On Efficient Ciphertext-Policy Attribute Based Encryption and Broadcast Encryption
Ciphertext Policy Attribute Based Encryption (CP-ABE) enforces an expressive data access policy, which consists of a number of attributes connected by logical gates. Only those decryptors whose attributes satisfy the data access policy can decrypt the ciphertext. CP-ABE is very appealing since the ciphertext and data access policies are integrated together in a natural and effective way. However, all existing CP-ABE schemes incur very large ciphertext size, which increases linearly with respect to the number of attributes in the access policy. Large ciphertext prevents CP-ABE from being adopted in the communication constrained environments.