Implement randomized verify of "Chosen-Ciphertext Secure Attribute-Based Key Encapsulation and Encryption without Random Oracle" KEM

(This issue has been imported from the Gitlab repository because it seems to not have been addressed yet)

Note: Not sure which KEM is meant with this so might be relevant to Predenc and not Craco

Original Text (Issue 59)

The verification should be randomized for better performance. See paper for details (and ask [at]utyf if necessary)