class Mail::Encodings::Base64

per input byte.
Base64 encoding handles binary content at the cost of 4 output bytes

def self.can_encode?(enc) 

def self.can_encode?(enc)
  true
end

def self.compatible_input?(str)

SMTP line length limits.
Ruby Base64 inserts newlines automatically, so it doesn't exceed 
def self.compatible_input?(str)
  true
end

def self.cost(str)

3 bytes in -> 4 bytes out 
def self.cost(str)
  4.0 / 3
end

def self.decode(str) 

def self.decode(str)
  Utilities.decode_base64(str)
end

def self.encode(str) 

def self.encode(str)
  ::Mail::Utilities.binary_unsafe_to_crlf(Utilities.encode_base64(str))
end