[rurban]

See also http://perl11.org/blog/seed.html "The dangerous SipHash myth"

It's technically impossible to declare a hash function used in hash table secure, a countermeasure against DoS attacks. djb made a bad mistake here. You always get seed exposure somehow. It is independent on the hash function. You can always brute-force it.

So java is right. The only countermeasure against collision attacks are fixes in the collision resolution. Adding stronger hash functions only makes the table slower, but not secure. And lot's of prominent hash tables are insecure, since they drank djb's cool aid.