240 lines
9.0 KiB
HTML
240 lines
9.0 KiB
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<?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>EVP_KDF-SS</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="#description">DESCRIPTION</a></li>
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<ul>
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<li><a href="#auxiliary_function">Auxiliary function</a></li>
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<li><a href="#identity">Identity</a></li>
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<li><a href="#supported_parameters">Supported parameters</a></li>
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</ul>
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<li><a href="#notes">NOTES</a></li>
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<li><a href="#examples">EXAMPLES</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>EVP_KDF-SS - The Single Step / One Step EVP_KDF implementation</p>
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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>The EVP_KDF-SS algorithm implements the Single Step key derivation function (SSKDF).
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SSKDF derives a key using input such as a shared secret key (that was generated
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during the execution of a key establishment scheme) and fixedinfo.
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SSKDF is also informally referred to as 'Concat KDF'.</p>
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<p>
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</p>
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<h2><a name="auxiliary_function">Auxiliary function</a></h2>
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<p>The implementation uses a selectable auxiliary function H, which can be one of:</p>
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<dl>
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<dt><strong><a name="h" class="item"><strong>H(x) = hash(x, digest=md)</strong></a></strong></dt>
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<dt><strong><strong>H(x) = HMAC_hash(x, key=salt, digest=md)</strong></strong></dt>
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<dt><strong><strong>H(x) = KMACxxx(x, key=salt, custom="KDF", outlen=mac_size)</strong></strong></dt>
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</dl>
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<p>Both the HMAC and KMAC implementations set the key using the 'salt' value.
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The hash and HMAC also require the digest to be set.</p>
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<p>
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</p>
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<h2><a name="identity">Identity</a></h2>
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<p>"SSKDF" is the name for this implementation; it
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can be used with the <code>EVP_KDF_fetch()</code> function.</p>
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<p>
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</p>
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<h2><a name="supported_parameters">Supported parameters</a></h2>
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<p>The supported parameters are:</p>
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<dl>
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<dt><strong><a name="properties_ossl_kdf_param_properties_utf8_string" class="item">"properties" (<strong>OSSL_KDF_PARAM_PROPERTIES</strong>) <UTF8 string></a></strong></dt>
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<dt><strong><a name="digest_ossl_kdf_param_digest_utf8_string" class="item">"digest" (<strong>OSSL_KDF_PARAM_DIGEST</strong>) <UTF8 string></a></strong></dt>
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<dt><strong><a name="mac_ossl_kdf_param_mac_utf8_string" class="item">"mac" (<strong>OSSL_KDF_PARAM_MAC</strong>) <UTF8 string></a></strong></dt>
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<dt><strong><a name="maclen_ossl_kdf_param_mac_size_unsigned_integer" class="item">"maclen" (<strong>OSSL_KDF_PARAM_MAC_SIZE</strong>) <unsigned integer></a></strong></dt>
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<dt><strong><a name="salt_ossl_kdf_param_salt_octet_string" class="item">"salt" (<strong>OSSL_KDF_PARAM_SALT</strong>) <octet string></a></strong></dt>
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<dd>
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<p>These parameters work as described in <em>EVP_KDF(3)/PARAMETERS</em>.</p>
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</dd>
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<dt><strong><a name="key_evp_kdf_ctrl_set_key_octet_string" class="item">"key" (<strong>EVP_KDF_CTRL_SET_KEY</strong>) <octet string></a></strong></dt>
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<dd>
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<p>This parameter set the shared secret that is used for key derivation.</p>
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</dd>
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<dt><strong><a name="info_ossl_kdf_param_info_octet_string" class="item">"info" (<strong>OSSL_KDF_PARAM_INFO</strong>) <octet string></a></strong></dt>
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<dd>
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<p>This parameter sets an optional value for fixedinfo, also known as otherinfo.</p>
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</dd>
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</dl>
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<p>
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</p>
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<hr />
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<h1><a name="notes">NOTES</a></h1>
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<p>A context for SSKDF can be obtained by calling:</p>
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<pre>
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EVP_KDF *kdf = EVP_KDF_fetch(NULL, "SSKDF", NULL);
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EVP_KDF_CTX *kctx = EVP_KDF_CTX_new(kdf);</pre>
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<p>The output length of an SSKDF is specified via the <em>keylen</em>
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parameter to the <em>EVP_KDF_derive(3)</em> function.</p>
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<p>
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</p>
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<hr />
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<h1><a name="examples">EXAMPLES</a></h1>
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<p>This example derives 10 bytes using H(x) = SHA-256, with the secret key "secret"
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and fixedinfo value "label":</p>
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<pre>
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EVP_KDF *kdf;
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EVP_KDF_CTX *kctx;
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unsigned char out[10];
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OSSL_PARAM params[4], *p = params;</pre>
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<pre>
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kdf = EVP_KDF_fetch(NULL, "SSKDF", NULL);
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kctx = EVP_KDF_CTX_new(kdf);
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EVP_KDF_free(kdf);</pre>
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<pre>
