DRM -- if it had a 7 bit ASCII teletype 'subchannel' type added to it, could
eliminate numbers stations...
Binary files can be transmitted using only 7 bit ASCII chars, preferably
with a little error correction.
There is a LINUX program that can convert binary files into alphanumeric
telegram format, similar to VENONA.

This would be most true if layered AES + modified (A5/1) or Blowfish + (MD5
+ SH1) encryption and digital signatures were supported in some way.

AES (inner layer) : http://en.wikipedia.org/wiki/Rijndael
A5/1 (outer layer) : http://en.wikipedia.org/wiki/A5/1
Blowfish : http://en.wikipedia.org/wiki/Blowfish_(cipher)