cx_mlkem_util.c File Reference

ML-KEM utility functions (FIPS 203). More...

#include <string.h>
#include "lcx_mlkem.h"
#include "cx_mlkem_util.h"
#include "lcx_sha3.h"

Include dependency graph for cx_mlkem_util.c:

Go to the source code of this file.

Functions
void	MLKEM_UTIL_hash_h (uint8_t out[CX_SHA3_256_SIZE], const uint8_t *in, size_t in_len)
	Computes the H hash function (SHA3-256) as defined in FIPS 203.
void	MLKEM_UTIL_hash_g (uint8_t *out, const uint8_t *in, size_t in_len)
	Computes the G hash function (SHA3-512) as defined in FIPS 203.
void	MLKEM_UTIL_hash_j (uint8_t *out, const uint8_t *in, size_t inlen)
void	MLKEM_UTIL_prf (uint8_t *out, size_t outlen, const uint8_t *key, uint8_t nonce)
	Computes the PRF function (SHAKE256) as defined in FIPS 203.
void	MLKEM_UTIL_xof_squeeze (uint8_t *out, size_t outlen, const uint8_t *seed, uint8_t x, uint8_t y)
	Computes the XOF function (SHAKE128) as defined in FIPS 203.
void	MLKEM_UTIL_ct_cmov (uint8_t *dst, const uint8_t *src, size_t len, uint8_t b)
cx_err_t	MLKEM_UTIL_check_ek (const uint8_t *ek, const MLKEM_param_info_t *p)
	Validates encapsulation key modulus (FIPS 203 §7.2).

Detailed Description

ML-KEM utility functions (FIPS 203).

Implements the hash functions H (SHA3-256) and G (SHA3-512), the PRF (SHAKE256), the XOF (SHAKE128) used throughout the ML-KEM implementation.

Definition in file cx_mlkem_util.c.

Function Documentation

MLKEM_UTIL_check_ek()

cx_err_t MLKEM_UTIL_check_ek	(	const uint8_t *	ek,
		const MLKEM_param_info_t *	p
	)

Validates encapsulation key modulus (FIPS 203 §7.2).

Verifies that every 12-bit decoded coefficient of the public polynomial vector is in [0, q-1].

Parameters

[in]	ek	Encapsulation key bytes (polynomial vector portion).
[in]	p	ML-KEM parameter set.

Returns

cx_err_t

Return values

CX_OK	ek is valid
CX_INVALID_PARAMETER	ek is not valid.

Definition at line 71 of file cx_mlkem_util.c.

MLKEM_UTIL_ct_cmov()

void MLKEM_UTIL_ct_cmov	(	uint8_t *	dst,
		const uint8_t *	src,
		size_t	len,
		uint8_t	b
	)

Definition at line 63 of file cx_mlkem_util.c.

MLKEM_UTIL_hash_g()

void MLKEM_UTIL_hash_g	(	uint8_t *	out,
		const uint8_t *	in,
		size_t	in_len
	)

Computes the G hash function (SHA3-512) as defined in FIPS 203.

Parameters

[out]	out	Output buffer of at least 64 bytes.
[in]	in	Input data to hash.
[in]	in_len	Length of the input data in bytes.

Definition at line 35 of file cx_mlkem_util.c.

MLKEM_UTIL_hash_h()

void MLKEM_UTIL_hash_h	(	uint8_t	out[CX_SHA3_256_SIZE],
		const uint8_t *	in,
		size_t	in_len
	)

Computes the H hash function (SHA3-256) as defined in FIPS 203.

Parameters

[out]	out	Output buffer of size CX_SHA3_256_SIZE bytes.
[in]	in	Input data to hash.
[in]	in_len	Length of the input data in bytes.

Definition at line 30 of file cx_mlkem_util.c.

MLKEM_UTIL_hash_j()

void MLKEM_UTIL_hash_j	(	uint8_t *	out,
		const uint8_t *	in,
		size_t	inlen
	)

Definition at line 40 of file cx_mlkem_util.c.

MLKEM_UTIL_prf()

void MLKEM_UTIL_prf	(	uint8_t *	out,
		size_t	outlen,
		const uint8_t *	key,
		uint8_t	nonce
	)

Computes the PRF function (SHAKE256) as defined in FIPS 203.

Parameters

[out]	out	Output buffer.
[in]	outlen	Number of bytes to produce.
[in]	key	Input key of MLKEM_SYMBYTES bytes.
[in]	nonce	Single-byte nonce appended to the key.

Definition at line 45 of file cx_mlkem_util.c.

MLKEM_UTIL_xof_squeeze()

void MLKEM_UTIL_xof_squeeze	(	uint8_t *	out,
		size_t	outlen,
		const uint8_t *	seed,
		uint8_t	x,
		uint8_t	y
	)

Computes the XOF function (SHAKE128) as defined in FIPS 203.

Parameters

[out]	out	Output buffer.
[in]	outlen	Number of bytes to produce.
[in]	seed	Input seed of MLKEM_SYMBYTES bytes.
[in]	x	First index byte appended to the seed.
[in]	y	Second index byte appended to the seed.

Definition at line 54 of file cx_mlkem_util.c.