Smart Card Hash Signing for Large Document Security
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Solution Overview
Problem
The challenge in electronic commerce and e-government is the trusted digital signing of online documents, where storing a private key on a personal computer compromises security due to reliance on the computer's security, and smart cards with limited memory face challenges in signing large documents.
Innovation Solution
Generate a first hash value of the document using a first hash function and send it to a smart card with limited memory, which signs the hash value using a second hash function and a private key, generating a second hash value for authentication, allowing for secure digital signatures without storing the private key on the smart card.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the information source (large document) is sent to the smart card for signing, then the smart card can perform the signing operation, but the smart card's limited memory cannot accommodate the large document
Solution Approach 1:
The patent extracts only the essential cryptographic element (hash value) from the complete information source, sending only this condensed representation to the smart card instead of the entire large document. This extraction allows the smart card to perform signing operations on a manageable data size while maintaining the security integrity of the original document.
Solution Approach 2:
The patent transforms the information source from its original large format into a compact hash value representation, changing the data parameter from full document size to a fixed-size cryptographic digest. This parameter transformation enables the smart card to handle the data within its memory constraints while preserving the ability to generate secure digital signatures.
2Ease of operation
If the private key is stored on the personal computer, then the signing process is convenient, but the security is compromised due to reliance on the computer's security
Solution Approach 1:
The smart card serves as a secure intermediary device that holds the private key in a protected environment. Instead of storing the private key directly on the personal computer, the system uses the smart card as an intermediate secure storage medium, allowing convenient signing operations while maintaining security through the card's protected key management.
3Reliability
If the private key is stored on the smart card, then the security is improved, but the smart card's limited memory cannot store large documents
Solution Approach 1:
The system extracts only the necessary cryptographic data (hash value of the information source) and sends it to the smart card, leaving the large original document on the external computing device. This extraction approach allows the smart card to maintain security by keeping the private key secure while avoiding the need to store large documents within its limited memory.
4Quantity of substance
If a hash value is generated and sent to the smart card instead of the information source, then the memory constraint is resolved, but an additional processing step is required
Solution Approach 1:
The hash value is generated in advance on the external computing device before being sent to the smart card. This preliminary action of pre-computing the hash value eliminates the need for the smart card to process or store the large original document, resolving the memory constraint while the added processing step is performed on a device with sufficient computational resources.
Data Source
AI summary
Disclosed herein are system, method, and computer program product embodiments for signing a document by generating a hash value using a smart card. The smart card can receive from a computing device a first hash value generated for the document based on a first hash function, determine a private key based on a private key information stored on the smart card, sign the first hash value by generating a second hash value based on the first hash value using a second hash function and the private key. The second hash value is to authenticate that the second hash value is generated by the smart card based on the first hash value and the private key. The smart card can further assemble a signature package including the second hash value, and transmit the signature package to the computing device.