'\" t
.\"     Title: kcapi_aead_stream_init_enc
.\"    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_AEAD_STREAM_IN" "3" "April 2024" "libkcapi Manual 1\&.4\&.0" "Programming Interface"
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.SH "NAME"
kcapi_aead_stream_init_enc \- start an encryption operation (stream)
.SH "SYNOPSIS"
.HP \w'ssize_t\ kcapi_aead_stream_init_enc('u
.BI "ssize_t kcapi_aead_stream_init_enc(struct\ kcapi_handle\ *\ " "handle" ", const\ uint8_t\ *\ " "iv" ", struct\ iovec\ *\ " "iov" ", size_t\ " "iovlen" ");"
.SH "ARGUMENTS"
.PP
\fIhandle\fR
.RS 4
[in] cipher handle
.RE
.PP
\fIiv\fR
.RS 4
[in] IV to be used for cipher operation
.RE
.PP
\fIiov\fR
.RS 4
[in] scatter/gather list with data to be encrypted\&. This is the pointer to the first iov entry if an array of iov entries is supplied\&. See sendmsg(2) for details on how iov is to be used\&. This pointer may be NULL if no data to be encrypted is available at the point of the call\&.
.RE
.PP
\fIiovlen\fR
.RS 4
[in] number of scatter/gather list elements\&. If iov is NULL, this value must be zero\&.
.RE
.SH "DESCRIPTION"
.PP
A stream encryption operation is started with this call\&. Multiple successive
\fBkcapi_aead_stream_update\fR
function calls can be invoked to send more plaintext data to be encrypted\&. The kernel buffers the input until
\fBkcapi_aead_stream_op\fR
picks up the encrypted data\&. Once plaintext is encrypted during the
\fBkcapi_aead_stream_op\fR
it is removed from the kernel buffer\&.
.PP
Note, unlike the corresponding symmetric cipher API, the function calls of
\fBkcapi_aead_stream_update\fR
and
\fBkcapi_aead_stream_op\fR
cannot be mixed! This due to the nature of AEAD where the cipher operation ensures the integrity of the entire data (decryption) or calculates a message digest over the entire data (encryption)\&.
.PP
When using the stream API, the caller must ensure that data is sent in the correct order (regardless whether data is sent in multiple chunks using
\fBkcapi_aead_stream_init_enc\fR
or
\fBkcapi_cipher_stream_update\fR): (i) the complete associated data must be provided, followed by (ii) the plaintext\&.
.PP
The IV buffer must be exactly
\fBkcapi_cipher_ivsize\fR
bytes in size\&.
.PP
\fIreturn\fR
number of bytes sent to the kernel 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