improve if/elif chain, add some comments
improve if/elif chain, add some comments

Hasimir/cryptography,sholsapp/cryptography,kimvais/cryptography,kimvais/cryptography,kimvais/cryptography,sholsapp/cryptography,sholsapp/cryptography,sholsapp/cryptography,skeuomorf/cryptography,skeuomorf/cryptography,Hasimir/cryptography,skeuomorf/cryptography,kimvais/cryptography,Ayrx/cryptography,Hasimir/cryptography,skeuomorf/cryptography,Hasimir/cryptography,Ayrx/cryptography,Ayrx/cryptography,Ayrx/cryptography