@c acl_blockcipher.texi
@section Block ciphers
-@subsection What a block cipher does
- A block cipher is a algorithm which turn an input of fixed length into an
+ A block cipher is a algorithm which turns an input of fixed length into an
output of the same length (enciphering or encrypting). The transformation is
specified by a key which has to be of a fixed length, or a length of a given
set or range.