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<link title="Cryptokit" rel="Chapter" href="Cryptokit.html"><title>Cryptokit.Padding.scheme</title>
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<center><h1>Class type <a href="type_Cryptokit.Padding.scheme.html">Cryptokit.Padding.scheme</a></h1></center>
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<pre><span class="keyword">class type</span> <a name="TYPEscheme"></a>scheme = <code class="code">object</code> <a href="Cryptokit.Padding.scheme.html">..</a> <code class="code">end</code></pre>Generic interface of a padding scheme.<br>
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<pre><span class="keyword">method</span> <a name="METHODpad"></a>pad : <code class="type">string -> int -> unit</code></pre><div class="info">
<code class="code">pad str used</code> is called with a buffer string <code class="code">str</code>
containing valid input data at positions <code class="code">0, ..., used-1</code>.
The <code class="code">pad</code> method must write padding characters in positions
<code class="code">used</code> to <code class="code">String.length str - 1</code>. It is guaranteed that
<code class="code">used < String.length str</code>, so that at least one character of
padding must be added. The padding scheme must be unambiguous
in the following sense: from <code class="code">buf</code> after padding, it must be
possible to determine <code class="code">used</code> unambiguously. (This is what
method <a href="Cryptokit.Padding.scheme.html#METHODstrip"><code class="code">Cryptokit.Padding.scheme.strip</code></a> does.)<br>
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<pre><span class="keyword">method</span> <a name="METHODstrip"></a>strip : <code class="type">string -> int</code></pre><div class="info">
This is the converse of the <code class="code">pad</code> operation: from a padded
string <code class="code">buf</code> as built by method <code class="code">pad</code>, <code class="code">strip buf</code> determines
and returns the starting position of the padding data,
or equivalently the length of valid, non-padded input data
in <code class="code">buf</code>. This method must raise <code class="code">Error Bad_padding</code> if
<code class="code">buf</code> does not have the format of a padded block as produced
by <code class="code">pad</code>.<br>
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