RandomIdGenerator is not thread safe

[serac]

IdGenerators are intended to be thread safe, yet this component is not due to the use of org.bouncycastle.crypto.prng.drbg.HashSP800DRBG, which is not thread safe. Errors like the following may arise under moderate concurrency:

Caused by: java.lang.ArrayIndexOutOfBoundsException: 4
    at org.bouncycastle.crypto.digests.GeneralDigest.update(Unknown Source)
    at org.bouncycastle.crypto.digests.GeneralDigest.update(Unknown Source)
    at org.bouncycastle.crypto.prng.drbg.HashSP800DRBG.doHash(Unknown Source)
    at org.bouncycastle.crypto.prng.drbg.HashSP800DRBG.hashgen(Unknown Source)
    at org.bouncycastle.crypto.prng.drbg.HashSP800DRBG.generate(Unknown Source)
    at org.cryptacular.generator.RandomIdGenerator.generate(RandomIdGenerator.java:69)

[serac]

Fixed in b112a9b.