RSA Cryptography

Hi,

I wrote a little cryptography module.  It implemented a (theoretically) fully secure RSA cryptosystem.

This turned out to be harder than anticipated.  In addition to jogging my memory of RSA, implementing it in Java is a nightmare (exercise of actual real programming).

It turns out that there are two different APIs for this.  The one most directly implemented by Java has a bug that prevents it from working except when writing to a file.  The second is also too buggy to use.

So, I decided to write my own implementation.  It turns out that there are a number of (buggy) Java implementations.  These fail in a number of cases, (usually when a message is too long).  Obviously, real RSA doesn't crash.  I ended up basing my solution on an existing RSA implementation and then rewriting half of it to actually work.

In the process, I also tried compressing the RSA output stream.  It turns out that the Java "Inflate" class has a bug that causes it to hang on the general kind of data that can be produced by compressing an RSA stream.

I can't really do anything about that, because if I were to try to fix all the bugs in the JRE, I should at least get paid--and anyway, at this time, there are more pressing matters, such as serialization, updates concerning which should appear on the next post.

Ian