/**
* \file lmots.h
*
* \brief This file provides an API for the LM-OTS post-quantum-safe one-time
* public-key signature scheme as defined in RFC8554 and NIST.SP.200-208.
* This implementation currently only supports a single parameter set
* MBEDTLS_LMOTS_SHA256_N32_W8 in order to reduce complexity.
*/
/*
* Copyright The Mbed TLS Contributors
* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
*/
#ifndef MBEDTLS_LMOTS_H
#define MBEDTLS_LMOTS_H
#include "mbedtls/build_info.h"
#include "psa/crypto.h"
#include "mbedtls/lms.h"
#include <stdint.h>
#include <stddef.h>
#define MBEDTLS_LMOTS_PUBLIC_KEY_LEN(type) (MBEDTLS_LMOTS_TYPE_LEN + \
MBEDTLS_LMOTS_I_KEY_ID_LEN + \
MBEDTLS_LMOTS_Q_LEAF_ID_LEN + \
MBEDTLS_LMOTS_N_HASH_LEN(type))
#define MBEDTLS_LMOTS_SIG_TYPE_OFFSET (0)
#define MBEDTLS_LMOTS_SIG_C_RANDOM_OFFSET (MBEDTLS_LMOTS_SIG_TYPE_OFFSET + \
MBEDTLS_LMOTS_TYPE_LEN)
#define MBEDTLS_LMOTS_SIG_SIGNATURE_OFFSET(type) (MBEDTLS_LMOTS_SIG_C_RANDOM_OFFSET + \
MBEDTLS_LMOTS_C_RANDOM_VALUE_LEN(type))
#ifdef __cplusplus
extern "C" {
#endif
#if defined(MBEDTLS_TEST_HOOKS)
extern int (*mbedtls_lmots_sign_private_key_invalidated_hook)(unsigned char *);
#endif /* defined(MBEDTLS_TEST_HOOKS) */
#if !defined(MBEDTLS_DEPRECATED_REMOVED)
/**
* \brief This function converts a \ref psa_status_t to a
* low-level LMS error code.
*
* \param status The psa_status_t to convert
*
* \return The corresponding LMS error code.
*/
int MBEDTLS_DEPRECATED mbedtls_lms_error_from_psa(psa_status_t status);
#endif
/**
* \brief This function initializes a public LMOTS context
*
* \param ctx The uninitialized LMOTS context that will then be
* initialized.
*/
void mbedtls_lmots_public_init(mbedtls_lmots_public_t *ctx);
/**
* \brief This function uninitializes a public LMOTS context
*
* \param ctx The initialized LMOTS context that will then be
* uninitialized.
*/
void mbedtls_lmots_public_free(mbedtls_lmots_public_t *ctx);
/**
* \brief This function imports an LMOTS public key into a
* LMOTS context.
*
* \note Before this function is called, the context must
* have been initialized.
*
* \note See IETF RFC8554 for details of the encoding of
* this public key.
*
* \param ctx The initialized LMOTS context store the key in.
* \param key The buffer from which the key will be read.
* #MBEDTLS_LMOTS_PUBLIC_KEY_LEN bytes will be read
* from this.
*
* \return \c 0 on success.
* \return A non-zero error code on failure.
*/
int mbedtls_lmots_import_public_key(mbedtls_lmots_public_t *ctx,
const unsigned char *key, size_t key_size);
/**
* \brief This function exports an LMOTS public key from a
* LMOTS context that already contains a public key.
*
* \note Before this function is called, the context must
* have been initialized and the context must contain
* a public key.
*
* \note See IETF RFC8554 for details of the encoding of
* this public key.
*
* \param ctx The initialized LMOTS context that contains the
* public key.
* \param key The buffer into which the key will be output. Must
* be at least #MBEDTLS_LMOTS_PUBLIC_KEY_LEN in size.
*
* \return \c 0 on success.
* \return A non-zero error code on failure.
*/
int mbedtls_lmots_export_public_key(const mbedtls_lmots_public_t *ctx,
unsigned char *key, size_t key_size,
size_t *key_len);
/**
* \brief This function creates a candidate public key from
* an LMOTS signature. This can then be compared to
* the real public key to determine the validity of
* the signature.
*
* \note This function is exposed publicly to be used in LMS
* signature verification, it is expected that
* mbedtls_lmots_verify will be used for LMOTS
* signature verification.
*
* \param params The LMOTS parameter set, q and I values as an
* mbedtls_lmots_parameters_t struct.
* \param msg The buffer from which the message will be read.
* \param msg_size The size of the message that will be read.
* \param sig The buffer from which the signature will be read.
* #MBEDTLS_LMOTS_SIG_LEN bytes will be read from
* this.
