Draw from the kernel's CPRNG.
#include <zircon/syscalls.h> void zx_cprng_draw(void* buffer, size_t buffer_size);
zx_cprng_draw() draws random bytes from the kernel CPRNG. This data should
be suitable for cryptographic applications.
Clients that require a large volume of randomness should consider using these bytes to seed a user-space random number generator for better performance. "Large" here would mean a large multiple of ZX_CPRNG_DRAW_MAX_LEN, which is currently 256. As always, test the actual latency of your call site before optimizing.
zx_cprng_draw() terminates the calling process if buffer is not a valid
There are no other error conditions. If its arguments are valid,
zx_cprng_draw() will succeed.