354 lines
12 KiB
C
354 lines
12 KiB
C
#include <stddef.h>
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#include <stdint.h>
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#include <string.h>
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#include "address.h"
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#include "api.h"
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#include "fors.h"
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#include "hash.h"
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#include "hash_state.h"
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#include "params.h"
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#include "randombytes.h"
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#include "thash.h"
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#include "utils.h"
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#include "wots.h"
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/**
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* Computes the leaf at a given address. First generates the WOTS key pair,
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* then computes leaf by hashing horizontally.
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*/
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static void wots_gen_leaf(unsigned char *leaf, const unsigned char *sk_seed,
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const unsigned char *pub_seed,
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uint32_t addr_idx, const uint32_t tree_addr[8],
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const hash_state *hash_state_seeded) {
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unsigned char pk[SPX_WOTS_BYTES];
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uint32_t wots_addr[8] = {0};
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uint32_t wots_pk_addr[8] = {0};
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_set_type(
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wots_addr, SPX_ADDR_TYPE_WOTS);
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_set_type(
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wots_pk_addr, SPX_ADDR_TYPE_WOTSPK);
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_copy_subtree_addr(
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wots_addr, tree_addr);
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_set_keypair_addr(
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wots_addr, addr_idx);
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_wots_gen_pk(
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pk, sk_seed, pub_seed, wots_addr, hash_state_seeded);
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_copy_keypair_addr(
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wots_pk_addr, wots_addr);
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_thash_WOTS_LEN(
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leaf, pk, pub_seed, wots_pk_addr, hash_state_seeded);
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}
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/*
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* Returns the length of a secret key, in bytes
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*/
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size_t PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_crypto_sign_secretkeybytes(void) {
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return PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_CRYPTO_SECRETKEYBYTES;
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}
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/*
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* Returns the length of a public key, in bytes
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*/
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size_t PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_crypto_sign_publickeybytes(void) {
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return PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_CRYPTO_PUBLICKEYBYTES;
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}
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/*
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* Returns the length of a signature, in bytes
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*/
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size_t PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_crypto_sign_bytes(void) {
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return PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_CRYPTO_BYTES;
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}
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/*
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* Returns the length of the seed required to generate a key pair, in bytes
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*/
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size_t PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_crypto_sign_seedbytes(void) {
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return PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_CRYPTO_SEEDBYTES;
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}
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/*
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* Generates an SPX key pair given a seed of length
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* Format sk: [SK_SEED || SK_PRF || PUB_SEED || root]
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* Format pk: [PUB_SEED || root]
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*/
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int PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_crypto_sign_seed_keypair(
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uint8_t *pk, uint8_t *sk, const uint8_t *seed) {
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/* We do not need the auth path in key generation, but it simplifies the
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code to have just one treehash routine that computes both root and path
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in one function. */
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unsigned char auth_path[SPX_TREE_HEIGHT * SPX_N];
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uint32_t top_tree_addr[8] = {0};
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hash_state hash_state_seeded;
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_set_layer_addr(
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top_tree_addr, SPX_D - 1);
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_set_type(
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top_tree_addr, SPX_ADDR_TYPE_HASHTREE);
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/* Initialize SK_SEED, SK_PRF and PUB_SEED from seed. */
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memcpy(sk, seed, PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_CRYPTO_SEEDBYTES);
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memcpy(pk, sk + 2 * SPX_N, SPX_N);
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/* This hook allows the hash function instantiation to do whatever
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preparation or computation it needs, based on the public seed. */
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_initialize_hash_function(&hash_state_seeded, pk, sk);
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/* Compute root node of the top-most subtree. */
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_treehash_TREE_HEIGHT(
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sk + 3 * SPX_N, auth_path, sk, sk + 2 * SPX_N, 0, 0,
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wots_gen_leaf, top_tree_addr, &hash_state_seeded);
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memcpy(pk + SPX_N, sk + 3 * SPX_N, SPX_N);
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return 0;
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}
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/*
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* Generates an SPX key pair.
