Package cipherio allows to use block ciphers with io.Reader and io.Writer. Golang already provides io.Reader and io.Writer implementations for cipher.Stream, but not for cipher.BlockMode (such as AES-CBC). The purpose of this package is to fill the gap. Block ciphers require data size to be a multiple of the block size. The io.Reader and io.Writer implementations found here can either enforce this requirement or automatically apply a user-defined padding. This package has been written with performance in mind: buffering and copies are avoided as much as possible.