HCE NFC Device Security via TEE Trustlet and SE Integration
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Solution Overview
Problem
NFC-enabled devices, particularly those using host card emulation (HCE), face significant security challenges in ensuring end-to-end trust and security for contactless transactions, as they lack standardized secure channels between the secure element (SE) and the trusted execution environment (TEE), leading to vulnerabilities in sensitive data handling.
Innovation Solution
Implementing a method that utilizes a trustlet in the TEE to validate and encrypt data from the SE, establishing a secure channel with the host OS for secure data transmission, and employing a one-time code for authentication, ensuring that only validated, digitally signed data is sent to external devices, thereby enhancing security and trust in contactless transactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If host card emulation (HCE) is used in NFC-enabled devices, then processing power and versatility are improved, but security and trust in contactless transactions deteriorate
Solution Approach 1:
A trustlet running in the TEE acts as an intermediary between the HCE application in the host OS and the external NFC controller. The trustlet validates security requirements, establishes secure channels, and manages cryptographic operations, thereby bridging the security gap between the untrusted host OS and the external device while allowing HCE to maintain its processing advantages
Solution Approach 2:
The system segments security functions from general processing functions. The TEE is divided into a trustlet that handles only security-critical operations (validation, encryption, authentication) while the host OS handles general HCE processing. This segmentation allows the host OS to provide full processing power while the TEE ensures security isolation
2Reliability
If a standardized secure channel is established between SE and TEE, then security is improved, but device complexity increases
Solution Approach 1:
The trustlet provides universal security services for multiple HCE applications simultaneously. Rather than implementing separate secure channels for each application, the trustlet acts as a universal intermediary that can service multiple applications through standardized interfaces, reducing overall system complexity while maintaining security
Solution Approach 2:
The trustlet autonomously manages security operations including validating security requirements, establishing secure channels, performing cryptographic validation, and authenticating external devices. This self-service capability eliminates the need for complex external security management infrastructure
3Reliability
If security validation and encryption are performed for all data, then security is improved, but processing time and energy consumption increase
Solution Approach 1:
The trustlet performs security validation and encryption only on data and operations that require security protection, rather than applying security measures to all HCE operations uniformly. This partial action approach applies security selectively based on security requirements, reducing unnecessary processing overhead while maintaining security where needed
Data Source
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AI summary
In a device that is both NFC-enabled and TEE-enabled, and has a secure element (SE), an HCE based software application acts as a front-end/proxy and processes non-sensitive security functions, while a trusted application in the TEE and an applet on the SE cooperate to process security-sensitive functions. An end-to-end security relationship may be established between the SIM, TEE and a SAM (Secure Authentication Module) provided for a second NFC-enabled device (e.g. a contactless reader) that communicates with the first device in a contactless manner. The solution integrates HCE, TEE, SE and SAM for enabling secure contactless applications, and it also supports advanced security measures.