Does the SHA1PRNG algorithm for SecureRandom use /dev/random for entropy?

Question

I tried looking for this in the javadocs and online but couldn\'t find a definitive answer. The answer by Dan Dyer in

How to solve performance problem with Java SecureR

Answer 1

No, in the default Oracle implementation it uses system resources, unless you seed it before calling nextBytes(). From the Sun/Oracle documentation of SecureRandom:

The SecureRandom implementation attempts to completely randomize the internal state of the generator itself unless the caller follows the call to a getInstance method with a call to the setSeed method:

 SecureRandom random = SecureRandom.getInstance("SHA1PRNG");
 random.setSeed(seed);