用於共享式訊息之公開金鑰加密系統

Abstract

在本論文裡，我們提出一個適用於共享式訊息之公開金鑰加密系統。在訊息被多個儲存伺服器共享的情況下，我們可以利用這個公開金鑰加密系統將訊息加密成密文，並且保證即使一定數量的儲存伺服器合作，仍無法得知關於共享式訊息的任何資訊。這樣的系統特別可以運用在保護分散式儲存系統內的使用者隱私權。我們提出一個非互動式的公開金鑰加密系統用於共享式訊息的加密，並且證明在Decisional Diffie-Hellman assumption 底下能夠抵擋惡意的攻擊者。本論文是第一篇適用於分享式訊息的公開金鑰加密系統，並且是 有效率的，能夠運用至大規模的系統。

This paper proposed a public key encryption scheme for a shared message. The message is shared among storage servers such that the message can be encrypted into a ciphertext without leaking any information even if a given threshold of storage servers cooperate. This is especially suitable for the applications, for example, distributed storage systems. We present a non-interactive public key encryption scheme on a shared message and prove that it is semantically secure against malicious adversaries, under the Decisional Diffe-Hellman assumption. This is the first public key encryption performed on a shared plaintext. Our scheme is e?cient and practical for large scale systems.