Attribute-Based Encryption with Bounded Collusion Resistance
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Solution Overview
Problem
Existing attribute-based encryption (ABE) systems face challenges in providing effective collusion resistance without experiencing quadratic growth in resource usage and ciphertext size, and they are inadequate for dynamic organizational settings where user identities and roles are unknown.
Innovation Solution
Implementing an ElGamal-style encryption scheme with an 'AND' gate using a key matrix that encrypts data based on a modified disjunctive normal form (DNF) formula, ensuring decryption requires all specified attributes, thus providing bounded collusion resistance with linear growth in resources and ciphertext size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing encryption schemes implement collusion resistance, then security against collusion attacks is improved, but resource requirements and ciphertext size grow quadratically
Solution Approach 1:
The patent segments the encryption scheme into distinct functional components: attribute-based encryption for fine-grained access control, identity-based encryption for user identification, and hash functions for binding attributes to identities. This modular segmentation allows each component to contribute to collusion resistance independently, preventing quadratic growth in resource requirements while maintaining security.
Solution Approach 2:
The patent introduces a new dimensional approach by combining attribute-based encryption with identity-based encryption and hash functions. This creates a multi-dimensional security model where attributes, identities, and cryptographic bindings operate in separate but interconnected dimensions, achieving linear resource growth while providing collusion resistance.
2Reliability
If existing encryption schemes implement collusion resistance, then security against collusion attacks is improved, but ciphertext size grows quadratically
Solution Approach 1:
The ciphertext is segmented into distinct components corresponding to different encryption schemes (attribute-based encryption ciphertext, identity-based encryption ciphertext, and hash function outputs). This segmentation allows each component to contribute minimally to the overall ciphertext size, achieving linear growth rather than quadratic growth as the number of attributes increases.
Solution Approach 2:
The patent uses hash functions to create compact cryptographic bindings between attributes and identities. Instead of storing redundant attribute information multiple times, the hash function creates a compact copy that binds the attribute to the identity, significantly reducing ciphertext size while maintaining security against collusion attacks.
3Measurement precision
If attribute based encryption is used for fine-grained data sharing, then data sharing precision is improved, but vulnerability to collusion attacks increases
Solution Approach 1:
The patent applies preliminary anti-action by pre-binding user identities to attributes through cryptographic hash functions before any data sharing occurs. This preliminary binding creates a security layer that prevents users from falsely claiming attributes they do not possess, thereby preventing collusion attacks while maintaining fine-grained data sharing precision.
Solution Approach 2:
The patent introduces identity-based encryption and hash functions as intermediary layers between users and encrypted data. These intermediaries verify user identities and attribute bindings before allowing decryption, preventing collusion attacks while preserving the fine-grained access control capabilities of attribute-based encryption.
4Ease of operation
If standard public key encryption is used, then ease of operation is maintained, but fine-grained selective sharing capability is lost
Solution Approach 1:
The patent creates a universal encryption system that combines multiple encryption schemes (attribute-based encryption, identity-based encryption, and hash functions) into a single multi-functional framework. This unified system maintains the ease of operation of standard public key encryption while adding fine-grained selective sharing capabilities through attribute-based access control.
Solution Approach 2:
The patent introduces dynamic attribute-based access control policies that can be configured flexibly to meet different data sharing requirements. The system dynamically evaluates user attributes against encryption policies at decryption time, providing fine-grained selective sharing while maintaining simple encryption operations through pre-configured policies.
Data Source
AI summary
An attribute based encryption system includes a key generator configured to generate a cyclic group (G) having a prime order q; generate an attribute key matrix (M); generate a master public key (MPK) based, at least in part, on the group (G) and (M); generate a master secret key (MSK) based on a first vector s and a second vector t that represent an encryption policy; generate a user secret key based, at least in part, on the MSK and on a set of one or more user attributes; and send the user secret key to a user device, wherein a ciphertext message can be successfully decrypted if a vector y associated with attributes of the user associated with the user secret key is orthogonal to each row of a set of rows of M selected according to a set of authorization attributes used to encrypt the ciphertext message.