pub fn decrypt(
key: &[u8; 128],
iv: &[u8; 48],
dst: &mut [u8],
src: &[u8]
) -> Result<(), LionessError>
decrypt a block
key - a key
iv - an IV
dst - a destination mutable byte slice
src - a source reference to a byte slice of data to decrypt
LionessError::BlockSizeError - returned if block size is too small