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<a name="Representation-of-Binary-Data"></a>
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<p>
Next: <a href="Input-and-Output.html#Input-and-Output" accesskey="n" rel="next">Input and Output</a>, Previous: <a href="Procedure-Names.html#Procedure-Names" accesskey="p" rel="prev">Procedure Names</a>, Up: <a href="Guile-API-Conventions.html#Guile-API-Conventions" accesskey="u" rel="up">Guile API Conventions</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Procedure-Index.html#Procedure-Index" title="Index" rel="index">Index</a>]</p>
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<hr>
<a name="Representation-of-Binary-Data-1"></a>
<h3 class="section">3.3 Representation of Binary Data</h3>
<p>Many procedures operate on binary data. For instance,
<code>pkcs3-import-dh-parameters</code> expects binary data as input.
</p>
<a name="index-SRFI_002d4"></a>
<a name="index-homogeneous-vector"></a>
<p>Binary data is represented on the Scheme side using SRFI-4 homogeneous
vectors (see <a href="http://www.gnu.org/software/guile/manual/html_node/SRFI_002d4.html#SRFI_002d4">SRFI-4</a> in <cite>The GNU Guile Reference Manual</cite>).
Although any type of homogeneous vector may be used, <code>u8vector</code>s
(i.e., vectors of bytes) are highly recommended.
</p>
<p>As an example, generating and then exporting Diffie-Hellman parameters
in the PEM format can be done as follows:
</p>
<a name="index-make_002ddh_002dparameters"></a>
<a name="index-pkcs3_002dexport_002ddh_002dparameters"></a>
<a name="index-x509_002dcertificate_002dformat_002fpem"></a>
<div class="example">
<pre class="example">(let* ((dh (make-dh-parameters 1024))
(pem (pkcs3-export-dh-parameters dh
x509-certificate-format/pem)))
(call-with-output-file "some-file.pem"
(lambda (port)
(uniform-vector-write pem port))))
</pre></div>
<p>For an example of OpenPGP key import from a file, see <a href="Importing-OpenPGP-Keys-Guile-Example.html#Importing-OpenPGP-Keys-Guile-Example">Importing OpenPGP Keys Guile Example</a>.
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