* \param out The buffer where the candidate public key will be
* stored. Must be at least #MBEDTLS_LMOTS_N_HASH_LEN
* bytes in size.
*
* \return \c 0 on success.
* \return A non-zero error code on failure.
*/
int mbedtls_lmots_calculate_public_key_candidate(const mbedtls_lmots_parameters_t *params,
const unsigned char *msg,
size_t msg_size,
const unsigned char *sig,
size_t sig_size,
unsigned char *out,
size_t out_size,
size_t *out_len);
/**
* \brief This function verifies a LMOTS signature, using a
* LMOTS context that contains a public key.
*
* \warning This function is **not intended for use in
* production**, due to as-yet unsolved problems with
* handling stateful keys. The API for this function
* may change considerably in future versions.
*
* \note Before this function is called, the context must
* have been initialized and must contain a public key
* (either by import or calculation from a private
* key).
*
* \param ctx The initialized LMOTS context from which the public
* key will be read.
* \param msg The buffer from which the message will be read.
* \param msg_size The size of the message that will be read.
* \param sig The buf from which the signature will be read.
* #MBEDTLS_LMOTS_SIG_LEN bytes will be read from
* this.
*
* \return \c 0 on successful verification.
* \return A non-zero error code on failure.
*/
int mbedtls_lmots_verify(const mbedtls_lmots_public_t *ctx,
const unsigned char *msg,
size_t msg_size, const unsigned char *sig,
size_t sig_size);
#if defined(MBEDTLS_LMS_PRIVATE)
/**
* \brief This function initializes a private LMOTS context
*
* \param ctx The uninitialized LMOTS context that will then be
* initialized.
*/
void mbedtls_lmots_private_init(mbedtls_lmots_private_t *ctx);
/**
* \brief This function uninitializes a private LMOTS context
*
* \param ctx The initialized LMOTS context that will then be
* uninitialized.
*/
void mbedtls_lmots_private_free(mbedtls_lmots_private_t *ctx);
/**
* \brief This function calculates an LMOTS private key, and
* stores in into an LMOTS context.
*
* \warning This function is **not intended for use in
* production**, due to as-yet unsolved problems with
* handling stateful keys. The API for this function
* may change considerably in future versions.
*
* \note The seed must have at least 256 bits of entropy.
*
* \param ctx The initialized LMOTS context to generate the key
* into.
* \param I_key_identifier The key identifier of the key, as a 16-byte string.
* \param q_leaf_identifier The leaf identifier of key. If this LMOTS key is
* not being used as part of an LMS key, this should
* be set to 0.
* \param seed The seed used to deterministically generate the
* key.
* \param seed_size The length of the seed.
*
* \return \c 0 on success.
* \return A non-zero error code on failure.
*/
int mbedtls_lmots_generate_private_key(mbedtls_lmots_private_t *ctx,
mbedtls_lmots_algorithm_type_t type,
const unsigned char I_key_identifier[MBEDTLS_LMOTS_I_KEY_ID_LEN],
uint32_t q_leaf_identifier,
const unsigned char *seed,
size_t seed_size);
/**
* \brief This function generates an LMOTS public key from a
* LMOTS context that already contains a private key.
*
* \note Before this function is called, the context must
* have been initialized and the context must contain
* a private key.
*
* \param ctx The initialized LMOTS context to generate the key
* from and store it into.
*
* \return \c 0 on success.
* \return A non-zero error code on failure.
*/
int mbedtls_lmots_calculate_public_key(mbedtls_lmots_public_t *ctx,
const mbedtls_lmots_private_t *priv_ctx);
/**
* \brief This function creates a LMOTS signature, using a
* LMOTS context that contains a private key.
*
* \note Before this function is called, the context must
* have been initialized and must contain a private
* key.
*
* \note LMOTS private keys can only be used once, otherwise
* attackers may be able to create forged signatures.
* If the signing operation is successful, the private
* key in the context will be erased, and no further
* signing will be possible until another private key
* is loaded
*
* \param ctx The initialized LMOTS context from which the
* private key will be read.
* \param f_rng The RNG function to be used for signature
* generation.
* \param p_rng The RNG context to be passed to f_rng
* \param msg The buffer from which the message will be read.
* \param msg_size The size of the message that will be read.
* \param sig The buf into which the signature will be stored.
* Must be at least #MBEDTLS_LMOTS_SIG_LEN in size.
*
* \return \c 0 on success.
* \return A non-zero error code on failure.
*/
int mbedtls_lmots_sign(mbedtls_lmots_private_t *ctx,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng, const unsigned char *msg, size_t msg_size,
unsigned char *sig, size_t sig_size, size_t *sig_len);
#endif /* defined(MBEDTLS_LMS_PRIVATE) */
#ifdef __cplusplus
}
#endif
#endif /* MBEDTLS_LMOTS_H */