Computing the quantile of a massive data stream has been a crucial task in networking and data management. However, existing solutions assume a centralized model where one data owner has access to all data. In this paper, we put forward a study of secure quantile aggregation betweenprivatedata streams, where data streams owned by different parties would like to obtain a quantile of the union of their data without revealing anything else about their inputs. To this end, we designed efficient cryptographic protocols that are secure in the semi-honest setting as well as the malicious setting. By incorporating differential privacy, we further improve the efficiency by 1.1× to 73.1×. We implemented our protocol, which shows practical efficiency to aggregate real-world data streams efficiently.

MOTIVATION: The traditional reads per million normalization method is inappropriate for the evaluation of ChIP-seq data when treatments or mutations have global effects. Changes in global levels of histone modifications can be detected with exogenous reference spike-in controls. However, most ChIP-seq studies overlook the normalization that must be corrected with spike-in. A method that retrospectively renormalizes datasets without spike-in is lacking. RESULTS: ChIPseqSpikeInFree is a novel ChIP-seq normalization method to effectively determine scaling factors for samples across various conditions and treatments, which does not rely on exogenous spike-in chromatin or peak detection to reveal global changes in histone modification occupancy. Application of ChIPseqSpikeInFree on five datasets demonstrates that this in silico approach reveals a similar magnitude of global changes as the spike-in method does. AVAILABILITY AND IMPLEMENTATION: St. Jude Cloud (https://pecan.stjude.cloud/permalink/spikefree) and St. Jude Github ( https://github.com/stjude/ChIPseqSpikeInFree). SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Data transmission exists in almost all the Internet-based applications, while few of them consider the property of nonrepudiation as part of data security. If a data transmission scheme is performed without the endorsement of a trusted third party (TTP) or a central server, it is easy to raise disputes while transmitting valuable data, especially digital goods, because a dishonest participant can deny the fact of particular data transmission instance. The above problem can be solved by signing and encrypting. However, digital signature schemes usually assume public key infrastructure (PKI), increasing the burden on certificate management and are not suitable for distributed networks without TTP such as blockchain. To solve the above problems, we propose two new schemes for nonrepudiation data transmission based on blockchain (we call it BNRDT): one for short message transmission and the other for large file transmission. In BNRDT schemes, nonrepudiation evidence of data transmission is generated and stored on the blockchain to satisfy both the properties of nonrepudiation (including nonrepudiation of origin and nonrepudiation of receipt) and data confidentiality. We implement and test the schemes on Hyperledger Fabric. The experimental results show that the proposed schemes can provide appealing performance.