Cryptographically speaking, the genie is kind of out of the bottle, since any modern PC, Laptop, or Smartphone is more than capable of easily performing ultra secure encryption that all the super-computers on earth could not break in a million years.
Back in the 90's the U.S. government did go kind of nuts trying to put that genie back in the bottle by forcing everyone to use their backdoored ''Clipper Chip" using the now defunct 80 bit Skipjack Cipher, but these days they seem to have adopted a different tack and instead concentrate on finding (or creating) various sleazy little hacks to subvert otherwise strong crypto.
So far as the Raspberry Pi goes; although it might have some low level cryptographic hardware support for a secure boot loader, and secure WiFi, so do ALL modern PCs, Laptops, Tablets, and Smartphones.
Can Raspbian on the Raspberry Pi be used to do unbreakable encryption? Sure and so can Debian on pretty much any PC, MAC, Laptop, Tablet, or Smartphone. The Raspberry Pi is technically LESS of an offender, since by default, the hardware ships without even having an operating system installed.
These days ANY device with a C compiler or Basic interpreter, could potentially be used to implement unbreakable encryption fairly easily, including tiny pico-processor equipped devices like the Arduino Nano, so of course it's fairly trivial for even the least powerful Raspberry Pi, the Pi Zero, which has several hundred times the raw CPU power and several THOUSAND times as much RAM.
The only way to avoid this would to ban ALL microprocessors, and regress civilization to the stone age.