Secure Element Challenge-Response Protocol for Offline Security Actions
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Solution Overview
Problem
Existing communication protocols between terminals and secure elements in Integrated Circuit Cards (ICC) lack the ability to efficiently convey additional data or instructions during challenge-response exchanges, particularly in offline transactions, which can limit security actions such as blocking unauthorized cards.
Innovation Solution
A method is introduced where a terminal determines if a secure element is on a blacklist and, if so, sends a modified encrypted response with an operation code to the secure element, allowing the secure element to perform specific security actions, such as blocking, by performing bit-wise operations on the challenge and additional data elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a modified encrypted response with operation code is sent to convey additional data, then the secure element can perform security actions like blocking, but the message length would need to be extended
Solution Approach 1:
The operation code is nested within the existing challenge-response message structure by XORing it with the challenge data. This allows the operation code to be embedded in the same message without increasing the overall message length, as the operation code is hidden within the existing data fields through the XOR operation.
Solution Approach 2:
The operation code and challenge data are merged through XOR operation to create a modified challenge that contains both pieces of information. This combining allows the terminal to send both the challenge and the operation code in a single message without requiring separate communication channels or extending the message structure.
2Adaptability or versatility
If existing challenge-response protocols are used, then compatibility with existing systems is maintained, but the ability to convey additional data or instructions is limited
Solution Approach 1:
The protocol utilizes changes in the challenge parameter by XORing it with the operation code. This allows the existing challenge-response mechanism to carry additional information by modifying the challenge parameter itself, rather than introducing new protocol structures or message formats that would increase complexity.
Solution Approach 2:
The modified challenge serves multiple functions: it still acts as a cryptographic challenge for authentication while simultaneously carrying the operation code that instructs the secure element to perform specific actions. This multi-functionality allows the existing protocol framework to handle both authentication and command transmission without requiring separate protocols.
Data Source
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AI summary
A method of communicating between a terminal (20) and a secure element (10) comprises determining a challenge and sending the challenge (122) to the terminal (20). The secure element receives a response (124, 126) from the terminal (20) comprising the challenge and personal identification number, PIN, data. The response is encrypted with a key. The secure element determines (132) if the challenge received in the response matches the challenge sent to the terminal (20). If the challenge received in the response does not match the challenge sent to the terminal (20), the secure element performs a computation (133) using the received challenge and the sent challenge. The secure element recovers a data element (136) carried by the response. The data element (136) is indicative of an action to be performed by the secure element. The data element can be an encrypted operation code.