NAME¶

libkeccak_spec_check - Validate hashing parameters

SYNOPSIS¶

#include <libkeccak.h>
int libkeccak_spec_check(const struct libkeccak_spec *spec);

Link with -lkeccak.

DESCRIPTION¶

The libkeccak_spec_check() function validates the parameters of *spec, so that unusable configurations can be detected. It is recommended to call this function after calling libkeccak_spec_sha3(3), libkeccak_spec_cshake(3), libkeccak_spec_rawshake(3), libkeccak_spec_shake(3), or, especially, after settings the parameters manually for Keccak hashing.

struct libkeccak_spec {
	long int bitrate;  /* bitrate (in bits) */
	long int capacity; /* capacity (in bits) */
	long int output;   /* output size (in bits) */
};

RETURN VALUES¶

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

LIBKECCAK_SPEC_ERROR_BITRATE_NONPOSITIVE

The specified bitrate was non-positive.

LIBKECCAK_SPEC_ERROR_BITRATE_MOD_8

The specified bitrate was not equivalent to 0 modulus 8, that is, it was not in whole bytes.

LIBKECCAK_SPEC_ERROR_CAPACITY_NONPOSITIVE

The specified capacity was non-positive.

LIBKECCAK_SPEC_ERROR_CAPACITY_MOD_8

The specified capacity was not equivalent to 0 modulus 8, that is, it was not in whole bytes.

LIBKECCAK_SPEC_ERROR_OUTPUT_NONPOSITIVE

The specified output size was non-positive.

LIBKECCAK_SPEC_ERROR_STATE_TOO_LARGE

The state size, that is the sum of the bitrate and the capacity, exceeded the supported limit (currently at 1600 bits.)

LIBKECCAK_SPEC_ERROR_STATE_MOD_25

The state size, that is the sum of the bitrate and the capacity, in bits, was not equivalent to 0 modulus 25. Meaning the state size cannot cover all lanes equivalently.

LIBKECCAK_SPEC_ERROR_WORD_NON_2_POTENT

The word size, that is the state size divided by 25, is not a power of 2.

LIBKECCAK_SPEC_ERROR_WORD_MOD_8

The word size, that is the state size divided by 25, is not quivalent to 0 modulus 8, that is, it is not in whole bytes.

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

ERRORS¶

The libkeccak_spec_check() function cannot fail.

SEE ALSO¶

libkeccak_spec_sha3(3), libkeccak_spec_cshake(3), libkeccak_spec_rawshake(3), libkeccak_spec_shake(3), libkeccak_generalised_spec_initialise(3), libkeccak_state_initialise(3), libkeccak_hmac_initialise(3)