random

Had one unique case where generating a SecureRandom in Java is very very slow, the thing is that this never happens on a regular VM deployment, and only happens in a Pod deployment in Openshift 4.

This is original sample code that is slow,

    @GetMapping(path = "/secure-random")
    public HashMap secureRandom() {
        SecureRandom secureRandom = new SecureRandom();
        secureRandom.setSeed(secureRandom.generateSeed(24));
        return new HashMap(){{
            put("random-value", String.format("%06d", secureRandom.nextInt(1000000)));
        }};
    }

The reason why it is slow is because SecureRandom is relying on the OS random generator which is relying on noise. And it seems that for our case, we are lacking of noise to make a good entropy therefore we arent able to generate a SecureRandom at all.

Our workaround for this is by using a Pseudo Random Number Generator (PRNG) from Java, and not relying on the OS at all. For this example, im using “SHA1PRNG”.

    @GetMapping(path = "/secure-random-new")
    public HashMap secureRandomNew() throws Exception {
        SecureRandom secureRandom = SecureRandom.getInstance("SHA1PRNG");
        secureRandom.setSeed(secureRandom.generateSeed(24));
        return new HashMap(){{
            put("random-value", String.format("%06d", secureRandom.nextInt(1000000)));
        }};
    }

Hope it helps.