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* Format sk: [SK_SEED || SK_PRF || PUB_SEED || root]
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* Format pk: [PUB_SEED || root]
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*/
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int PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_crypto_sign_keypair(
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uint8_t *pk, uint8_t *sk) {
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unsigned char seed[PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_CRYPTO_SEEDBYTES];
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randombytes(seed, PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_CRYPTO_SEEDBYTES);
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_crypto_sign_seed_keypair(
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pk, sk, seed);
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return 0;
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}
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/**
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* Returns an array containing a detached signature.
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*/
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int PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_crypto_sign_signature(
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uint8_t *sig, size_t *siglen,
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const uint8_t *m, size_t mlen, const uint8_t *sk) {
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const unsigned char *sk_seed = sk;
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const unsigned char *sk_prf = sk + SPX_N;
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const unsigned char *pk = sk + 2 * SPX_N;
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const unsigned char *pub_seed = pk;
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unsigned char optrand[SPX_N];
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unsigned char mhash[SPX_FORS_MSG_BYTES];
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unsigned char root[SPX_N];
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uint32_t i;
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uint64_t tree;
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uint32_t idx_leaf;
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uint32_t wots_addr[8] = {0};
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uint32_t tree_addr[8] = {0};
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hash_state hash_state_seeded;
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/* This hook allows the hash function instantiation to do whatever
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preparation or computation it needs, based on the public seed. */
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_initialize_hash_function(
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&hash_state_seeded,
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pub_seed, sk_seed);
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_set_type(
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wots_addr, SPX_ADDR_TYPE_WOTS);
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_set_type(
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tree_addr, SPX_ADDR_TYPE_HASHTREE);
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/* Optionally, signing can be made non-deterministic using optrand.
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This can help counter side-channel attacks that would benefit from
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getting a large number of traces when the signer uses the same nodes. */
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randombytes(optrand, SPX_N);
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/* Compute the digest randomization value. */
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_gen_message_random(
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sig, sk_prf, optrand, m, mlen, &hash_state_seeded);
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/* Derive the message digest and leaf index from R, PK and M. */
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_hash_message(
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mhash, &tree, &idx_leaf, sig, pk, m, mlen, &hash_state_seeded);
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sig += SPX_N;
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_set_tree_addr(wots_addr, tree);
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_set_keypair_addr(
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wots_addr, idx_leaf);
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/* Sign the message hash using FORS. */
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_fors_sign(
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sig, root, mhash, sk_seed, pub_seed, wots_addr, &hash_state_seeded);
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sig += SPX_FORS_BYTES;
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for (i = 0; i < SPX_D; i++) {
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_set_layer_addr(tree_addr, i);
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_set_tree_addr(tree_addr, tree);
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_copy_subtree_addr(
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wots_addr, tree_addr);
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_set_keypair_addr(
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wots_addr, idx_leaf);
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/* Compute a WOTS signature. */
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_wots_sign(
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sig, root, sk_seed, pub_seed, wots_addr, &hash_state_seeded);
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sig += SPX_WOTS_BYTES;
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/* Compute the authentication path for the used WOTS leaf. */
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_treehash_TREE_HEIGHT(
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root, sig, sk_seed, pub_seed, idx_leaf, 0,
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wots_gen_leaf, tree_addr, &hash_state_seeded);
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sig += SPX_TREE_HEIGHT * SPX_N;
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/* Update the indices for the next layer. */
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idx_leaf = (tree & ((1 << SPX_TREE_HEIGHT) - 1));
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tree = tree >> SPX_TREE_HEIGHT;
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}
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*siglen = SPX_BYTES;
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return 0;
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}
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/**
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* Verifies a detached signature and message under a given public key.
