Tiger's Code — Betty J. Vaughn

Quint Cord is an unlikely spy. With sufficient family money so that he never needs to work, he could have spent his life idling on a beach chasing women. But from the moment he discovers famous codes of the past in a university class, he is hooked. His unique talent for creating and breaking codes brings him to the attention of the CIA.
A powerful and ambitious politician, who's in cahoots with a Saudi prince, plans to seize the US presidency and throw the western world into turmoil. Quint flees the country only to stay one step ahead of a foe determined to kill him before he can break the code.
Clue by clue, Quint begins to zero in on his target but can he stop him in time?