This legislation says things such as the following:
"A person commits an offense if the person intentionally or knowingly manufactures, assembles, imports into the state, exports out of the state, distributes, advertises, sells, or leases, or offers for sale or lease a communication device with an intent to conceal from a communication service
provider, or from any lawful authority, the existence or place of origin or destination of any communication, or plans or instructions for assembling or manufacturing a communication device or unauthorized access device, with the knowledge that another person intends to use the plans or instructions for an unlawful purpose."
In other words, not only is encryption potentially criminal, so are firewalls.
Legislation in this vein is being proposed in the following states:
AK, CO, FL, GA, MA, SC, TN, TX