於雲端運算系統中使用混合密碼學與兩階段加密方法之分析

Analysis of a Double-stage Encryption Scheme Using Hybrid Cryptography to Enhance Data Security in Cloud Computing Systems

最近，網路使用者對於將其個人敏感資訊（例如銀行帳戶資料、健康紀錄和其他重要資訊）儲存在雲端空間會感到擔憂，因這些資訊在雲端很容易受到第三方的攻擊且現今多種威脅模式亦影響到雲端的安全性。本研究將提出一使用混合密碼學之兩階段加密方法，以消除基於雲端系統中的弱點並使其在雲端環境之資料存取變得更安全。本系統先使用RSA對檔案進行加密後，再使用AES金鑰對已加密之檔案進行加密，並透過雜湊函式以確保加密金鑰之安全性。本雲端系統透過Python及MongoDB進行實作並藉由雪崩效應測試進行分析，其分析結果顯示本系統所提出之兩階段加密方法比單獨使用AES和RSA單一加密方法之安全性高出17%，這也意味著本研究所提出之方法會讓雲端系統變得更加安全。

Recently, network users have been scared of storing sensitive information, such as bank details, health records, and other vital information, on the Internet because it is vulnerable to attack by a third party. Several threat models are impacting the security of the cloud. Having a secure cloud system will help to be at ease in using cloud computing facilities. This study aims at providing a cryptography approach to eliminating the vulnerabilities in the cloud-based system, and making access and data storage in the cloud very safe. The system uses Rivest-Shamir-Adleman (RSA) to encrypt files and the Advanced Encryption Standard (AES) key to encrypt the encrypted files. The hash function is used for extra key security, and Python programming language was used to implement the system, and for cloud storage, MongoDB was used. Generally, results indicate that the Double Stage Encryption (DSE) takes an average time for encryption of 83% and decryption of 75% compared to RSA and AES singly. The RSA is 68% faster than AES during the encryption process, but there is no significant difference between the two during decryption. The Avalanche effect testing showed the DSE to be 17% higher than singly testing AES and RSA, which implies it is more secure than RSA and AES as single encryption schemes. Therefore, the study recommends using DSE to secure valuable data on the cloud.