184 lines
8.0 KiB
HTML
Executable File
184 lines
8.0 KiB
HTML
Executable File
<?xml version="1.0" ?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<title>HMAC</title>
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<meta http-equiv="content-type" content="text/html; charset=utf-8" />
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<link rev="made" href="mailto:root@localhost" />
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</head>
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<body style="background-color: white">
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<!-- INDEX BEGIN -->
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<div name="index">
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<p><a name="__index__"></a></p>
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<ul>
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<li><a href="#name">NAME</a></li>
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<li><a href="#synopsis">SYNOPSIS</a></li>
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<li><a href="#description">DESCRIPTION</a></li>
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<li><a href="#return_values">RETURN VALUES</a></li>
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<li><a href="#conforming_to">CONFORMING TO</a></li>
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<li><a href="#see_also">SEE ALSO</a></li>
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<li><a href="#history">HISTORY</a></li>
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<li><a href="#copyright">COPYRIGHT</a></li>
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</ul>
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<hr name="index" />
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</div>
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<!-- INDEX END -->
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<p>
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</p>
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<hr />
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<h1><a name="name">NAME</a></h1>
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<p>HMAC,
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HMAC_CTX_new,
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HMAC_CTX_reset,
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HMAC_CTX_free,
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HMAC_Init,
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HMAC_Init_ex,
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HMAC_Update,
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HMAC_Final,
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HMAC_CTX_copy,
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HMAC_CTX_set_flags,
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HMAC_CTX_get_md,
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HMAC_size
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- HMAC message authentication code</p>
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<p>
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</p>
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<hr />
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<h1><a name="synopsis">SYNOPSIS</a></h1>
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<pre>
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#include <openssl/hmac.h></pre>
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<p>Deprecated since OpenSSL 3.0, can be hidden entirely by defining
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<strong>OPENSSL_API_COMPAT</strong> with a suitable version value, see
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<em>openssl_user_macros(7)</em>:</p>
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<pre>
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unsigned char *HMAC(const EVP_MD *evp_md, const void *key,
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int key_len, const unsigned char *d, int n,
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unsigned char *md, unsigned int *md_len);</pre>
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<pre>
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HMAC_CTX *HMAC_CTX_new(void);
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int HMAC_CTX_reset(HMAC_CTX *ctx);</pre>
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<pre>
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int HMAC_Init_ex(HMAC_CTX *ctx, const void *key, int key_len,
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const EVP_MD *md, ENGINE *impl);
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int HMAC_Update(HMAC_CTX *ctx, const unsigned char *data, int len);
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int HMAC_Final(HMAC_CTX *ctx, unsigned char *md, unsigned int *len);</pre>
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<pre>
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void HMAC_CTX_free(HMAC_CTX *ctx);</pre>
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<pre>
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int HMAC_CTX_copy(HMAC_CTX *dctx, HMAC_CTX *sctx);
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void HMAC_CTX_set_flags(HMAC_CTX *ctx, unsigned long flags);
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const EVP_MD *HMAC_CTX_get_md(const HMAC_CTX *ctx);</pre>
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<pre>
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size_t HMAC_size(const HMAC_CTX *e);</pre>
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<p>Deprecated since OpenSSL 1.1.0, can be hidden entirely by defining
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<strong>OPENSSL_API_COMPAT</strong> with a suitable version value, see
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<em>openssl_user_macros(7)</em>:</p>
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<pre>
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int HMAC_Init(HMAC_CTX *ctx, const void *key, int key_len,
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const EVP_MD *md);</pre>
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<p>
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</p>
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<hr />
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<h1><a name="description">DESCRIPTION</a></h1>
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<p>All of the functions described on this page are deprecated. Applications should
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instead use <em>EVP_MAC_CTX_new(3)</em>, <em>EVP_MAC_CTX_free(3)</em>, <em>EVP_MAC_init(3)</em>,
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<em>EVP_MAC_update(3)</em> and <em>EVP_MAC_final(3)</em>.</p>
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<p>HMAC is a MAC (message authentication code), i.e. a keyed hash
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function used for message authentication, which is based on a hash
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function.</p>
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<p><code>HMAC()</code> computes the message authentication code of the <strong>n</strong> bytes at
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<strong>d</strong> using the hash function <strong>evp_md</strong> and the key <strong>key</strong> which is
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<strong>key_len</strong> bytes long.</p>
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<p>It places the result in <strong>md</strong> (which must have space for the output of
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the hash function, which is no more than <strong>EVP_MAX_MD_SIZE</strong> bytes).
