Cyprianus is also known as the Black Book, and is the textbook of the Black School at Wittenburg, the book from which a witch or sorcerer gets his spells.
The Black School at Wittenburg was purportedly a place in Germany where one went to learn the black arts.
Cyprianus, M. L. , Clavis Inferni sive magia alba et nigra approbata Metratona. Page 4. Library reference no.: Archives and Manuscripts MS.2000
“The actual stories told of Cyprianus in Scandinavia often made no reference to St. Cyprian. Some made Cyprianus into a typical Faust figure; some said that Cyprianus was a wicked Norwegian or Dane who learned magic through his dealings with the Devil; one version makes Cyprianus so evil that the Devil threw him out of Hell; Cyprianus wrote the text to have his revenge. A different and strongly contradictory version explains that Cyprianus was a student who discovered he was attending a diabolical “black school,” and wrote the text to explain how to undo all the witchcraft he learned there.”Pasted from <http://en.wikipedia.org/wiki/Cyprianus>