Here it is -- RSA encryption written in assembler. FREEWARE!

You may use this sources in any vx-related (or destructive) purposes.

Z0MBiE
http://z0mbie.cjb.net

to encrypt/decrypt data just call rsa_main(...). see EXAMPLE

FEATURES:
- code is fucking slow
- but it works
- no overflow & other checking
- fixed length of bignumbers (see BN_xxx consts)
- to create your RSA keys see howkey.zip/scrgrab.zip/txt2den.zip

Q> how many data bytes may be encrypted per one call to rsa_main() ?
A> when encrypting, your data is represented as a big number,
and it should be less than m, so accept max data block size
equal to ((rsa_bit/8)-1) bytes.

Source