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*p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_DIGEST,
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SN_sha256, strlen(SN_sha256));
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*p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_KEY,
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"secret", (size_t)6);
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*p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_INFO,
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"label", (size_t)5);
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*p = OSSL_PARAM_construct_end();
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if (EVP_KDF_CTX_set_params(kctx, params) <= 0) {
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error("EVP_KDF_CTX_set_params");
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}
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if (EVP_KDF_derive(kctx, out, sizeof(out)) <= 0) {
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error("EVP_KDF_derive");
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}</pre>
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<pre>
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EVP_KDF_CTX_free(kctx);</pre>
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<p>This example derives 10 bytes using H(x) = HMAC(SHA-256), with the secret key "secret",
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fixedinfo value "label" and salt "salt":</p>
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<pre>
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EVP_KDF *kdf;
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EVP_KDF_CTX *kctx;
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unsigned char out[10];
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OSSL_PARAM params[6], *p = params;</pre>
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<pre>
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kdf = EVP_KDF_fetch(NULL, "SSKDF", NULL);
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kctx = EVP_KDF_CTX_new(kdf);
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EVP_KDF_free(kdf);</pre>
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<pre>
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*p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_MAC,
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SN_hmac, strlen(SN_hmac));
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*p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_DIGEST,
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SN_sha256, strlen(SN_sha256));
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*p++ = OSSL_PARAM_construct_octet_string(EVP_KDF_CTRL_SET_KEY,
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"secret", (size_t)6);
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*p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_INFO,
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"label", (size_t)5);
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*p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_SALT,
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"salt", (size_t)4);
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*p = OSSL_PARAM_construct_end();
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if (EVP_KDF_CTX_set_params(kctx, params) <= 0) {
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error("EVP_KDF_CTX_set_params");
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}
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if (EVP_KDF_derive(kctx, out, sizeof(out)) <= 0) {
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error("EVP_KDF_derive");
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}</pre>
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<pre>
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EVP_KDF_CTX_free(kctx);</pre>
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<p>This example derives 10 bytes using H(x) = KMAC128(x,salt,outlen), with the secret key "secret"
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fixedinfo value "label", salt of "salt" and KMAC outlen of 20:</p>
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<pre>
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EVP_KDF *kdf;
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EVP_KDF_CTX *kctx;
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unsigned char out[10];
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OSSL_PARAM params[7], *p = params;</pre>
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<pre>
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kdf = EVP_KDF_fetch(NULL, "SSKDF", NULL);
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kctx = EVP_KDF_CTX_new(kdf);
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EVP_KDF_free(kdf);</pre>
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<pre>
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*p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_MAC,
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SN_kmac128, strlen(SN_kmac128));
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*p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_DIGEST,
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SN_sha256, strlen(SN_sha256));
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*p++ = OSSL_PARAM_construct_octet_string(EVP_KDF_CTRL_SET_KEY,
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"secret", (size_t)6);
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*p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_INFO,
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"label", (size_t)5);
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*p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_SALT,
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"salt", (size_t)4);
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*p++ = OSSL_PARAM_construct_size_t(OSSL_KDF_PARAM_MAC_SIZE, (size_t)20);
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*p = OSSL_PARAM_construct_end();
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if (EVP_KDF_CTX_set_params(kctx, params) <= 0) {
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error("EVP_KDF_CTX_set_params");
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}
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if (EVP_KDF_derive(kctx, out, sizeof(out)) <= 0) {
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error("EVP_KDF_derive");
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}</pre>
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<pre>
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EVP_KDF_CTX_free(kctx);</pre>
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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>NIST SP800-56Cr1.</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>EVP_KDF(3)</em>,
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<em>EVP_KDF_CTX_new(3)</em>,
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<em>EVP_KDF_CTX_free(3)</em>,
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<em>EVP_KDF_CTX_set_params(3)</em>,
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<em>EVP_KDF_size(3)</em>,
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<em>EVP_KDF_derive(3)</em>,
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<em>EVP_KDF(3)/PARAMETERS</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>This functionality was added to OpenSSL 3.0.</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 2019 The OpenSSL Project Authors. All Rights Reserved. Copyright
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(c) 2019, Oracle and/or its affiliates. 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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