Secure Element Token Verification for Remote Key Encryption
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Solution Overview
Problem
Existing remote key encryption protocols (RKEP) face security vulnerabilities such as chosen clear text attacks, exposure of message keys during communication, and high computational costs due to hash condensate calculations performed by host devices.
Innovation Solution
A method and system for encrypting and decrypting data using a host device and a secure device, where the host device requests and verifies a token generated by the secure device, allowing secure key generation and transmission only if the token is legitimate, thereby reducing computational burden and enhancing security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hash calculations are performed for each message by the host device, then message key generation is enabled, but computational cost in terms of cycles and memory increases
Solution Approach 1:
The patent applies preliminary action by pre-computing and storing hash values of frequently used messages in a lookup table within the secure element. When a message needs encryption, the system first checks the lookup table for a matching hash value before performing actual hash calculations. This preliminary preparation eliminates redundant computational operations while maintaining security, directly resolving the contradiction between security requirements and computational complexity.
2Productivity
If the message key KP is transmitted to the host device, then encryption can be performed, but the key is exposed on the communication link and subject to interception
Solution Approach 1:
The patent extracts the sensitive message key KP from the communication channel by implementing a challenge-response authentication mechanism. Instead of transmitting KP directly, the host device sends a challenge that is processed by the secure element to generate a response. This extraction approach allows the key material to remain confined within the secure element boundaries, eliminating exposure on the communication link while still enabling fast encryption operations.
Solution Approach 2:
The patent introduces an intermediary challenge-response mechanism between the host device and secure element. The challenge acts as an intermediary that enables key derivation without direct key transmission. The host sends a challenge, the secure element processes it using the secret key to generate a response, and this response serves as the basis for encryption. This intermediary approach maintains encryption speed while preventing key exposure on the communication channel.
3Ease of operation
If a chosen-plaintext attack is allowed, then the attacker can submit texts to the secure device and retrieve encrypted KP versions, but security is compromised
Solution Approach 1:
The patent applies preliminary anti-action by implementing a challenge-response authentication mechanism that prevents chosen-plaintext attacks before they can occur. The challenge step requires the host to prove knowledge of the message key through cryptographic verification. This preliminary defensive action blocks attackers from submitting arbitrary plaintexts to retrieve encrypted versions, as the authentication check fails for unauthorized attempts. The protocol maintains simplicity while incorporating this preemptive security measure.
Data Source
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AI summary
The invention relates to a method for encrypting a message (P) by a host device (MCU), comprising the steps of: - requesting (RK1) by the host device (MCU) a message key (KP) from a secure device (SE), - generating (GK1) by the secure device (SE) the message key (KP) using a secret key (KSE) stored in the secure device and not communicated to the host device, characterized in that it includes the preliminary steps of: - requesting (RT1) by the host device a token (T) from the secure device, - generating (GT1) the token (T) by the secure device, and transmitting the token to the host device, in that the step of requesting (RK1) a message key by the host device includes the transmission of the token, and in that the step of generating (GK1) the message key by the secure device is preceded by a step of verifying the legitimacy of the token.