Fully Homomorphic Encryption via Ring Isomorphism

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Solution Overview

Problem

Existing fully homomorphic encryption schemes are inefficient due to processor-intensive algorithms and noise accumulation during computations, limiting their practical application in fields like cloud computing and private data processing.

Innovation Solution

A system and method for fully homomorphic encryption based on homomorphisms between rings, utilizing a processor to generate and manage public and private rings, enabling efficient computation on encrypted data without noise accumulation, and providing unconditional security against ciphertext-only attacks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If Gentry's fully homomorphic encryption scheme is used, then arbitrary functions can be computed on encrypted data, but the algorithm is too inefficient to be practical

Engineering Contradiction:
Improvecomputation capability on encrypted dataVSAvoidencryption speed
Core Design Contradiction:
Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent extracts and eliminates the bootstrapping step from Gentry's FHE scheme, retaining only the essential homomorphic encryption components. This removes the computationally intensive noise reduction procedure while preserving the core ability to perform arbitrary computations on encrypted data, achieving practical encryption speeds.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent segments the FHE functionality into two distinct parts: (1) the homomorphic encryption scheme for computing on encrypted data, and (2) the bootstrapping procedure for noise management. By separating these functions, the patent enables practical deployment of homomorphic encryption for suitable workloads without the overhead of full bootstrapping.

Inventive Principle:
Principle #1Segmentation

2Reliability

If bootstrapping is performed to reduce noise accumulation, then computation accuracy is maintained, but the procedure is expensive and limits real-life applications

Engineering Contradiction:
Improvecomputation accuracyVSAvoidrecryption time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent applies partial action by performing bootstrapping only when necessary - specifically, only when noise accumulation threatens to compromise decryption accuracy. Rather than applying bootstrapping continuously or excessively, the system monitors noise levels and triggers recryption only at critical thresholds, thereby maintaining accuracy while minimizing time loss.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The patent implements preliminary action by pre-establishing noise thresholds and prediction mechanisms that anticipate when bootstrapping will be needed. This allows the system to prepare for and execute recryption operations more efficiently, reducing the overall time impact by acting in advance rather than reactively.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If existing FHE solutions are implemented, then semantic security is provided, but the algorithms are processor-intensive and inefficient

Engineering Contradiction:
Improvesemantic securityVSAvoidprocessor intensity
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent employs computationally lighter encryption operations that can be discarded and refreshed more frequently without compromising security. By using simpler homomorphic operations with controlled lifetime and refresh intervals, the system maintains semantic security while significantly reducing processor intensity compared to Gentry's scheme.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent changes key parameters of the encryption scheme, including the underlying mathematical structures and parameter selections, to optimize the balance between security and computational efficiency. These parameter adjustments reduce processor intensity while preserving the fundamental security guarantees of semantic security.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS10396976B2System and method for private-key fully homomorphic encryption and private search between rings
Publication Date: 2019.08.27 RES FOUND THE CITY UNIV OF NEW YORK
  • US10396976B2 patent drawing
  • US10396976B2 patent drawing
  • US10396976B2 patent drawing

AI summary

A system for producing a public ring that is fully homomorphically encrypted. The system comprises a processor which generates a first presentation G of a ring, wherein G=x, y|x2=0, y2=0, xy+(p+1)yx=1, where x and y are generators and p is a first private prime number. The system further generates a second presentation H of the ring. H is defined as follows: H=x, y, t|x2=0, y2=0, t=m1yx, xy+m2yx+t=1. In addition, m1 and m2 are positive integers and p+1=m1+m2, wherein t is a generator and the first presentation G and the second presentation H are isomorphic. The system further produces a public ring Ĥ that is fully homomorphically encrypted, where:H^=〈x,y,t❘N·1=1,x2=1,y2=0,xyx=x,yxy=y,tx=0,yt=0,t2=t+m22-m2m1⁢tyx〉,N=pq and further, q is a second private prime number, and the public ring Ĥ is further, publically available. A corresponding method is also disclosed.