Towercell - Multi-Level Safety Protection

Fully protect system security from the bottom of the hardware to the cloud

Related Background

With the continuous integration of information technology, the Internet and the automobile industry, automotive network connectivity and intelligence have become an inevitable trend in the development of the automotive industry. As of August 2021, the number of connected car users in China has exceeded 50 million. Most modern vehicles have more than 100 ECUs, and these ECUs are running more than 100 million lines of code. For a networked car, from an isolated and closed network environment to a complex and diverse Internet environment, many functions based on the closed network environment will undergo disruptive changes in design, and network information security will become the biggest security challenge. Under the complex automotive architecture, the threats faced by the in-vehicle system may be multi-layered, from firmware flushing at the hardware level, to ROOT permission theft at the system level, to APP vulnerability and sensitive information theft at the application level, and so on. Therefore, to ensure the overall security of IVI, it is necessary to establish a multi-layered three-dimensional defense strategy.


T6 Architecture

Any security hole in the framework could result in an attacker taking full control of the device.The TowerCell platform provides multi-level protection policies to ensure that data at all levels and phases cannot be tampered with to ensure system security.By formulating a complete set of three-dimensional security policies from the hardware layer to the application layer, from the terminal to the cloud to ensure the overall security of the system from the start-up stage to the operation process.

Hardware layer:

Secure start-up inspection equipment completeness and establishment of a trusted execution environment

Trusted Execution Environment

TowerCell will be based on the chip's existing isolation technology (such as Trustzone technology under the ARM architecture and SGX technology under the Intel architecture, etc.). The resources of the chip will be divided into a normal world and a secure world, which we call Trusted execution environment. Under TEE, we will run a security OS TKCORE OS: Trustkernel's self-developed trustworthy operating system. The secure application (TA Trusted application) that carries the user's business will run on top of this trusted OS. When storing data under TEE, TKCORE OS encrypts all data and the key is held by TKCORE OS to ensure that the data cannot be stolen. The key is held by TKCORE OS to ensure that the data cannot be stolen. Also, data stored under TEE cannot be accessed by third parties without authorization. This ensures that the stored data cannot be tampered with. We generate an identity ID for each device under TEE, which uniquely identifies the device. The private key is strictly held by TKCORE OS, and the public key is uploaded to the server at the production line stage. Users can establish a PKI system based on this pair of root keys

Start Security

TowerCell will create a secure boot mechanism for the device based on the characteristics of the chip. At boot time, the initial checksum is done by a key rooted in the device hardware (the hardware mechanism ensures that the burn-in of this key is one-time and cannot be replaced). Then, during the boot process, each component makes a checksum on the next component. If the checksum fails, the TowerCell will disable certain services or simply hang the entire device to prevent further damage. With Secure Boot, we can ensure that any component that is illegally replaced or tampered with will cause the device to hang. This ensures that security services cannot be bypassed by firmware flushing

System layer:

Active defense system detects kernel status in real time to prevent problems before they occur

The vulnerability risk associated with increasing code volume can also spike significantly. However, for an operating system such as Android with over 10 million lines of code. It is certainly not realistic to completely eliminate the creation of vulnerabilities, and not all vulnerabilities create intuitive harm and loss to users. Rather, the existence of this vulnerability may be exploited by third parties to tamper with key kernel data, obtain more advanced privileges, and then attack system components to obtain user access. Therefore, the most important thing to do to prevent vulnerabilities is to make sure that the most important thing is to have the ability to monitor and manage the critical data nodes of the kernel.


TowerCell will run our own Hypervisor THEE in EL2 mode (Hypervisor) to monitor and manage the kernel by THEE.

Control flow protection

Control flow integrity enhancement. For current ROP attacks, based on hardware features as well as compiler Combined with existing Linux defense mechanisms (such as KASLR, LLVM CFI) to defend against ROP-based kernel attacks.

Isolation guarantee

THEE runs in a secure zone isolated from the Linux system. Currently THEE is running in EL2 mode (Hypervisor). This ensures that THEE is isolated from Linux, while at the same time being able to effectively monitor and protect Linux.

Critical Data Integrity

Kernel state critical data can only be legally modified by authorized objects. Identify and protect critical data in the kernel by keeping a Shadow Backup (read-only) in Linux, and the main content is stored in THEE(read and writeable), which is authorized by THEE with a configured access policy.

Self-security and integrity assurance

THEE is a lightweight Hypervisor developed by Trustkernel itself, which can effectively prevent vulnerabilities because of its small size (a few thousand lines). At the same time, the combination of hardware-level security boot effectively ensures that THEE itself can be loaded intact.

Application layer

Trust++ Open Trusted Execution Environment Security Capabilities to Protect Massive Number of Applications

The main problem for application protection is that it is not possible to effectively secure this part of the business in the process of carrying out the core business. In most scenarios, this part of the core business is exposed or run in a complex system environment with simple encryption.


