Blockchain technology is increasingly being adopted as a trusted platform to support business functions including trusted and verifiable transactions, tracking, and validation. However, most business use-cases require privacy and confidentiality for data and transactions. As a result, businesses are forced to choose private blockchain solutions and unable to take full advantage of the capabilities, benefits and infrastructure of public blockchain systems. To address this issue, we present an Attribute-Based Encryption (ABE) security solution built on a private-over-public (PoP) blockchain approach. The policy based distributed operation of ABE conforms well to the blockchain concept. The cross-chain PoP approach provides the benefits from both public blockchains and private blockchains. Businesses will be able to restrict access, maintain privacy, and improve performance while still being able to leverage the distributed trust of public blockchains. This paper present the ABE-based security framework and protocol for securing data, transactions as well as smart contracts. Security analysis and performance evaluation show the proposed solution to be effective, efficient and practical. It can greatly reduce the cost and complexity for businesses compared to running isolated private blockchain solutions.