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Title: RLWE同態加密技術落實於二元分類器
RLWE-Based Homomorphic Data Encryption for Binary Classifier
Authors: 黃為德
Contributors: 胡毓忠
Hu, Yuh-Jong
Keywords: Ring learning with errors
Ring learning with errors
Homomorphic encryption
Machine learning
Binary classifier
Support vector machine
Decision tree
Date: 2019
Issue Date: 2019-03-07 11:59:36 (UTC+8)
Abstract: 隨著公有雲技術的運用日漸廣泛,現今企業越來越傾向將對外資通服務建立在雲端伺服器上,然而現行雲端服務的安全機制只涵蓋傳輸階段與儲存階段,而每個階段必須運用不同的加密演算法;且在資料進行運算時仍必須還原回明文,從而導致運算期間有資料外洩的疑慮。本研究希望藉由以Ring-Learning With Errors(RLWE)為基礎的同態加密(Homomorphic Encryption)技術,以單一種加密機制達成資料在傳輸、儲存與運算三個階段的保護。
本研究使用Medical Datasets Heart Disease來對支援向量機(Support Vector Machine, SVM)及決策樹(Decision Tree)等兩類機器學習演算法的二元分類器訓練,再透過同態加密技術來對模型內的係數與輸入資料進行加密後,進行密文間的各類同態運算,並將密文運算結果解密後,與明文、未加密的運算結果進行比較,確認在加密情形下運算得出的分類結果是否能保持正確,並就加密運算的額外時間成本與空間成本提出質化與量化的比較分析。
With the increasing use of public cloud technology, enterprises are increasingly inclined to establish foreign-funded services on the cloud server. However, the current security mechanism of cloud services only covers the transmission phase and storage phase, and each phase must use different Encryption algorithm; and the data must still be restored back to the plaintext when the operation is performed, resulting in doubts about data leakage during the operation. This study hopes to achieve the protection of data in the three stages of transmission, storage and operation by a single encryption mechanism by using Homomorphic Encryption based on Ring-Learning With Errors (RLWE).

In this study, Medical Datasets Heart Disease is used to train binary classifiers of two types of machine learning algorithms, such as Support Vector Machine (SVM) and Decision Tree, and then through homomorphic encryption technology. After the coefficient is encrypted with the input data, various homomorphic operations between the ciphertexts are performed, and the ciphertext operation results are decrypted, and compared with the plaintext and unencrypted operation results, and the classification result obtained by the operation in the encryption case is confirmed. Whether it can be kept correct, and a comparative analysis of the quality and cost of the extra time cost and space cost of the encryption operation.
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