[Balin999]

Hm that is rather embarassing for I have thought that Sauron himself made the rings of the Nine. How silly!
But, as I have researched in the Silmarillion, Sauron was the one who helped them creating the rings, meaning he supported them with knowledge, while secretly crafting his own ring.

Ah, here it says (please mind that I only have the German version of the Silmarillion, so I may not cite 100% correctly):

"But Sauron gathered the remaining Rings of Power, and he gave them to the other races of middle-earth, hoping to rule all who were longing for power [...] in the end.
Seven he gave to the dwarfes, [...] but nine he gave to men, [...]
And all of the rings he ruled he could corrupt easily, because he had helped with their creation."

So, well, it is definitely not true that he had created the rings, but he had spoiled them before he gave them to men and dwarfes, so my theory about the Mouth of Sauron can still partly be true.