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<?xml version="1.0" ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>EVP_KDF-X942-ASN1</title> <meta http-equiv="content-type" content="text/html; charset=utf-8" /> <link rev="made" href="mailto:root@localhost" /> </head> <body style="background-color: white"> <ul id="index"> <li><a href="#NAME">NAME</a></li> <li><a href="#DESCRIPTION">DESCRIPTION</a> <ul> <li><a href="#Identity">Identity</a></li> <li><a href="#Supported-parameters">Supported parameters</a></li> </ul> </li> <li><a href="#NOTES">NOTES</a></li> <li><a href="#EXAMPLES">EXAMPLES</a></li> <li><a href="#CONFORMING-TO">CONFORMING TO</a></li> <li><a href="#SEE-ALSO">SEE ALSO</a></li> <li><a href="#HISTORY">HISTORY</a></li> <li><a href="#COPYRIGHT">COPYRIGHT</a></li> </ul> <h1 id="NAME">NAME</h1> <p>EVP_KDF-X942-ASN1 - The X9.42-2003 asn1 EVP_KDF implementation</p> <h1 id="DESCRIPTION">DESCRIPTION</h1> <p>The EVP_KDF-X942-ASN1 algorithm implements the key derivation function X942KDF-ASN1. It is used by DH KeyAgreement, to derive a key using input such as a shared secret key and other info. The other info is DER encoded data that contains a 32 bit counter as well as optional fields for "partyu-info", "partyv-info", "supp-pubinfo" and "supp-privinfo". This kdf is used by Cryptographic Message Syntax (CMS).</p> <h2 id="Identity">Identity</h2> <p>"X942KDF-ASN1" or "X942KDF" is the name for this implementation; it can be used with the EVP_KDF_fetch() function.</p> <h2 id="Supported-parameters">Supported parameters</h2> <p>The supported parameters are:</p> <dl> <dt id="properties-OSSL_KDF_PARAM_PROPERTIES-UTF8-string">"properties" (<b>OSSL_KDF_PARAM_PROPERTIES</b>) <UTF8 string></dt> <dd> </dd> <dt id="digest-OSSL_KDF_PARAM_DIGEST-UTF8-string">"digest" (<b>OSSL_KDF_PARAM_DIGEST</b>) <UTF8 string></dt> <dd> <p>These parameters work as described in <a href="../man3/EVP_KDF.html">"PARAMETERS" in EVP_KDF(3)</a>.</p> </dd> <dt id="secret-OSSL_KDF_PARAM_SECRET-octet-string">"secret" (<b>OSSL_KDF_PARAM_SECRET</b>) <octet string></dt> <dd> <p>The shared secret used for key derivation. This parameter sets the secret.</p> </dd> <dt id="acvp-info-OSSL_KDF_PARAM_X942_ACVPINFO-octet-string">"acvp-info" (<b>OSSL_KDF_PARAM_X942_ACVPINFO</b>) <octet string></dt> <dd> <p>This value should not be used in production and should only be used for ACVP testing. It is an optional octet string containing a combined DER encoded blob of any of the optional fields related to "partyu-info", "partyv-info", "supp-pubinfo" and "supp-privinfo". If it is specified then none of these other fields should be used.</p> </dd> <dt id="partyu-info-OSSL_KDF_PARAM_X942_PARTYUINFO-octet-string">"partyu-info" (<b>OSSL_KDF_PARAM_X942_PARTYUINFO</b>) <octet string></dt> <dd> <p>An optional octet string containing public info contributed by the initiator.</p> </dd> <dt id="ukm-OSSL_KDF_PARAM_UKM-octet-string">"ukm" (<b>OSSL_KDF_PARAM_UKM</b>) <octet string></dt> <dd> <p>An alias for "partyu-info". In CMS this is the user keying material.</p> </dd> <dt id="partyv-info-OSSL_KDF_PARAM_X942_PARTYVINFO-octet-string">"partyv-info" (<b>OSSL_KDF_PARAM_X942_PARTYVINFO</b>) <octet string></dt> <dd> <p>An optional octet string containing public info contributed by the responder.