Cryptographic Signing with Smartcard–Server Key Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The security of cryptographic signing operations is compromised when the secret key is held in a mobile device, such as a smartphone, as it increases the risk of theft and unauthorized access.
Innovation Solution
A method and system that utilizes both a smartcard secret key and a server secret key for collective signing, establishing a secure channel between the smartcard and server to create a collective signature, which is verified using a single public key, ensuring security without relying on a trusted smartcard reader.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the secret key is held in a mobile device for user mobility, then the ability to perform signing operations in the field is improved, but the security of the secret key deteriorates due to increased risk of theft
Solution Approach 1:
The secret key is segmented into two parts: a smartcard secret key stored in a secure smartcard and a server secret key stored on a remote server. This segmentation allows the signing operation to be distributed, maintaining security while enabling field operations through the portable smartcard.
Solution Approach 2:
A smartcard acts as an intermediary device between the user and the server. It securely holds the smartcard secret key and facilitates communication with the server, enabling signing operations without requiring the user to directly access or store the complete secret key on mobile devices.
2Ease of operation
If a smartcard reader is used to facilitate signing operations, then the ease of operation is improved, but the security deteriorates if the reader needs to be trusted with sensitive information
Solution Approach 1:
The sensitive secret key material is extracted from the smartcard reader and stored instead in a secure smartcard and on a remote server. The reader only handles public keys and signature data, not the actual secret keys, eliminating the need to trust the reader with sensitive information.
Solution Approach 2:
The smartcard serves as a secure intermediary that protects the secret key from exposure to the reader. It establishes a secure channel to the server and performs cryptographic operations locally, ensuring the reader never accesses the actual secret key.
3Reliability
If collective signing with both smartcard and server keys is implemented, then the security is improved through multiple key requirements, but the device complexity increases
Solution Approach 1:
The smartcard autonomously performs cryptographic operations using its embedded secret key without requiring external processing. It independently communicates with the server, manages the secure channel, and completes signing operations, reducing the complexity burden on external systems.
Solution Approach 2:
Complex cryptographic operations are replaced by dedicated hardware in the smartcard that is designed specifically for these functions. The smartcard's embedded processor and security module handle the computational complexity, simplifying the overall system architecture.
Data Source
AI summary
it is provided a method for performing a cryptographic signing operation of a data item. The method is performed in a server and comprises the steps of: receiving, from a smartcard reader, a request for a data item to be collectively signed, the request comprising an indication of the data item and an identifier of a smartcard, wherein the collective signing requires the use of both a smartcard secret key and a server secret key for the collective signature to be valid; establishing a secure channel with the smartcard; collaborating with the smartcard over the secure channel to provide a collective signature of the data item, wherein the server bases the signature on the data item and a server secret key, wherein the server secret key is specifically associated with the smartcard secret key, resulting in a collective signature; and sending the collective signature to the smartcard reader.