Comment by 1vuio0pswjnm7

"Carrying this speculation a step further, it is possible that the available tools have been compromised either in individual instances or en masse. Even where security products are open-source, adequate security evaluations are difficult to conduct initially and difficult to maintain as the products evolve. Typical users upgrade their software when upgrades or packages are offered, without even thinking of the possibility that they may have been targeted for a Trojan horse."

Whitfield Diffie and Susan Landau, Privacy on the Line: The Politics of Wiretapping and Encryption (MIT Press: Cambridge, 2007), 372

Italics are mine