.\" $NetBSD: EVP_KDF-X963.7,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\-X963 \- The X9.63\-2001 EVP_KDF implementation .SH "DESCRIPTION" .IX Header "DESCRIPTION" The \s-1EVP_KDF\-X963\s0 algorithm implements the key derivation function (X963KDF). X963KDF is used by Cryptographic Message Syntax (\s-1CMS\s0) for \s-1EC\s0 KeyAgreement, to derive a key using input such as a shared secret key and shared info. .SS "Identity" .IX Subsection "Identity" \&\*(L"X963KDF\*(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 """key"" (\fB\s-1OSSL_KDF_PARAM_KEY\s0\fR) " 4 .el .IP "``key'' (\fB\s-1OSSL_KDF_PARAM_KEY\s0\fR) " 4 .IX Item "key (OSSL_KDF_PARAM_KEY) " The shared secret used for key derivation. This parameter sets the secret. .ie n .IP """info"" (\fB\s-1OSSL_KDF_PARAM_INFO\s0\fR) " 4 .el .IP "``info'' (\fB\s-1OSSL_KDF_PARAM_INFO\s0\fR) " 4 .IX Item "info (OSSL_KDF_PARAM_INFO) " This parameter specifies an optional value for shared info. .SH "NOTES" .IX Header "NOTES" X963KDF is very similar to the \s-1SSKDF\s0 that uses a digest as the auxiliary function, X963KDF appends the counter to the secret, whereas \s-1SSKDF\s0 prepends the counter. .PP A context for X963KDF can be obtained by calling: .PP .Vb 2 \& EVP_KDF *kdf = EVP_KDF_fetch(NULL, "X963KDF", NULL); \& EVP_KDF_CTX *kctx = EVP_KDF_CTX_new(kdf); .Ve .PP The output length of an X963KDF is specified via the \fIkeylen\fR parameter to the \fBEVP_KDF_derive\fR\|(3) function. .SH "EXAMPLES" .IX Header "EXAMPLES" This example derives 10 bytes, with the secret key \*(L"secret\*(R" and sharedinfo value \*(L"label\*(R": .PP .Vb 4 \& EVP_KDF *kdf; \& EVP_KDF_CTX *kctx; \& unsigned char out[10]; \& OSSL_PARAM params[4], *p = params; \& \& kdf = EVP_KDF_fetch(NULL, "X963KDF", NULL); \& kctx = EVP_KDF_CTX_new(kdf); \& EVP_KDF_free(kdf); \& \& *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_DIGEST, \& SN_sha256, strlen(SN_sha256)); \& *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_SECRET, \& "secret", (size_t)6); \& *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_INFO, \& "label", (size_t)5); \& *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" \&\*(L"\s-1SEC 1:\s0 Elliptic Curve Cryptography\*(R" .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\-2021 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 .