With the greater development in internet, in medical field, all the confidential information about the patients and their test results are maintained in any of the remote servers around the world. Because of the confidentiality to be maintained in case of handling the patient related data, it is very crucial that the data is handled only by the authorized personnel. In the conventional method of data storage, the data are normally encrypted in the patient’s side and then they are kept securely in remote cloud server. So, the patient is empowered to decide the visibility of his data, hence becomes the data owner. But, the main disadvantage of this approach is its restricted data availability for the doctors who need to access the medical data. In this paper we propose two dynamic and efficient cryptosystems for secure storage and access of medical data. First algorithm exploits the High Secure Encryption Standard scheme, which has the advantage of making an encrypted data stored in the remote cloud is available for searching. Moreover, this approach ensures security and privacy both in patient’s side and the doctor’s side. Also, we propose another approach for developing a key management system, which will effectively handle the allocation of encryption and decryption keys for all the people who are handling the sensitive medical data of the patients. The experimental results show that our proposed model of cryptosystem ensures that the data has been stored and retrieved with higher security with relatively optimized searching time. Moreover, this approach is very efficient in terms of space complexity, search indexing and secret access of data comparing with many of the existing algorithms.

随着互联网，医学领域的更大发展，有关患者及其检查结果的所有机密信息都保存在世界各地的任何远程服务器中。由于在处理与患者相关的数据时要保持机密性，因此仅由授权人员处理数据非常重要。在常规的数据存储方法中，通常在患者侧对数据进行加密，然后将其安全地保存在远程云服务器中。因此，患者有权决定其数据的可见性，因此成为数据所有者。但是，这种方法的主要缺点是对于需要访问医疗数据的医生而言，其数据可用性受到限制。在本文中，我们提出了两个动态高效的密码系统，用于安全存储和访问医疗数据。第一种算法利用了高安全加密标准方案，该方案具有使存储在远程云中的加密数据可用于搜索的优点。而且，这种方法确保了患者侧和医生侧的安全性和私密性。此外，我们提出了另一种开发密钥管理系统的方法，该系统将有效地为所有处理患者敏感医疗数据的人员处理加密和解密密钥的分配。实验结果表明，我们提出的密码系统模型可以确保以相对最佳的搜索时间以更高的安全性存储和检索数据。此外，