  The quest for a cryptographically secure pseudorandom bit generator (PRBG)
was initiated long ago, and for a long time the proposed pseudorandom
generators were very slow. More recently some "provably secure" PRBG capable to
achieve a throughput rate greater than 1Mbit/sec. We noticed, anyway, the
absence of Java implementations of such PRBGs, provably due to poor expected
values for throughput rate. In the present paper we show that it is quite easy
to write down Java implementations for them, achieving a throughput rae into
range $0,5\div 7$ Mbit/sec on very common mobile low-end devices.
