'\" t
.\"     Title: kcapi_hkdf
.\"    Author: 
.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
.\"      Date: April 2024
.\"    Manual: Programming Interface
.\"    Source: libkcapi Manual 1.4.0
.\"  Language: English
.\"
.TH "KCAPI_HKDF" "3" "April 2024" "libkcapi Manual 1\&.4\&.0" "Programming Interface"
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.SH "NAME"
kcapi_hkdf \- Extract\-and\-Expand HKDF (RFC5869)
.SH "SYNOPSIS"
.HP \w'ssize_t\ kcapi_hkdf('u
.BI "ssize_t kcapi_hkdf(const\ char\ *\ " "hashname" ", const\ uint8_t\ *\ " "ikm" ", size_t\ " "ikmlen" ", const\ uint8_t\ *\ " "salt" ", uint32_t\ " "saltlen" ", const\ uint8_t\ *\ " "info" ", size_t\ " "infolen" ", uint8_t\ *\ " "dst" ", size_t\ " "dlen" ");"
.SH "ARGUMENTS"
.PP
\fIhashname\fR
.RS 4
[in] kernel crypto API name of a keyed hash (e\&.g\&. hmac(sha1))
.RE
.PP
\fIikm\fR
.RS 4
[in] Input Keying Material (IKM) \-\- must be provided
.RE
.PP
\fIikmlen\fR
.RS 4
[in] IKM buffer length \-\- must be non\-zero
.RE
.PP
\fIsalt\fR
.RS 4
[in] salt buffer \-\- may be NULL
.RE
.PP
\fIsaltlen\fR
.RS 4
[in] salt buffer length \-\- may be zero
.RE
.PP
\fIinfo\fR
.RS 4
[in] info buffer \-\- may be NULL
.RE
.PP
\fIinfolen\fR
.RS 4
[in] info buffer length \-\- may be zero
.RE
.PP
\fIdst\fR
.RS 4
[out] Buffer to store the generated key in,
.RE
.PP
\fIdlen\fR
.RS 4
[in] Length of the dst buffer\&. This value defines the number of bytes generated by the KDF\&.
.RE
.SH "DESCRIPTION"
.PP
Perform the key\-derivation function according to RFC5869\&. The input data is defined in sections 2\&.2 und 2\&.3 of RFC5869\&.
.PP
\fIreturn\fR
0 upon success; a negative errno\-style error code if an error occurred
.SH "AUTHOR"
.PP
\fBStephan Mueller\fR <\&smueller@chronox.de\&>
.RS 4
Author.
.RE
.SH "COPYRIGHT"
.br