There definitely exists a "magic number" which allows whoever knows the magic number along with 32 bytes of the PRNG output to completely predict the rest of the output. The algorithm designer may (or may not) have had a specific magic number in mind when designing this algorithm. If so, it's a backdoor. If not, it's not (but there's no way to know for sure). Consider also that this algorithm is about a thousand times slower than other PRNGs and produces random numbers with a slight bias, making it an extremely poor choice even if it doesn't have a backdoor. The only reason I can think of for the NSA to endorse such an obviously flawed algorithm is that it's the only one they were able to get a backdoor into. What other explanation is there?