Functional encryption (FE) ciphertext is transformed into partially-decrypted (PD) ciphertext. The PD ciphertext has a shorter bit length than the FE ciphertext, or the decryption time of the PD ciphertext is less than the decryption time of the FE ciphertext. The FE ciphertext can be an attribute-based encryption ciphertext. The transformation can be performed with a transformation key generated by an authority with a master key or by a user with a decryption key. The transformation can also be performed, without a transformation key, based on unencrypted components of the FE ciphertext and on auxiliary information associated with the unencrypted components of the FE ciphertext. The PD ciphertext can require less transmission time across a network than the FE ciphertext. The PD ciphertext can require less time to decrypt than the FE ciphertext, particularly when the computational resources performing the decryption are limited.