Java Security

Hi all,

I have a RSA ciphertext generated by OpenSSL (on a GNU/Linux i386) that is saved to a file.

I then opened the file in Java, read the bytes and attempt to decrypt it. Initially, I get errors like padding and stuff, so I've set the padding on both ends to be the same.

Now, I think my problem is this: the ciphertext bytes are written to the file as C's `unsigned char`. However, Java's `byte` representation is not the same as C's `unsigned char`.

The way I am reading the file is this:

File -> FileInputStream -> DataInputStream

I have used DataInputStream.read() and DataInputStream.readUnsignedByte().

Now both of these upcasts the `unsigned char` of the file to a Java's `int`. The problem is the javax.crypto.Crypto related classes operate on `byte`. And the ciphertext needs to be parsed byte by byte.

So what I am asking is, how do I correctly read and decrypt RSA ciphertext that is generated by a C program, using OpenSSL and saved as `unsigned char`?

I've seen many examples of this C's `unsigned char` to Java's `byte` problem, but they mainly related to Strings encoding and not actual bytes of ciphertext.

Thanks.

Hon Hwang.

BTW, I've tried using the Integer class.