.TH LIBKECCAK_DEGENERALISE_SPEC 3 LIBKECCAK-%VERSION%
.SH NAME
libkeccak_degeneralise_spec - Set all specification parameters to automatic
.SH SYNOPSIS
.LP
.nf
#include <libkeccak.h>
.P
int libkeccak_degeneralise_spec(libkeccak_generalised_spec_t *\fIspec\fP,
                                libkeccak_spec_t *\fIoutput_spec\fP);
.fi
.P
Link with \fI-lkeccak\fP.
.SH DESCRIPTION
The
.BR libkeccak_degeneralise_spec ()
function will resolve automatic parameters in \fI*spec\fP
and translates the parameters to \fI*output_spec\fP,
so that it can be used for hashing.
.PP
The function will modify both \fI*spec\fP and \fI*output_spec\fP.
.PP
You should call the
.BR libkeccak_spec_check (3)
function after calling
.BR libkeccak_degeneralise_spec ().
.PP
.nf
typedef struct libkeccak_generalised_spec {
    long bitrate;     /* bitrate (in bits) */
    long capacity;    /* capacity (in bits) */
    long output;      /* output size (in bits) */
    long state_size;  /* state size (in bits) */
    long word_size;   /* word size (in bits) */
} libkeccak_generalised_spec_t;
.fi
.SH RETURN VALUES
The
.BR libkeccak_degeneralise_spec ()
function returns 0 if the settings are usable. Otherwise
it will return one of the following constants.
.PP
.TP
.B LIBKECCAK_GENERALISED_SPEC_ERROR_STATE_NONPOSITIVE
The specified state size is non-positive.
.TP
.B LIBKECCAK_GENERALISED_SPEC_ERROR_STATE_TOO_LARGE
The specified state size exceeded the supported limit
(currently at 1600 bits.)
.TP
.B LIBKECCAK_GENERALISED_SPEC_ERROR_STATE_MOD_25
The specified state size, in bits, was not equivalent
to 0 modulus 25. Meaning the state size cannot
cover all lanes equivalently.
.TP
.B LIBKECCAK_GENERALISED_SPEC_ERROR_WORD_NONPOSITIVE
The specified word size is non-positive.
.TP
.B LIBKECCAK_GENERALISED_SPEC_ERROR_WORD_TOO_LARGE
The specified word size exceeded the supported limit
(currently at 64 bits.)
.TP
.B LIBKECCAK_GENERALISED_SPEC_ERROR_STATE_WORD_INCOHERENCY
The specified state size is not exactly 25 times larger
than the word size.
.TP
.B LIBKECCAK_GENERALISED_SPEC_ERROR_CAPACITY_NONPOSITIVE
The specified capacity was non-positive.
.TP
.B LIBKECCAK_GENERALISED_SPEC_ERROR_CAPACITY_MOD_8
The specified capacity was not equivalent to 0
modulus 8, that is, it was not in whole bytes.
.TP
.B LIBKECCAK_GENERALISED_SPEC_ERROR_BITRATE_NONPOSITIVE
The specified bitrate was non-positive.
.TP
.B LIBKECCAK_GENERALISED_SPEC_ERROR_BITRATE_MOD_8
The specified bitrate was not equivalent to 0
modulus 8, that is, it was not in whole bytes.
.TP
.B LIBKECCAK_GENERALISED_SPEC_ERROR_OUTPUT_NONPOSITIVE
The specified output size was non-positive.
.PP
Note that there may be more than one error. Only the first
detected is returned.
.SH ERRORS
The
.BR libkeccak_degeneralise_spec ()
function cannot fail.
.fi
.SH EXAMPLE
This examples configure a \fBlibkeccak_spec_t\fP to specify
settings for Keccak[c = 512]:
.LP
.nf
int r;
libkeccak_spec_t spec;
libkeccak_generalised_spec_t gspec;
libkeccak_generalised_spec_initialise(&gspec);
gspec.capacity = 512;
if ((r = libkeccak_degeneralise_spec(&gspec, &spec)))
    goto fail_degeneralise_spec;
if ((r = libkeccak_spec_check(&spec)));
    goto fail_spec_check;
.fi
.SH SEE ALSO
.BR libkeccak_generalised_spec_initialise (3),
.BR libkeccak_spec_check (3),
.BR libkeccak_spec_sha3 (3),
.BR libkeccak_spec_rawshake (3),
.BR libkeccak_spec_shake (3),
.BR libkeccak_state_initialise (3)
.SH AUTHORS
Principal author, Mattias Andrée.  See the LICENSE file for the full
list of authors.
.SH BUGS
Please report bugs to https://github.com/maandree/libkeccak/issues or to
maandree@member.fsf.org