PocketBlock is a visual syntax for cryptographic engineering, for kids, for everyone. It's purpose is to bridge the gap between classical and modern cryptography, by capturing the complexities of the latter in a form as easy-to-grasp as the former.

The first entry in the PocketBlock family is Pockenacci, an authenticated encryption scheme based on a block cipher (SPN-style, or Substitution-Permutation Network), featuring a Fibonacci-style key schedule, two P-boxes (Permutation boxes), and two S-boxes (Substitution boxes), followed by a MAC (Message Authentication Code).