Can you prevent a block of memory from being swapped?

Question

I'm wondering if there's a way to "lock" a section of memory in Java so that it will not be written out to the swap file by the OS.
Let's say you're writing a client application that will connect to a server, and allow the user (after authentication, of course) to download sensitive information to the client machine and view it. Because the client machine may be in an unsecure environment (i.e. public library terminal, cybercafe, etc), it is desirable to ensure that no trace of the information remains, even in the swap file. The data in question is largely text, so it wouldn't be more than a few hundred KB, therefore I can't imagine it would be a problem to reserve this memory (i.e. it's not like we're starving out other applications running on the same client machine by reserving ALL physical memory).
Basically I'm looking for something in the API that lets me say to the OS: "don't swap out this block of memory, no matter what". Is there a way to do this?
I found this in the bug database but it doesn't sound entirely like what I'm looking for (and it's marked as "will not fix" anyway):
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4852696

Answer 1

The simple answer is "no".
This is a valid concern about the use of crypto libraries in Java.
Because Java has garbage collection, and can copy anything to any memory region during garbage collection, in practice the crypto library writers choose not to bother about non-swapped memory.
Implementing non-swapped memory in some operating systems like Windows is not a simple task: I believe that in Windows you need to write a device driver and a Windows Service, like the "Protected Storage Service" that you can find in Windows. The "Protected Storage" is not very used in Windows - it implements only the CryptEncryptData and CryptDecryptData APIs. The real crypto work is done in normal memory, if you check the CryptoAPI Providers that come with Windows.