.TH LIBKECCAK_DEGENERALISE_SPEC 3 LIBKECCAK
.SH NAME
libkeccak_degeneralise_spec - Set all specification parameters to automatic
.SH SYNOPSIS
.nf
#include <libkeccak.h>

int libkeccak_degeneralise_spec(struct libkeccak_generalised_spec *\fIspec\fP, struct libkeccak_spec *\fIoutput_spec\fP);
.fi
.PP
Link with
.IR -lkeccak .
.SH DESCRIPTION
The
.BR libkeccak_degeneralise_spec ()
function will resolve automatic parameters in
.I *spec
and translates the parameters to
.IR *output_spec ,
so that it can be used for hashing.
.PP
The function will modify both
.I *spec
and
.IR *output_spec .
.PP
You should call the
.BR libkeccak_spec_check (3)
function after calling
.BR libkeccak_degeneralise_spec ().
.PP
.nf
struct libkeccak_generalised_spec {
	long int bitrate;    /* bitrate (in bits) */
	long int capacity;   /* capacity (in bits) */
	long int output;     /* output size (in bits) */
	long int state_size; /* state size (in bits) */
	long int word_size;  /* word size (in bits) */
};
.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
.B struct libkeccak_spec
to specify settings for Keccak[c = 512]:
.PP
.nf
int r;
struct libkeccak_spec spec;
struct libkeccak_generalised_spec 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),
.BR libkeccak_hmac_initialise (3)