Tunable Security for Deployable Data Outsourcing

Security mechanisms like encryption negatively affect other software quality characteristics like efficiency. To cope with such trade-offs, it is preferable to build approaches that allow to tune the trade-offs after the implementation and design phase. This book introduces a methodology that can be used to build such tunable approaches. The book shows how the proposed methodology can be applied in the domains of database outsourcing, identity management, and credential management

Integrity Coded Databases: Ensuring Correctness and Freshness of Outsourced Databases

In recent years, cloud storage has become an inexpensive and convenient option for individuals and businesses to store and retrieve information. The cloud releases the data owner from the financial burden of hiring professionals to create, update and maintain local databases. The advancements in the field of networking and the growing need for computing resources for various applications have made cloud computing more demanding. Its positive aspects make the cloud an attractive option for data storage, but this service comes with a cost that it requires the data owner to relinquish control of their information to the cloud service provider. So, there remains the possibility for malicious insider attacks on the data that may involve addition, omission, or manipulation of data. This paper presents a novel Integrity Coded Database (ICDB) approach for ensuring data correctness and freshness in the cloud. Various options for verifying the integrity of queried data in different granularities are provided, such as the coarse-grained integrity protection for the entire returned dataset or a more fine-grained integrity protection down to each tuple or even each attribute. ICDB allows data owners to insert integrity codes into a database, outsource the database to the cloud, run queries against the cloud database server, and verify that the queried information from the cloud is both correct and fresh. An ICDB prototype has been developed in order to benchmark several ICDB schemes to evaluate their performance

CryptDB: A Practical Encrypted Relational DBMS

CryptDB is a DBMS that provides provable and practical privacy in the face of a compromised database server or curious database administrators. CryptDB works by executing SQL queries over encrypted data. At its core are three novel ideas: an SQL-aware encryption strategy that maps SQL operations to encryption schemes, adjustable query-based encryption which allows CryptDB to adjust the encryption level of each data item based on user queries, and onion encryption to efficiently change data encryption levels. CryptDB only empowers the server to execute queries that the users requested, and achieves maximum privacy given the mix of queries issued by the users. The database server fully evaluates queries on encrypted data and sends the result back to the client for final decryption; client machines do not perform any query processing and client-side applications run unchanged. Our evaluation shows that CryptDB has modest overhead: on the TPC-C benchmark on Postgres, CryptDB reduces throughput by 27% compared to regular Postgres. Importantly, CryptDB does not change the innards of existing DBMSs: we realized the implementation of CryptDB using client-side query rewriting/encrypting, user-defined functions, and server-side tables for public key information. As such, CryptDB is portable; porting CryptDB to MySQL required changing 86 lines of code, mostly at the connectivity layer

Secure data replication over untrusted hosts

In the Internet age, data replication is a popular technique for achieving fault tolerance and improved performance. With the advent of content delivery networks, it is becoming more and more frequent that data content is placed on hosts that are not directly controlled by the content owner, and because of this, security mechanisms to protect data integrity are necessary. In this paper we present a system architecture that allows arbitrary queries to be supported on data content replicated on untrusted servers. To prevent these servers from returning erroneous answers to client queries, we make use of a small number of trusted hosts that randomly check these answers and take corrective action whenever necessary. Additionally, our system employs an audit mechanism that guarantees that any untrusted server acting maliciously will eventually be detected and excluded from the system

CryptDB: Protecting confidentiality with encrypted query processing

Online applications are vulnerable to theft of sensitive information because adversaries can exploit software bugs to gain access to private data, and because curious or malicious administrators may capture and leak data. CryptDB is a system that provides practical and provable confidentiality in the face of these attacks for applications backed by SQL databases. It works by executing SQL queries over encrypted data using a collection of efficient SQL-aware encryption schemes. CryptDB can also chain encryption keys to user passwords, so that a data item can be decrypted only by using the password of one of the users with access to that data. As a result, a database administrator never gets access to decrypted data, and even if all servers are compromised, an adversary cannot decrypt the data of any user who is not logged in. An analysis of a trace of 126 million SQL queries from a production MySQL server shows that CryptDB can support operations over encrypted data for 99.5% of the 128,840 columns seen in the trace. Our evaluation shows that CryptDB has low overhead, reducing throughput by 14.5% for phpBB, a web forum application, and by 26% for queries from TPC-C, compared to unmodified MySQL. Chaining encryption keys to user passwords requires 11--13 unique schema annotations to secure more than 20 sensitive fields and 2--7 lines of source code changes for three multi-user web applications.National Science Foundation (U.S.) (CNS-0716273)National Science Foundation (U.S.) (IIS-1065219

Scalable Verification for Outsourced Dynamic Databases

Query answers from servers operated by third parties need to be verified, as the third parties may not be trusted or their servers may be compromised. Most of the existing authentication methods construct validity proofs based on the Merkle hash tree (MHT). The MHT, however, imposes severe concurrency constraints that slow down data updates. We introduce a protocol, built upon signature aggregation, for checking the authenticity, completeness and freshness of query answers. The protocol offers the important property of allowing new data to be disseminated immediately, while ensuring that outdated values beyond a pre-set age can be detected. We also propose an efficient verification technique for ad-hoc equijoins, for which no practical solution existed. In addition, for servers that need to process heavy query workloads, we introduce a mechanism that significantly reduces the proof construction time by caching just a small number of strategically chosen aggregate signatures. The efficiency and efficacy of our proposed mechanisms are confirmed through extensive experiments. 1

Securing Cloud File Systems using Shielded Execution

Cloud file systems offer organizations a scalable and reliable file storage solution. However, cloud file systems have become prime targets for adversaries, and traditional designs are not equipped to protect organizations against the myriad of attacks that may be initiated by a malicious cloud provider, co-tenant, or end-client. Recently proposed designs leveraging cryptographic techniques and trusted execution environments (TEEs) still force organizations to make undesirable trade-offs, consequently leading to either security, functional, or performance limitations. In this paper, we introduce TFS, a cloud file system that leverages the security capabilities provided by TEEs to bootstrap new security protocols that meet real-world security, functional, and performance requirements. Through extensive security and performance analyses, we show that TFS can ensure stronger security guarantees while still providing practical utility and performance w.r.t. state-of-the-art systems; compared to the widely-used NFS, TFS achieves up to 2.1X speedups across micro-benchmarks and incurs <1X overhead for most macro-benchmark workloads. TFS demonstrates that organizations need not sacrifice file system security to embrace the functional and performance advantages of outsourcing