Some advanced
encryption algorithms applied to cloud computing increase the protection of privacy. In a practice called
crypto-shredding, encryption keys can be deleted when data is no longer used.
Attribute-based encryption (ABE) Attribute-based encryption is a form of
public-key encryption in which the user's secret key and the ciphertext depend on attributes (e.g., the country the user lives in, or their subscription type). In such systems, access to decryption depends not simply on identity but on attributes. Some of the strengths of ABE are that it bypasses the need for explicit key sharing (as in traditional PKI) and identity-based encryption (IBE). However, ABE suffers from key-redistribution complexity: since decryption keys depend on attributes rather than identities, malicious users might leak attribute information, enabling unauthorized access.
Ciphertext-policy ABE (CP-ABE) In CP-ABE, the encryptor controls the access policy for the ciphertext. The process includes Setup, Encrypt, KeyGen, and Decrypt algorithms; the encryptor defines an access structure that must match a user's attributes before decryption is allowed.
Key-policy ABE (KP-ABE) In KP-ABE, the sender encrypts under a set of attributes, and the user's private key is issued to match a policy describing which ciphertexts they may decrypt. KP-ABE shifts access-control responsibility partially to the key-issuer rather than the encryptor. While it provides flexibility, the policy disclosure may weaken privacy guarantees.
Fully Homomorphic Encryption (FHE) Fully Homomorphic Encryption allows arbitrary computation on ciphertext without decryption. It is emerging as a high-security option for cloud environments, including voting systems. While promising, it remains largely experimental.
Searchable Encryption (SE) Searchable encryption enables secure search on encrypted data. It has symmetric and public-key variants. While it supports functionality over encrypted data, it introduces extra attack surfaces, especially when attribute indexing is involved. ==Compliance==