Function decrypt_data_v2 

pub fn decrypt_data_v2<'a>(
    buffer: &'a mut [u8],
    auth_key: &AuthKey,
) -> Result<&'a mut [u8], DecryptError>

Decrypt an MTProto 2.0 ciphertext.

buffer must start with key_id || msg_key || ciphertext. On success returns a slice of buffer containing the plaintext.