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If <strong>md</strong> is NULL, the digest is placed in a static array. The size of
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the output is placed in <strong>md_len</strong>, unless it is <strong>NULL</strong>. Note: passing a NULL
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value for <strong>md</strong> to use the static array is not thread safe.</p>
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<p><strong>evp_md</strong> is a message digest such as EVP_sha1(), EVP_ripemd160() etc. HMAC does
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not support variable output length digests such as EVP_shake128() and
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EVP_shake256().</p>
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<p><code>HMAC_CTX_new()</code> creates a new HMAC_CTX in heap memory.</p>
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<p><code>HMAC_CTX_reset()</code> clears an existing <strong>HMAC_CTX</strong> and associated
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resources, making it suitable for new computations as if it was newly
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created with <code>HMAC_CTX_new()</code>.</p>
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<p><code>HMAC_CTX_free()</code> erases the key and other data from the <strong>HMAC_CTX</strong>,
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releases any associated resources and finally frees the <strong>HMAC_CTX</strong>
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itself.</p>
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<p>The following functions may be used if the message is not completely
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stored in memory:</p>
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<p><code>HMAC_Init_ex()</code> initializes or reuses a <strong>HMAC_CTX</strong> structure to use the hash
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function <strong>evp_md</strong> and key <strong>key</strong>. If both are NULL, or if <strong>key</strong> is NULL
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and <strong>evp_md</strong> is the same as the previous call, then the
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existing key is
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reused. <strong>ctx</strong> must have been created with <code>HMAC_CTX_new()</code> before the first use
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of an <strong>HMAC_CTX</strong> in this function.</p>
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<p>If <code>HMAC_Init_ex()</code> is called with <strong>key</strong> NULL and <strong>evp_md</strong> is not the
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same as the previous digest used by <strong>ctx</strong> then an error is returned
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because reuse of an existing key with a different digest is not supported.</p>
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<p><code>HMAC_Init()</code> initializes a <strong>HMAC_CTX</strong> structure to use the hash
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function <strong>evp_md</strong> and the key <strong>key</strong> which is <strong>key_len</strong> bytes
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long.</p>
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<p><code>HMAC_Update()</code> can be called repeatedly with chunks of the message to
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be authenticated (<strong>len</strong> bytes at <strong>data</strong>).</p>
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<p><code>HMAC_Final()</code> places the message authentication code in <strong>md</strong>, which
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must have space for the hash function output.</p>
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<p><code>HMAC_CTX_copy()</code> copies all of the internal state from <strong>sctx</strong> into <strong>dctx</strong>.</p>
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<p><code>HMAC_CTX_set_flags()</code> applies the specified flags to the internal EVP_MD_CTXs.
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These flags have the same meaning as for <em>EVP_MD_CTX_set_flags(3)</em>.</p>
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<p><code>HMAC_CTX_get_md()</code> returns the EVP_MD that has previously been set for the
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supplied HMAC_CTX.</p>
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<p><code>HMAC_size()</code> returns the length in bytes of the underlying hash function output.</p>
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<p>
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</p>
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<hr />
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<h1><a name="return_values">RETURN VALUES</a></h1>
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<p><code>HMAC()</code> returns a pointer to the message authentication code or NULL if
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an error occurred.</p>
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<p><code>HMAC_CTX_new()</code> returns a pointer to a new <strong>HMAC_CTX</strong> on success or
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<strong>NULL</strong> if an error occurred.</p>
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<p><code>HMAC_CTX_reset()</code>, <code>HMAC_Init_ex()</code>, <code>HMAC_Update()</code>, <code>HMAC_Final()</code> and
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<code>HMAC_CTX_copy()</code> return 1 for success or 0 if an error occurred.</p>
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<p><code>HMAC_CTX_get_md()</code> return the EVP_MD previously set for the supplied HMAC_CTX or
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NULL if no EVP_MD has been set.</p>
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<p><code>HMAC_size()</code> returns the length in bytes of the underlying hash function output
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or zero on error.</p>
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<p>
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</p>
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<hr />
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<h1><a name="conforming_to">CONFORMING TO</a></h1>
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<p>RFC 2104</p>
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<p>
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</p>
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<hr />
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<h1><a name="see_also">SEE ALSO</a></h1>
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<p><em>SHA1(3)</em>, <em>evp(7)</em></p>
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<p>
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</p>
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<hr />
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<h1><a name="history">HISTORY</a></h1>
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<p>All of these functions were deprecated in OpenSSL 3.0.</p>
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<p><code>HMAC_CTX_init()</code> was replaced with <code>HMAC_CTX_reset()</code> in OpenSSL 1.1.0.</p>
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<p><code>HMAC_CTX_cleanup()</code> existed in OpenSSL before version 1.1.0.</p>
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<p><code>HMAC_CTX_new()</code>, <code>HMAC_CTX_free()</code> and <code>HMAC_CTX_get_md()</code> are new in OpenSSL 1.1.0.</p>
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<p><code>HMAC_Init_ex()</code>, <code>HMAC_Update()</code> and <code>HMAC_Final()</code> did not return values in
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OpenSSL before version 1.0.0.</p>
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<p>
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</p>
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<hr />
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<h1><a name="copyright">COPYRIGHT</a></h1>
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<p>Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.</p>
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<p>Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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<a href="https://www.openssl.org/source/license.html">https://www.openssl.org/source/license.html</a>.</p>
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</body>
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</html>
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