The secret key of a user and the ciphertext are dependent upon attributes (e.g. their email address, the country in which they live, or the kind of subscription they have).
Identity-based encryption was first proposed in 1984 by Adi Shamir,[3] without a specific solution or proof.
[5] Melissa Chase and other researchers have further proposed attribute-based encryption with multiple authorities who jointly generate users' private keys.
However, CP-ABE uses access trees to encrypt data and users' secret keys are generated over a set of attributes.
[15] Attribute-based encryption methods are also widely employed in vector-driven search engine interfaces.
This above solution has the following problems: A manuscript of Ari Juels and Michael Szydlo[17] dated 2004 proposed a different, non-collusion-resistant notion of attribute-based encryption.