Attribute-Based Encryption With PQC Verification of Decryption Conditions
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Solution Overview
Problem
Conventional attribute based encryption (ABE) systems face challenges in achieving both flexibility and efficiency of access control while providing security against quantum computers, with issues including inefficient data sizes and encryption processing times, and inability to verify decryption conditions without using secret keys.
Innovation Solution
A cryptosystem that employs double encryption using attribute based encryption and post quantum cryptography, where a decryption-possible condition is encrypted using a combination of public keys from both systems, with parts of the ciphertext randomized to ensure security against quantum computers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If attribute based encryption is configured based on lattice cryptography technology to provide quantum resistance, then security against quantum computers is improved, but encryption processing time and data size efficiency deteriorate
Solution Approach 1:
The encryption process is divided into two independent stages: first, attribute-based encryption is applied to the plaintext to generate an ABE ciphertext; second, post-quantum cryptographic encryption is applied to the ABE ciphertext to generate a final PQC-encrypted ciphertext. This segmentation allows each encryption method to operate independently, optimizing for their respective strengths while avoiding the performance penalties of integrated approaches.
Solution Approach 2:
The patent implements nested encryption where post-quantum cryptographic encryption is applied around the attribute-based encryption ciphertext. The PQC encryption layer contains the ABE ciphertext layer, creating a nested structure where the inner layer (ABE) provides fine-grained access control while the outer layer (PQC) provides quantum resistance. This nesting allows both cryptographic systems to function efficiently without interfering with each other's performance characteristics.
2Reliability
If attribute based encryption is configured based on lattice cryptography technology to provide quantum resistance, then security against quantum computers is improved, but ciphertext data size efficiency deteriorates
Solution Approach 1:
The encryption process is divided into two independent stages: first, attribute-based encryption is applied to the plaintext to generate an ABE ciphertext; second, post-quantum cryptographic encryption is applied to the ABE ciphertext to generate a final PQC-encrypted ciphertext. This segmentation allows each encryption method to operate independently, optimizing for their respective strengths while avoiding the performance penalties of integrated approaches.
Solution Approach 2:
The patent implements nested encryption where post-quantum cryptographic encryption is applied around the attribute-based encryption ciphertext. The PQC encryption layer contains the ABE ciphertext layer, creating a nested structure where the inner layer (ABE) provides fine-grained access control while the outer layer (PQC) provides quantum resistance. This nesting allows both cryptographic systems to function efficiently without interfering with each other's performance characteristics.
3Adaptability or versatility
If key policy type attribute based encryption is used where decryption condition is set to user secret key, then flexibility of access control is improved, but ability to verify decryption condition without decryption deteriorates
Solution Approach 1:
The patent extracts the decryption condition verification from the decryption process itself. By applying post-quantum cryptographic encryption to the ABE ciphertext, the system creates a separate verification layer where the PQC decryption key can validate whether the ABE decryption conditions are satisfied without requiring actual decryption of the plaintext. This extraction enables independent verification of access rights.
Solution Approach 2:
The post-quantum cryptographic layer acts as an intermediary between the access control policy and the decryption operation. The PQC encryption/decryption mechanism serves as a mediator that can verify whether the holder of a secret key satisfies the decryption conditions without revealing the plaintext or requiring full decryption. This intermediary layer enables verification of decryption eligibility separate from the actual decryption process.
Data Source
AI summary
An encryption unit (403) that an encryption apparatus (400) includes, when a user secret key SKΓ is generated using a secret key MSK of attribute based encryption and a set of attributes Γ corresponding to a decryption-possible condition L, generates a key K and a ciphertext P corresponding to the key K by encrypting the decryption-possible condition L using, as an encryption key of the attribute based encryption, a key PK consisting of a public key MPK corresponding to the secret key MSK and a public key PQCPK of post quantum cryptography, regards a part of the ciphertext P where the decryption-possible condition L is encrypted based on a secret value as P-D, regards a part of the ciphertext P where the secret value that is shared is encrypted as P-SS, and generates K′ and P′-D by randomizing each of the key K and the P-D using a random number R, and generates a ciphertext C by encrypting data consisting of the P-D and the random number R using the public key PQCPK. Here, the P-SS, the P′-D, and the K′ are decryption-possible verification parameters corresponding to the user secret key SKΓ.