add a package description

qpp.go

@@ -1,3 +1,17 @@
+// Package qpp implements Quantum permutation pad
+//
+// Quantum permutation pad or QPP is a quantum-safe symmetric cryptographic
+// algorithm proposed by Kuang and Bettenburg in 2020. The theoretical
+// foundation of QPP leverages the linear algebraic representations of
+// quantum gates which makes QPP realizable in both, quantum and classical
+// systems. By applying the QPP with 64 of 8-bit permutation gates, holding
+// respective entropy of over 100,000 bits, they accomplished quantum random
+// number distributions digitally over today’s classical internet. The QPP has
+// also been used to create pseudo quantum random numbers and served as a
+// foundation for quantum-safe lightweight block and streaming ciphers.
+//
+// This file implements QPP in 8-qubits, which is compatible with the classical
+// architecture. In 8-qubits, the overall permutation matrix reaches 256!.
 package qpp
 
 import (