.\" DO NOT MODIFY THIS FILE!  It was generated by gdoc.
.TH "shishi_decrypt_ivupdate_etype" 3 "1.0.2" "shishi" "shishi"
.SH NAME
shishi_decrypt_ivupdate_etype \- API function
.SH SYNOPSIS
.B #include <shishi.h>
.sp
.BI "int shishi_decrypt_ivupdate_etype(Shishi * " handle ", Shishi_key * " key ", int " keyusage ", int32_t " etype ", const char * " iv ", size_t " ivlen ", char ** " ivout ", size_t * " ivoutlen ", const char * " in ", size_t " inlen ", char ** " out ", size_t * " outlen ");"
.SH ARGUMENTS
.IP "Shishi * handle" 12
shishi handle as allocated by \fBshishi_init()\fP.
.IP "Shishi_key * key" 12
key to decrypt with.
.IP "int keyusage" 12
integer specifying what this key is decrypting.
.IP "int32_t etype" 12
integer specifying what cipher to use.
.IP "const char * iv" 12
input array with initialization vector
.IP "size_t ivlen" 12
size of input array with initialization vector.
.IP "char ** ivout" 12
output array with newly allocated updated initialization vector.
.IP "size_t * ivoutlen" 12
size of output array with updated initialization vector.
.IP "const char * in" 12
input array with data to decrypt.
.IP "size_t inlen" 12
size of input array with data to decrypt.
.IP "char ** out" 12
output array with newly allocated decrypted data.
.IP "size_t * outlen" 12
output variable with size of newly allocated output array.
.SH "DESCRIPTION"
Decrypts data as per encryption method using specified
initialization vector and key.  The key actually used is derived
using the key usage.  If key usage is 0, no key derivation is used.
The OUT buffer must be deallocated by the caller.  If IVOUT or
IVOUTLEN is NULL, the updated IV is not saved anywhere.

Note that DECRYPT(ENCRYPT(data)) does not necessarily yield data
exactly.  Some encryption types add pad to make the data fit into
the block size of the encryption algorithm.  Furthermore, the pad
is not guaranteed to look in any special way, although existing
implementations often pad with the zero byte.  This means that you
may have to "frame" data, so it is possible to infer the original
length after decryption.  Compare ASN.1 DER which contains such
information.
.SH "RETURN VALUE"
Returns \fBSHISHI_OK\fP iff successful.
.SH "REPORTING BUGS"
Report bugs to <bug-shishi@gnu.org>.
.SH COPYRIGHT
Copyright \(co 2002-2010 Simon Josefsson.
.br
Copying and distribution of this file, with or without modification,
are permitted in any medium without royalty provided the copyright
notice and this notice are preserved.
.SH "SEE ALSO"
The full documentation for
.B shishi
is maintained as a Texinfo manual.  If the
.B info
and
.B shishi
programs are properly installed at your site, the command
.IP
.B info shishi
.PP
should give you access to the complete manual.