Maximal SHA-1 Hash Performance Tips in Java

Question

I'm writing a Java library that needs to compute SHA-1 hashes. During a common task, the JVM spends about 70% of its time in sun.security.provider.SHA.implCompress, 10% in java.util.zip.Inflater.inflate, and 2% in sun.security.provider.ByteArrayAccess.b2iBig64. (According to NetBeans profiler.)

I can't seem to get the Google search keywords right to get relevant results. I'm not very familiar with the SHA-1 hash algorithm. How can I get the most performance out of an SHA-1 MessageDigest? Is there a certain chunk size I should be digesting, or multiples of certain sizes I should try?

To answer some questions you're thinking about asking:

• Yes, I'm digesting as I read the files (MessageDigest.update), so bytes are only digested once.
• The SHA-1 digests are being used as checksums, usually for files that need to be zlib/inflated.
• No, I can't use a different hash.
• Yes, I know zlib already uses checksums, but external requirements specify the use of SHA-1 hashes on top of that. I can't come up with a good reason why (+1 if you can) :-)

Answer 1

Maybe you can call out to native code written in C. There must be a ton of super optimized SHA1 libraries available.