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*/
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int PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_crypto_sign_verify(
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const uint8_t *sig, size_t siglen,
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const uint8_t *m, size_t mlen, const uint8_t *pk) {
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const unsigned char *pub_seed = pk;
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const unsigned char *pub_root = pk + SPX_N;
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unsigned char mhash[SPX_FORS_MSG_BYTES];
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unsigned char wots_pk[SPX_WOTS_BYTES];
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unsigned char root[SPX_N];
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unsigned char leaf[SPX_N];
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unsigned int i;
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uint64_t tree;
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uint32_t idx_leaf;
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uint32_t wots_addr[8] = {0};
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uint32_t tree_addr[8] = {0};
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uint32_t wots_pk_addr[8] = {0};
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hash_state hash_state_seeded;
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if (siglen != SPX_BYTES) {
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return -1;
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}
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/* This hook allows the hash function instantiation to do whatever
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preparation or computation it needs, based on the public seed. */
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_initialize_hash_function(
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&hash_state_seeded,
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pub_seed, NULL);
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_set_type(
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wots_addr, SPX_ADDR_TYPE_WOTS);
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_set_type(
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tree_addr, SPX_ADDR_TYPE_HASHTREE);
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_set_type(
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wots_pk_addr, SPX_ADDR_TYPE_WOTSPK);
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/* Derive the message digest and leaf index from R || PK || M. */
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/* The additional SPX_N is a result of the hash domain separator. */
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_hash_message(
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mhash, &tree, &idx_leaf, sig, pk, m, mlen, &hash_state_seeded);
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sig += SPX_N;
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/* Layer correctly defaults to 0, so no need to set_layer_addr */
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_set_tree_addr(wots_addr, tree);
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_set_keypair_addr(
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wots_addr, idx_leaf);
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_fors_pk_from_sig(
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root, sig, mhash, pub_seed, wots_addr, &hash_state_seeded);
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sig += SPX_FORS_BYTES;
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/* For each subtree.. */
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for (i = 0; i < SPX_D; i++) {
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_set_layer_addr(tree_addr, i);
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_set_tree_addr(tree_addr, tree);
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_copy_subtree_addr(
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wots_addr, tree_addr);
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_set_keypair_addr(
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wots_addr, idx_leaf);
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_copy_keypair_addr(
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wots_pk_addr, wots_addr);
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/* The WOTS public key is only correct if the signature was correct. */
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/* Initially, root is the FORS pk, but on subsequent iterations it is
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the root of the subtree below the currently processed subtree. */
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_wots_pk_from_sig(
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wots_pk, sig, root, pub_seed, wots_addr, &hash_state_seeded);
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sig += SPX_WOTS_BYTES;
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/* Compute the leaf node using the WOTS public key. */
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_thash_WOTS_LEN(
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leaf, wots_pk, pub_seed, wots_pk_addr, &hash_state_seeded);
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/* Compute the root node of this subtree. */
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_compute_root(
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root, leaf, idx_leaf, 0, sig, SPX_TREE_HEIGHT,
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pub_seed, tree_addr, &hash_state_seeded);
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sig += SPX_TREE_HEIGHT * SPX_N;
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/* Update the indices for the next layer. */
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idx_leaf = (tree & ((1 << SPX_TREE_HEIGHT) - 1));
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tree = tree >> SPX_TREE_HEIGHT;
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}
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/* Check if the root node equals the root node in the public key. */
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if (memcmp(root, pub_root, SPX_N) != 0) {
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return -1;
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}
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return 0;
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}
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/**
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* Returns an array containing the signature followed by the message.
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*/
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int PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_crypto_sign(
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uint8_t *sm, size_t *smlen,
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const uint8_t *m, size_t mlen, const uint8_t *sk) {
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size_t siglen;
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PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_crypto_sign_signature(
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sm, &siglen, m, mlen, sk);
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memmove(sm + SPX_BYTES, m, mlen);
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*smlen = siglen + mlen;
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return 0;
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}
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/**
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* Verifies a given signature-message pair under a given public key.
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*/
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int PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_crypto_sign_open(
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uint8_t *m, size_t *mlen,
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const uint8_t *sm, size_t smlen, const uint8_t *pk) {
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/* The API caller does not necessarily know what size a signature should be
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but SPHINCS+ signatures are always exactly SPX_BYTES. */
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if (smlen < SPX_BYTES) {
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memset(m, 0, smlen);
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*mlen = 0;
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return -1;
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}
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*mlen = smlen - SPX_BYTES;
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if (PQCLEAN_SPHINCSHARAKA256FROBUST_CLEAN_crypto_sign_verify(
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sm, SPX_BYTES, sm + SPX_BYTES, *mlen, pk)) {
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memset(m, 0, smlen);
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*mlen = 0;
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return -1;
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}
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/* If verification was successful, move the message to the right place. */
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memmove(m, sm + SPX_BYTES, *mlen);
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return 0;
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}
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