'\" t
.\"     Title: kcapi_kpp_setkey
.\"    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_KPP_SETKEY" "3" "April 2024" "libkcapi Manual 1\&.4\&.0" "Programming Interface"
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.SH "NAME"
kcapi_kpp_setkey \- set the private key of the DH / ECDH operation
.SH "SYNOPSIS"
.HP \w'int\ kcapi_kpp_setkey('u
.BI "int kcapi_kpp_setkey(struct\ kcapi_handle\ *\ " "handle" ", const\ uint8_t\ *\ " "key" ", uint32_t\ " "keylen" ");"
.SH "ARGUMENTS"
.PP
\fIhandle\fR
.RS 4
[in] cipher handle
.RE
.PP
\fIkey\fR
.RS 4
[in] key buffer
.RE
.PP
\fIkeylen\fR
.RS 4
[in] length of key buffer
.RE
.SH "DESCRIPTION"
.PP
With this function, the caller sets the key for subsequent DH / ECDH public key generation or shared secret generation operations\&.
.PP
If the key / keylen is zero, the kernel tries to generate the private key itself and retains it internally\&. This is useful if the DH / ECDH operation shall be performed on ephemeral keys where the caller is only interested in eventually obtain the shared secret\&.
.PP
After the caller provided the key, the caller may securely destroy the key as it is now maintained by the kernel\&.
.PP
Note, the key can only be set after the DH parameters or the ECC curve has been set\&.
.PP
\fIreturn\fR
in case of success a positive integer is returned that denominates the maximum output size of the cryptographic operation \-\- this value must be used as the size of the output buffer for one cryptographic operation); a negative errno\-style error code if an error occurred \-\- the error \-EOPNOTSUPP is returned in case a kernel\-triggered private key generation is requested, but the underlying cipher implementation does not support this operation\&.
.SH "AUTHOR"
.PP
\fBStephan Mueller\fR <\&smueller@chronox.de\&>
.RS 4
Author.
.RE
.SH "COPYRIGHT"
.br