing machine to tablet like Alexa Echo-Dot to Alexa Echo-Dot - is virtually pandemic.

A publication by the IEEE by Pádraig Flood and Michael Schukat estimated "50 billion Internet-enabled devices" for 2020. A new Business Insider Intelligence study predicts even that the IoT market will grow 2025 to “more than 64 billion IoT devices” (Newman 2019).

We therefore see the explanations summarized in this essay, the references to the current Transformation of Cryptography, and the design draft to relate the referenced Echo protocol to the architecture and processes of a micro-controller as a basic element in the training of developers of microprocessors and in the teaching of the basics of cryptography and the security of embedded systems.

The further development of Crypto-Chips has been going on for many decades; however, it is currently facing new challenges that arise from the Transformation of Cryptography and the (secure) connection of hardware chips to hardware chips in a secure network.

In the following, we want to analyze these relationships as examples for cryptography in the field of mobile messaging based on the Echo protocol. It is ideal for exploring further models, findings and research needs in the contexts mentioned above and their intersections.

3 The Echo Protocol: Networking Encrypting Devices

So what does a microprocessor architecture look like that can map the encrypting and routing respective forwarding character of the Echo protocol?

Let us first describe the basics of the Echo encryption protocol.

The Echo Protocol was conceived around 2012 and published in the middle of 2013 in the software Spot-On Encryption Suite (Edwards / et al. 2019) and in the GoldBug Messenger GUI (Adams / Maier 2016) as a customized user interface for Echo kernels.

Spot-On is an open source software for encryption that enables e-mail, chat, file transfer and web search in a URL database in addition to other cryptographic functions and tools.

The software shows numerous innovations in the cryptographic and graph-theoretical field such as Cryptographic Calling, Secret Streams, the setting of Gold Bugs (passwords on e-mails) or the "Patch Points" for "private application pass thoughts" - a kind VPN tunnel for applications connected via the local host, which due to a traditional program code alone do not yet have encryption and which can establish the encrypted connection via the Spot-On Encryption Suite software (even with the McEliece algorithm).

GoldBug (instead of: Gold Bug) is a further design of a user interface that is adapted to a messenger in chat style and can also address every echo kernel or messenger server (listener) (Adams / Maier 2016). The name is reminiscent of Edgar Allan Poe, who described a cryptogram in his short story of the same name.

The Spot-On software is written in C++ and compatible with the Smoke Chat Messenger software written in Java for Android with the SmokeStack Android server, which, among other things, established the cryptographic innovation of Fiasco Forwarding with the Fiasco Keys (as a further development of the Signal Protocol) and the key transport problem solved with Secret Streams and the Juggernaut Keys. Cryptographic Discovery is also integrated in this server (see Smoke Technical Documentation 2019).

The basis of C++ as well as Java software is the Echo protocol, which can be characterized as follows:

Basically, every message sent, every packet sent, is encrypted within the Echo protocol. This can also be done by multi-encryption, i.e. ciphertext is converted into ciphertext once again using another algorithm.

Second: In principle, every packet is forwarded from a node to all the neighbors connected in the network.

As a third criterion for the Echo, the so-called echo match is defined as follows: the ciphertext converted back by a key is hashed and compared with the enclosed hash of the original message. If both hashes match, the correct key has been used for decoding and the conversion of ciphertext to plaintext can be read successfully by the user (see Gasakis / Schmidt 2018).

Hybrid multi-encryption is another outstanding innovation of the Echo: Multi-encryption means multiple encryption on different levels: The authors Linda Bertram and Gunther van Dooble (2019) write:

"Applied programming of hybrid encryption (means in the end that different variants are used at the same time or one after the other) finally led this theoretical and so far little-studied concept of Multi-Encryption with its variety of options into practical application processes. It is with the Multi-Encryption not only about encrypting a ciphertext again.

It's also about possibly changing the algorithm of encryption in the second round. While an algorithm knows several rounds, operations, repetitions of e.g. substitutions, multi-enc...