At the application layer, TowerCell uses Trust++, a Trusted Execution Environment (TEE)-based application security solution for application vendors. It is mainly used to solve the code, data and business security problems of applications in smart devices, and provide a secure operating environment for users' sensitive business.

Ease of use and cross-platform

Based on Trust++'s security API and SDK, security applications developed by application vendors can run securely on all smart devices (including cell phones, tablets, etc.) and platforms (including Android, iOS, etc.).


Trust++ leverages the most secure mechanisms available in the device (including hardware and software mechanisms such as ARM TrustZone, virtualization, Intel SGX, etc.). virtualization, Intel SGX, etc.), combined with the original native encryption execution engine, compiler security, code protection, and The application is secure by leveraging the most secure mechanisms available in the device (including hardware and software mechanisms such as ARM TrustZone, virtualization, Intel SGX, etc.).

More base libraries of security features

Trust++ provides feature-rich security application scenarios, users can use the security API and SDK provided by Trust++ to use such as: secure UI, secure storage, authentication and other rich features, greatly reducing the difficulty of user development.


DTM platform real-time monitoring, timely response

We can use different protection strategies to minimize the creation of vulnerabilities or reduce the damage caused by vulnerabilities. But for a vulnerability that has been created, we still need a good strategy to fix it. For operations and maintenance personnel, to be able to timely collect information related to the vulnerability generated in the device terminal. to be able to timely develop a good security policy issued in a timely manner.


At the application layer, TowerCell uses Trust++ to secure applications. The Trust++ product is an application security solution for application vendors based on the Trusted Execution Environment TEE. It is mainly used to solve the code, data and business security problems of applications in smart devices, and provide a secure operating environment for users' sensitive business.

Identify problems

Drill down into the OS kernel and application Capture key events and correlate them for analysis. At the device endpoint, the Real-time monitoring and management through active defense system deep into the OS kernel. Real-time feedback of device status to the cloud platform. In the case of vulnerability discovery, the kernel-related logs are uploaded to the cloud in time for analysis by relevant personnel.

Positioning problems

Visual threat presentation locates a terminal, a process and a path. The log information uploaded from the device side is classified and processed to create reports for maintenance personnel. Allow maintenance personnel to easily analyze the source of vulnerabilities

Solving problems

Customize and implement security policies, and issue the corresponding policies through the remote management platform. After the maintenance staff has formulated the corresponding security policy in the form of trusted application updates, it is transmitted to the device side in real time through the cloud platform. Under the TEE at the device side, the vulnerability of the system is fixed by the updated trusted application.

Application Cases

PKI Application Scenarios


Trusted root generation process


PKI activation process

In the process of authentication on the device side and in the cloud, it is a more effective practice to establish a PKI system. However, for PKI, if the absolute security of the activation process, key certificate storage, etc. cannot be guaranteed, then even if PKI is used, it cannot achieve the expected security protection. The traditional PKI system implants a set of keys into the device at the production line stage as the basis for subsequent PKI activation. TowerCell generates a pair of root keys for each device under TEE at the production line stage. The private key is strictly held by the TKCORE OS of the device and will not be disclosed in any form. The generated public key will be exported and uploaded to Trustkernel's key management server for unified management. During the device activation phase, it is important to ensure the security of the root key usage environment. TowerCell provides a secure activation environment for the device. The device will sign and upload the authentication information to the manufacturer's PKI server in the TEE environment, and after receiving the authentication information, the PKI server will After receiving the verification information, the PKI server sends the data to Trustkernel's key management server for verification. After receiving the verification information, the PKI server sends the data to Trustkernel's key management server for verification. With the verification result returned by Trustkernel's key management server, the PKI server decides whether to issue the PKI certificate (encryption issuance). When the device receives the encrypted PKI certificate, it will decrypt the certificate under TEE, and the PKI certificate will be stored under TEE and can only be used under TEE. The PKI certificate is stored in the TEE and can only be used under the TEE, effectively ensuring that the certificate will not be leaked. At the same time, TowerCell can control the frequency of device access to the cloud. When a single device is compromised by a malicious attacker The device may send a large amount of information to the cloud through this device to occupy the limited resources of the cloud. In this case, the TowerCell can be used to limit the frequency of access to the device to stop the damage caused by this big data flush.

Usage scenarios for Trust++

Trust++ provides rich security application scenarios, and users can use the SDK to call the relevant interface to use security features using the target language (such as JAVA).


Identity verification

Developers can call the SDK's interface to send data to a specified server to perform authentication work


Feature-rich encryption and decryption libraries

Feature-rich encryption and decryption library: Trust++ provides a powerful feature library that supports basically all encryption and decryption algorithms on the market.


Secure Storage

Trust++ builds secure runtime and storage environments by leveraging the most secure mechanisms that can be used in the device. Developers can use the interface provided by Trust++ for secure storage to securing private data such as keys.


Trustworthy UI

Trust++ provides a set of call interfaces for security UI. Users can easily design their own security UI by choosing the style and layout of their UI through the relevant interface