Anonymous Public-Key Cipher with Tag, Commitment, and MAC Verification
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Solution Overview
Problem
Conventional public key encryption methods fail to ensure sufficient anonymity as the recipient of the ciphertext can be identified from the public key, compromising security.
Innovation Solution
A cipher system incorporating a tag-based encryption scheme, weak commitment scheme, and message authentication code scheme is used to generate and verify ciphertexts, ensuring anonymity through a public key encryption scheme that includes a key generation, encryption, and decryption process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a public key is included in the ciphertext to enable decryption, then decryption functionality is improved, but anonymity is worsened because the recipient can be identified from the ciphertext
Solution Approach 1:
The patent introduces a tag-based encryption scheme as an intermediary layer between the plaintext and the public key. The ciphertext is structured as (tag, c) where the tag serves as a mediator that enables decryption functionality without directly exposing the public key or recipient identity in the ciphertext structure
Solution Approach 2:
The patent applies different quality requirements to different parts of the encryption system: the tag component provides anonymity by not revealing recipient identity, while the ciphertext component c provides decryption functionality. This local differentiation allows each part to optimize for its specific function without compromising the other
2Loss of information
If tag-based encryption is used to ensure anonymity, then anonymity is improved, but system complexity increases due to the need for additional components (commitment scheme, MAC scheme)
Solution Approach 1:
The patent merges multiple cryptographic primitives (tag-based encryption, commitment scheme, and MAC scheme) into a unified encryption framework. The encryption algorithm combines these components to produce a ciphertext structure (tag, c) that integrates anonymity and authentication functions, reducing the need for separate independent systems
Solution Approach 2:
The tag-based encryption scheme serves multiple functions simultaneously: it provides anonymity by hiding recipient identity, enables decryption through the tag verification process, and ensures integrity through the MAC scheme. This multi-functionality reduces overall system complexity by consolidating multiple security requirements into a single unified approach
Data Source
AI summary
A cipher system that performs encryption and decryption by a public key encryption scheme including schemes of tag-based encryption, weak commitment, and message authentication code, is configured to, using a security parameter, generate an encryption key, a decryption key, and a common parameter, and use the encryption key and the common parameter as an encryption key and the decryption key as a decryption key of the public key encryption scheme; generate a random number, a commitment, and a decommitment, generate a ciphertext using a plaintext to be encrypted, generate a tag, and use the commitment, the ciphertext, and the tag as a ciphertext of the public key encryption scheme; and parse the ciphertext into the commitment, the ciphertext, and the tag, generate a plaintext and a decommitment, verify whether committing to a random number value has succeeded, and verify the tag in a case where the committing has succeeded.