Can a striped lock be used to synchronize a map?

Question

I don't know why I can't get my head around this question.

I see examples on the internet where people talk about using striped locking to synchronize a map. The idea is to use multiple locks to allow for more concurrency, while retaining correctness. But is an approach like this actually correct?

I believe that the idea is to have one lock per bucket, the same thing that ConcurrentHashMap does under the hood, but how can one achieve such a feat given the fact the the mapping key -> bucket is an internal Map implementation detail, and is not actually possible to match it from the outside of the Map?

Take this example:

public void concurrentMethod(String key) {
    val lock = stripedLock.get(key))
    lock.lock()
    // do work on map[key]
    lock.unlock()
}

there's no guarantee that stripedLocks.get(key) will return the same lock for 2 keys that will end up in the same bucket. So, as far as I can tell, this is not correct and the synchronization doesn't actually work.

Is my reasoning wrong here? Can an approach like this lead to correct synchronization?