help with encryptor - please?!?!

I've been working on a program for MS-DOS machines that will
encrypt and/or password protect .COM and .EXE files.  The way it works
is this: It encrypts the entire file specified by the user, then it
uses a polymorphic encryptor to encrypt the decryption code for the file 
and put it in a decryption envelope filled with anti-debugging code.  IT
then attaches the entire module/decryption code to the file so that it 
is executed initially when the file is run - at which point it decrypts
the file and does whatever relocation is needed (for .EXE files).  In
the case of a password - it asks for the password, encrypts it and checks
it against the stored version, then if they match it decrypts restoration
code using the password as a key and continues on.  

    I've got it working really well at this point - but my encryption 
algorithms are rather simple.  I'm fairly new in the encryption biz, 
and I was wondering what would be good to use for the file encryption 
algorithm to make it as secure as possible?  Of course - the code to 
decrypt it MUST be present in the file, so if you can bypass the anti-
debugging code it's yours, but the polymorphism makes it difficult to 
do this on more than a case-by-case basis.  Still - I'd like to make
it to where one can't just run a "decrypt-em-all" analysis program on it
and be able to read the included text - but I need a good algorithm 
for it.  Any help/suggestions would REALLY be appreciated.  Oh -
if you are interested in the protection utilities, email me at the
address below - it's freeware.

Thanks a lot,
Michael Ellison
ie63@vaxb.acs.unt.edu

If you wish to encrypt any messages E-mailed to me, please use the 
following key.....
-----BEGIN PGP PUBLIC KEY BLOCK-----
Version: 2.3a

mQCNAixUuYYAAAEEAKNllAee26qGqxJck3Bftdkrz0MUQLABGMZqVem9UW9kjjS+
rMAafauqYTE5/Kdnx+4Asj0Wgfon0YBtRMT0crMcBYNqVp4//RUh7wrxQNvKFeeO
ZGuQp2hyHQqh1FDfWsHG4ldGqIV1YuOXq6oeIDkmbwgf8BRgPcZkwUqsF4b1AAUR
tCpNaWNoYWVsIEEuIEVsbGlzb24gPGllNjNAdmF4Yi5hY3MudW50LmVkdT4=
=0rss
-----END PGP PUBLIC KEY BLOCK-----

Hm.  We seem to have a duplication of effort here.  I am currently working
with s_duck@pinetree.org on the same sort of thing that you describe.
Right now we're having problems fooling DOS with the virtual EXE.  However,
the encryption algorithm used is IDEA -- the same one as PGP uses.

I suggest we pool our efforts and swap ideas/source code.
-- 
PGP 2.3 Key by finger