So, NSA can break 64-bit keys

The WSJ article on Clipper II (The Next Day) was the best one. Particularly this line: "Clint Brooks, a technical advisor with the NSA [said] that continued [64-bit] limits [on key length] were needed because officials were "uneasy" about the possibility that software could be altered so that the key would no longer be accessible to law-enforcement officials." This must mean that the Feds figure that by the time this turkey gets around to actually flying (sometime well after the Clinton administration), 64-bit keys will be (are) vulnerable. I guess this means no source code. Are there any software encryption systems that can't be modified after the fact? DCF "Course, the source code could be released after key escrow has occured."