.\" $NetBSD: EVP_KDF-X942-ASN1.7,v 1.2.2.3 2023/11/02 19:32:23 sborrill Exp $ .\" .\" Automatically generated by Pod::Man 4.14 (Pod::Simple 3.43) .\" .\" Standard preamble: .\" ======================================================================== .de Sp \" Vertical space (when we can't use .PP) .if t .sp .5v .if n .sp .. .de Vb \" Begin verbatim text .ft CW .nf .ne \\$1 .. .de Ve \" End verbatim text .ft R .fi .. .\" Set up some character translations and predefined strings. \*(-- will .\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left .\" double quote, and \*(R" will give a right double quote. \*(C+ will .\" give a nicer C++. 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Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" EVP_KDF\-X942\-ASN1 \- The X9.42\-2003 asn1 EVP_KDF implementation .SH "DESCRIPTION" .IX Header "DESCRIPTION" The \s-1EVP_KDF\-X942\-ASN1\s0 algorithm implements the key derivation function X942KDF\-ASN1. It is used by \s-1DH\s0 KeyAgreement, to derive a key using input such as a shared secret key and other info. The other info is \s-1DER\s0 encoded data that contains a 32 bit counter as well as optional fields for \*(L"partyu-info\*(R", \&\*(L"partyv-info\*(R", \*(L"supp-pubinfo\*(R" and \*(L"supp-privinfo\*(R". This kdf is used by Cryptographic Message Syntax (\s-1CMS\s0). .SS "Identity" .IX Subsection "Identity" \&\*(L"X942KDF\-ASN1\*(R" or \*(L"X942KDF\*(R" is the name for this implementation; it can be used with the \fBEVP_KDF_fetch()\fR function. .SS "Supported parameters" .IX Subsection "Supported parameters" The supported parameters are: .ie n .IP """properties"" (\fB\s-1OSSL_KDF_PARAM_PROPERTIES\s0\fR) <\s-1UTF8\s0 string>" 4 .el .IP "``properties'' (\fB\s-1OSSL_KDF_PARAM_PROPERTIES\s0\fR) <\s-1UTF8\s0 string>" 4 .IX Item "properties (OSSL_KDF_PARAM_PROPERTIES) " .PD 0 .ie n .IP """digest"" (\fB\s-1OSSL_KDF_PARAM_DIGEST\s0\fR) <\s-1UTF8\s0 string>" 4 .el .IP "``digest'' (\fB\s-1OSSL_KDF_PARAM_DIGEST\s0\fR) <\s-1UTF8\s0 string>" 4 .IX Item "digest (OSSL_KDF_PARAM_DIGEST) " .PD These parameters work as described in \*(L"\s-1PARAMETERS\*(R"\s0 in \s-1\fBEVP_KDF\s0\fR\|(3). .ie n .IP """secret"" (\fB\s-1OSSL_KDF_PARAM_SECRET\s0\fR) " 4 .el .IP "``secret'' (\fB\s-1OSSL_KDF_PARAM_SECRET\s0\fR) " 4 .IX Item "secret (OSSL_KDF_PARAM_SECRET) " The shared secret used for key derivation. This parameter sets the secret. .ie n .IP """acvp-info"" (\fB\s-1OSSL_KDF_PARAM_X942_ACVPINFO\s0\fR) " 4 .el .IP "``acvp-info'' (\fB\s-1OSSL_KDF_PARAM_X942_ACVPINFO\s0\fR) " 4 .IX Item "acvp-info (OSSL_KDF_PARAM_X942_ACVPINFO) " This value should not be used in production and should only be used for \s-1ACVP\s0 testing. It is an optional octet string containing a combined \s-1DER\s0 encoded blob of any of the optional fields related to \*(L"partyu-info\*(R", \*(L"partyv-info\*(R", \&\*(L"supp-pubinfo\*(R" and \*(L"supp-privinfo\*(R". If it is specified then none of these other fields should be used. .ie n .IP """partyu-info"" (\fB\s-1OSSL_KDF_PARAM_X942_PARTYUINFO\s0\fR) " 4 .el .IP "``partyu-info'' (\fB\s-1OSSL_KDF_PARAM_X942_PARTYUINFO\s0\fR) " 4 .IX Item "partyu-info (OSSL_KDF_PARAM_X942_PARTYUINFO) " An optional octet string containing public info contributed by the initiator. .ie n .IP """ukm"" (\fB\s-1OSSL_KDF_PARAM_UKM\s0\fR) " 4 .el .IP "``ukm'' (\fB\s-1OSSL_KDF_PARAM_UKM\s0\fR) " 4 .IX Item "ukm (OSSL_KDF_PARAM_UKM) " An alias for \*(L"partyu-info\*(R". In \s-1CMS\s0 this is the user keying material. .ie n .IP """partyv-info"" (\fB\s-1OSSL_KDF_PARAM_X942_PARTYVINFO\s0\fR) " 4 .el .IP "``partyv-info'' (\fB\s-1OSSL_KDF_PARAM_X942_PARTYVINFO\s0\fR) " 4 .IX Item "partyv-info (OSSL_KDF_PARAM_X942_PARTYVINFO) " An optional octet string containing public info contributed by the responder. .ie n .IP """supp-pubinfo"" (\fB\s-1OSSL_KDF_PARAM_X942_SUPP_PUBINFO\s0\fR) " 4 .el .IP "``supp-pubinfo'' (\fB\s-1OSSL_KDF_PARAM_X942_SUPP_PUBINFO\s0\fR) " 4 .IX Item "supp-pubinfo (OSSL_KDF_PARAM_X942_SUPP_PUBINFO) " An optional octet string containing some additional, mutually-known public information. Setting this value also sets \*(L"use-keybits\*(R" to 0. .ie n .IP """use-keybits"" (\fB\s-1OSSL_KDF_PARAM_X942_USE_KEYBITS\s0\fR) " 4 .el .IP "``use-keybits'' (\fB\s-1OSSL_KDF_PARAM_X942_USE_KEYBITS\s0\fR) " 4 .IX Item "use-keybits (OSSL_KDF_PARAM_X942_USE_KEYBITS) " The default value of 1 will use the \s-1KEK\s0 key length (in bits) as the \&\*(L"supp-pubinfo\*(R". A value of 0 disables setting the \*(L"supp-pubinfo\*(R". .ie n .IP """supp-privinfo"" (\fB\s-1OSSL_KDF_PARAM_X942_SUPP_PRIVINFO\s0\fR) " 4 .el .IP "``supp-privinfo'' (\fB\s-1OSSL_KDF_PARAM_X942_SUPP_PRIVINFO\s0\fR) " 4 .IX Item "supp-privinfo (OSSL_KDF_PARAM_X942_SUPP_PRIVINFO) " An optional octet string containing some additional, mutually-known private information. .ie n .IP """cekalg"" (\fB\s-1OSSL_KDF_PARAM_CEK_ALG\s0\fR) <\s-1UTF8\s0 string>" 4 .el .IP "``cekalg'' (\fB\s-1OSSL_KDF_PARAM_CEK_ALG\s0\fR) <\s-1UTF8\s0 string>" 4 .IX Item "cekalg (OSSL_KDF_PARAM_CEK_ALG) " This parameter sets the \s-1CEK\s0 wrapping algorithm name. Valid values are \*(L"\s-1AES\-128\-WRAP\*(R", \*(L"AES\-192\-WRAP\*(R", \*(L"AES\-256\-WRAP\*(R"\s0 and \*(L"\s-1DES3\-WRAP\*(R".\s0 .SH "NOTES" .IX Header "NOTES" A context for X942KDF can be obtained by calling: .PP .Vb 2 \& EVP_KDF *kdf = EVP_KDF_fetch(NULL, "X942KDF", NULL); \& EVP_KDF_CTX *kctx = EVP_KDF_CTX_new(kdf); .Ve .PP The output length of an X942KDF is specified via the \fIkeylen\fR parameter to the \fBEVP_KDF_derive\fR\|(3) function. .SH "EXAMPLES" .IX Header "EXAMPLES" This example derives 24 bytes, with the secret key \*(L"secret\*(R" and random user keying material: .PP .Vb 5 \& 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); .Ve .SH "CONFORMING TO" .IX Header "CONFORMING TO" \&\s-1ANS1 X9.42\-2003 RFC 2631\s0 .SH "SEE ALSO" .IX Header "SEE ALSO" \&\s-1\fBEVP_KDF\s0\fR\|(3), \&\fBEVP_KDF_CTX_new\fR\|(3), \&\fBEVP_KDF_CTX_free\fR\|(3), \&\fBEVP_KDF_CTX_set_params\fR\|(3), \&\fBEVP_KDF_CTX_get_kdf_size\fR\|(3), \&\fBEVP_KDF_derive\fR\|(3), \&\*(L"\s-1PARAMETERS\*(R"\s0 in \s-1\fBEVP_KDF\s0\fR\|(3) .SH "HISTORY" .IX Header "HISTORY" This functionality was added in OpenSSL 3.0. .SH "COPYRIGHT" .IX Header "COPYRIGHT" Copyright 2019\-2022 The OpenSSL Project Authors. All Rights Reserved. .PP Licensed under the Apache License 2.0 (the \*(L"License\*(R"). You may not use this file except in compliance with the License. You can obtain a copy in the file \s-1LICENSE\s0 in the source distribution or at .