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Summary Ciphertext‐policy attribute‐based encryption (CP‐ABE) is the recommended best practice for outsourced big data access control in the cloud environment. However, most of the existing CP‐ABE schemes do not address the issue of tracing and revoking the malicious user who leaks the secret key for profit, which in turn reduces the security of the CP‐ABE schemes. In this paper, we propose a dynamic traceable CP‐ABE with revocation (DTCP‐ABE) for outsourced big data in cloud storage. DTCP‐ABE scheme dynamically traces who decrypts the ciphertext during the outsourced decryption process, which helps to find the malicious user who leaks the secret key. Our scheme also automatically revokes the malicious users once they are identified. We prove that our scheme is secure against chosen‐plaintext, secret key forging, user collision, and proxy attacks. Furthermore, our scheme also achieves backward revocation security. Performance evaluation proves that our DTCP‐ABE scheme is efficient than other existing schemes.

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Ciphertext-policy attribute-based encryption (CP-ABE) schemes are an appropriate cryptographic technique to enable privacy along with access control in the cloud, but the existing CP-ABE schemes do not directly apply for big data because they have the issue of long ciphertext and long secret key size (LC-LS). To address LC-LS, the constant size ciphertext and secret key (CSC-S) schemes proposed. However, the existing CSC-S schemes suffer from the key escrow security issue and efficiency issue. To address both simultaneously, the authors propose an efficient escrow-free CP-ABE with constant size ciphertext and secret key (EEF-CPABE) for big data storage in the Cloud. The EEF-CPABE scheme reduces the encryption and decryption computation overhead by designing CSC-S. Further, the data owner generates the decryption global key to decrypt the data along with user secret key which solves the key escrow issue. Security and performance analysis demonstrate that the EEF-CPABE scheme resists against authority, and chosen plain-text attacks and more efficient than CSC-S schemes.