LOL - I asked Google about The Cathars
"1. Most Adherents Were Illiterate
The vast majority of Cathar believers were rural peasants, weavers, and farmers. Written materials were rare luxury items. Complex cryptographic ciphers would have been completely useless for an underground movement that relied on spoken word, preaching, and secret meetings in homes or cave"
So not the best start.... that, and they were all dead by 1321
"1. Most Adherents Were Illiterate
The vast majority of Cathar believers were rural peasants, weavers, and farmers. Written materials were rare luxury items. Complex cryptographic ciphers would have been completely useless for an underground movement that relied on spoken word, preaching, and secret meetings in homes or cave"
So not the best start.... that, and they were all dead by 1321