class type scheme = object ... end
Generic interface of a padding scheme.
method pad : string -> int -> unit
pad str used is called with a buffer string
str
containing valid input data at positions
0, ..., used-1.
The
pad method must write padding characters in positions
used to
String.length str - 1. It is guaranteed that
used < String.length str, so that at least one character of
padding must be added. The padding scheme must be unambiguous
in the following sense: from
buf after padding, it must be
possible to determine
used unambiguously. (This is what
method
Cryptokit.Padding.scheme.strip does.)
method strip : string -> int
This is the converse of the pad operation: from a padded
string buf as built by method pad, strip buf determines
and returns the starting position of the padding data,
or equivalently the length of valid, non-padded input data
in buf. This method must raise Error Bad_padding if
buf does not have the format of a padded block as produced
by pad.