'\" t
.\"     Title: aead_request_set_crypt
.\"    Author: 
.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
.\"      Date: January 2017
.\"    Manual: Programming Interface
.\"    Source: Kernel Hackers Manual 4.8.15
.\"  Language: English
.\"
.TH "AEAD_REQUEST_SET_CRY" "9" "January 2017" "Kernel Hackers Manual 4\&.8\&." "Programming Interface"
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.SH "NAME"
aead_request_set_crypt \- set data buffers
.SH "SYNOPSIS"
.HP \w'void\ aead_request_set_crypt('u
.BI "void aead_request_set_crypt(struct\ aead_request\ *\ " "req" ", struct\ scatterlist\ *\ " "src" ", struct\ scatterlist\ *\ " "dst" ", unsigned\ int\ " "cryptlen" ", u8\ *\ " "iv" ");"
.SH "ARGUMENTS"
.PP
\fIreq\fR
.RS 4
request handle
.RE
.PP
\fIsrc\fR
.RS 4
source scatter / gather list
.RE
.PP
\fIdst\fR
.RS 4
destination scatter / gather list
.RE
.PP
\fIcryptlen\fR
.RS 4
number of bytes to process from
\fIsrc\fR
.RE
.PP
\fIiv\fR
.RS 4
IV for the cipher operation which must comply with the IV size defined by
\fBcrypto_aead_ivsize\fR
.RE
.SH "DESCRIPTION"
.PP
Setting the source data and destination data scatter / gather lists which hold the associated data concatenated with the plaintext or ciphertext\&. See below for the authentication tag\&.
.PP
For encryption, the source is treated as the plaintext and the destination is the ciphertext\&. For a decryption operation, the use is reversed \- the source is the ciphertext and the destination is the plaintext\&.
.PP
For both src/dst the layout is associated data, plain/cipher text, authentication tag\&.
.PP
The content of the AD in the destination buffer after processing will either be untouched, or it will contain a copy of the AD from the source buffer\&. In order to ensure that it always has a copy of the AD, the user must copy the AD over either before or after processing\&. Of course this is not relevant if the user is doing in\-place processing where src == dst\&.
.PP
IMPORTANT NOTE AEAD requires an authentication tag (MAC)\&. For decryption, the caller must concatenate the ciphertext followed by the authentication tag and provide the entire data stream to the decryption operation (i\&.e\&. the data length used for the initialization of the scatterlist and the data length for the decryption operation is identical)\&. For encryption, however, the authentication tag is created while encrypting the data\&. The destination buffer must hold sufficient space for the ciphertext and the authentication tag while the encryption invocation must only point to the plaintext data size\&. The following code snippet illustrates the memory usage buffer = kmalloc(ptbuflen + (enc ? authsize : 0)); sg_init_one(sg, buffer, ptbuflen + (enc ? authsize : 0)); aead_request_set_crypt(req,
sg,
sg, ptbuflen, iv);
.SH "AUTHORS"
.PP
\fBStephan Mueller\fR <\&smueller@chronox.de\&>
.RS 4
Author.
.RE
.PP
\fBMarek Vasut\fR <\&marek@denx.de\&>
.RS 4
Author.
.RE
.SH "COPYRIGHT"
.br