The Inforarium was, according to the Eleventh Doctor, "the greatest source of illicit information in recorded history". This information was stored in twelve levels of reality, making it near-impossible to hack.
It contained information on the Doctor, which was sold to the Daleks, the Cybermen and the Sontarans, which the Doctor took issue with. He therefore "memory-proofed" the content, adapting Silence biology to his own needs, and making anyone who learned anything of him forget soon after. (HOMEVID: The Inforarium)