LIBKECCAK_DEGENERALISE_SPEC(3)

NAME
libkeccak_degeneralise_spec - Set all specification parameters to automatic

SYNOPSIS
#include <libkeccak.h>
int libkeccak_degeneralise_spec(struct libkeccak_generalised_spec *spec, struct libkeccak_spec *output_spec);

Link with -lkeccak.

DESCRIPTION
The libkeccak_degeneralise_spec() function will resolve automatic parameters in *spec and translates the parameters to *output_spec, so that it can be used for hashing.

The function will modify both *spec and *output_spec.

You should call the libkeccak_spec_check(3) function after calling libkeccak_degeneralise_spec().

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) */
};

RETURN VALUES
The libkeccak_degeneralise_spec() function returns 0 if the settings are usable. Otherwise it will return one of the following constants.

LIBKECCAK_GENERALISED_SPEC_ERROR_STATE_NONPOSITIVE
    The specified state size is non-positive.

LIBKECCAK_GENERALISED_SPEC_ERROR_STATE_TOO_LARGE
    The specified state size exceeded the supported limit (currently at 1600 bits.)

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.

LIBKECCAK_GENERALISED_SPEC_ERROR_WORD_NONPOSITIVE
    The specified word size is non-positive.

LIBKECCAK_GENERALISED_SPEC_ERROR_WORD_TOO_LARGE
    The specified word size exceeded the supported limit (currently at 64 bits.)

LIBKECCAK_GENERALISED_SPEC_ERROR_STATE_WORD_INCOHERENCY
    The specified state size is not exactly 25 times larger than the word size.

LIBKECCAK_GENERALISED_SPEC_ERROR_CAPACITY_NONPOSITIVE
    The specified capacity was non-positive.

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.

LIBKECCAK_GENERALISED_SPEC_ERROR_BITRATE_NONPOSITIVE
    The specified bitrate was non-positive.

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.

LIBKECCAK_GENERALISED_SPEC_ERROR_OUTPUT_NONPOSITIVE
    The specified output size was non-positive.

Note that there may be more than one error. Only the first detected is returned.

ERRORS
The libkeccak_degeneralise_spec() function cannot fail.

EXAMPLE
This examples configure a struct libkeccak_spec to specify settings for Keccak[c = 512]:

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;

SEE ALSO
libkeccak_generalised_spec_initialise(3), libkeccak_spec_check(3), libkeccak_spec_sha3(3), libkeccak_spec_rawshake(3), libkeccak_spec_shake(3), libkeccak_state_initialise(3), libkeccak_hmac_initialise(3)