</p> </dd> <dt id="supp-pubinfo-OSSL_KDF_PARAM_X942_SUPP_PUBINFO-octet-string">"supp-pubinfo" (<b>OSSL_KDF_PARAM_X942_SUPP_PUBINFO</b>) <octet string></dt> <dd> <p>An optional octet string containing some additional, mutually-known public information. Setting this value also sets "use-keybits" to 0.</p> </dd> <dt id="use-keybits-OSSL_KDF_PARAM_X942_USE_KEYBITS-integer">"use-keybits" (<b>OSSL_KDF_PARAM_X942_USE_KEYBITS</b>) <integer></dt> <dd> <p>The default value of 1 will use the KEK key length (in bits) as the "supp-pubinfo". A value of 0 disables setting the "supp-pubinfo".</p> </dd> <dt id="supp-privinfo-OSSL_KDF_PARAM_X942_SUPP_PRIVINFO-octet-string">"supp-privinfo" (<b>OSSL_KDF_PARAM_X942_SUPP_PRIVINFO</b>) <octet string></dt> <dd> <p>An optional octet string containing some additional, mutually-known private information.</p> </dd> <dt id="cekalg-OSSL_KDF_PARAM_CEK_ALG-UTF8-string">"cekalg" (<b>OSSL_KDF_PARAM_CEK_ALG</b>) <UTF8 string></dt> <dd> <p>This parameter sets the CEK wrapping algorithm name. Valid values are "AES-128-WRAP", "AES-192-WRAP", "AES-256-WRAP" and "DES3-WRAP".</p> </dd> </dl> <h1 id="NOTES">NOTES</h1> <p>A context for X942KDF can be obtained by calling:</p> <pre><code> EVP_KDF *kdf = EVP_KDF_fetch(NULL, "X942KDF", NULL); EVP_KDF_CTX *kctx = EVP_KDF_CTX_new(kdf);</code></pre> <p>The output length of an X942KDF is specified via the <i>keylen</i> parameter to the <a href="../man3/EVP_KDF_derive.html">EVP_KDF_derive(3)</a> function.</p> <h1 id="EXAMPLES">EXAMPLES</h1> <p>This example derives 24 bytes, with the secret key "secret" and random user keying material:</p> <pre><code> EVP_KDF_CTX *kctx; EVP_KDF_CTX *kctx; unsigned char out[192/8]; unsignred char ukm[64]; OSSL_PARAM params[5], *p = params; if (RAND_bytes(ukm, sizeof(ukm)) <= 0) error("RAND_bytes"); kdf = EVP_KDF_fetch(NULL, "X942KDF", NULL); if (kctx == NULL) error("EVP_KDF_fetch"); kctx = EVP_KDF_CTX_new(kdf); EVP_KDF_free(kdf); if (kctx == NULL) error("EVP_KDF_CTX_new"); *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_DIGEST, "SHA256", 0); *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_SECRET, "secret", (size_t)6); *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_UKM, ukm, sizeof(ukm)); *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_CEK_ALG, "AES-256-WRAP, 0); *p = OSSL_PARAM_construct_end(); if (EVP_KDF_derive(kctx, out, sizeof(out), params) <= 0) error("EVP_KDF_derive"); EVP_KDF_CTX_free(kctx);</code></pre> <h1 id="CONFORMING-TO">CONFORMING TO</h1> <p>ANS1 X9.42-2003 RFC 2631</p> <h1 id="SEE-ALSO">SEE ALSO</h1> <p><a href="../man3/EVP_KDF.html">EVP_KDF(3)</a>, <a href="../man3/EVP_KDF_CTX_new.html">EVP_KDF_CTX_new(3)</a>, <a href="../man3/EVP_KDF_CTX_free.html">EVP_KDF_CTX_free(3)</a>, <a href="../man3/EVP_KDF_CTX_set_params.html">EVP_KDF_CTX_set_params(3)</a>, <a href="../man3/EVP_KDF_CTX_get_kdf_size.html">EVP_KDF_CTX_get_kdf_size(3)</a>, <a href="../man3/EVP_KDF_derive.html">EVP_KDF_derive(3)</a>, <a href="../man3/EVP_KDF.html">"PARAMETERS" in EVP_KDF(3)</a></p> <h1 id="HISTORY">HISTORY</h1> <p>This functionality was added to OpenSSL 3.0.</p> <h1 id="COPYRIGHT">COPYRIGHT</h1> <p>Copyright 2019-2022 The OpenSSL Project Authors. All Rights Reserved.</p> <p>Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <a href="https://www.openssl.org/source/license.html">https://www.openssl.org/source/license.html</a>.</p> </body> </html>