Also, the government tends to separate out makers (manufacturers) from sellers (vendors), though they could be the same entity. Someone may be able to sell software (say on the Google Play Store or Steam or Apple's App Store), without restrictions. But the makers of the software would be subject to this law if their applications permitted or enabled encrypted communication.
This is likely to make it less obviously a 1st-amendment issue.
Saying "authors of software" makes it a fairly obvious restraint of speech.