The main idea with the challenge-response type of authentication protocol is that the challenge sent by the server is used only once (referred to as a cryptographic nonce, which means “number used once”).

But finally we came to a river with hundreds of boats upon it, and there was a magnificent bridge, and on the other bank was a roaring city, and through the fog the rain came down thick as the tears of the angels. That 's London, said I.

'Tis the secret Of nature, naturized 'gainst all infections, Cures all diseases, coming of all causes

Auxiliary tests include solutions for deficiencies of data partitioning methods (e.g. the use of masks to remove clean bias and hybrid methods to remove sidelobes from sources left undeconvolved), the effect of sources not at pixel centers and the consequences of various other numerical approximations within software implementations.