IDEA encryption

[Derek Atkins]

> The copy of the source for idea (unix) that I have specify's a user key 
> length of 8 bytes, but allows this to be increased to something larger. 
> Will increasing the user keylength improve the overall security? 

Umm, I think you are confused.  First, IDEA has a keysize of 16 bytes,
not 8.  Second, it cannot be easily changed.  Sure, your code probably
has a #define for the keysize, but that is just to describe the magic
number, not to make it easy to change it. Increasing the keylength of
IDEA, without changing anything else, will probably _NOT_ make it more
secure.

> Last thing -- how secure is unix "rm"?  If something is rm'd, is it 
> really really gone? 

Well, it depends on what you mean by "really really gone".  All RM
does is remove the link from the directory entry to the file inode on
disk.  If the inode refcount reahes zero, then the disk blocks are
marked as free.  However the data in those blocks remain on disk until
another file writes over them.

It is theoretically possible to write a program to "unrm" a file.

-derek