241 lines
9.6 KiB
C
241 lines
9.6 KiB
C
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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 "hash.h"
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#include "hash_state.h"
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#include "hashx4.h"
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#include "params.h"
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#include "thash.h"
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#include "thashx4.h"
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#include "utils.h"
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#include "wots.h"
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// TODO clarify address expectations, and make them more uniform.
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// TODO i.e. do we expect types to be set already?
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// TODO and do we expect modifications or copies?
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/**
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* Computes the starting value for a chain, i.e. the secret key.
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* Expects the address to be complete up to the chain address.
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*/
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static void wots_gen_sk(unsigned char *sk, const unsigned char *sk_seed,
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uint32_t wots_addr[8], const hash_state *state_seeded) {
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/* Make sure that the hash address is actually zeroed. */
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PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_set_hash_addr(wots_addr, 0);
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/* Generate sk element. */
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PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_prf_addr(sk, sk_seed, wots_addr, state_seeded);
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}
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/**
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* 4-way parallel version of wots_gen_sk; expects 4x as much space in sk
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*/
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static void wots_gen_skx4(unsigned char *skx4, const unsigned char *sk_seed,
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uint32_t wots_addrx4[4 * 8], const hash_state *state_seeded) {
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unsigned int j;
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/* Make sure that the hash address is actually zeroed. */
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for (j = 0; j < 4; j++) {
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PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_set_hash_addr(wots_addrx4 + j * 8, 0);
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}
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/* Generate sk element. */
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PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_prf_addrx4(skx4 + 0 * PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_N,
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skx4 + 1 * PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_N,
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skx4 + 2 * PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_N,
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skx4 + 3 * PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_N,
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sk_seed, wots_addrx4,
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state_seeded);
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}
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/**
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* Computes the chaining function.
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* out and in have to be n-byte arrays.
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*
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* Interprets in as start-th value of the chain.
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* addr has to contain the address of the chain.
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*/
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static void gen_chain(unsigned char *out, const unsigned char *in,
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unsigned int start, unsigned int steps,
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const unsigned char *pub_seed, uint32_t addr[8],
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const hash_state *state_seeded) {
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uint32_t i;
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/* Initialize out with the value at position 'start'. */
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memcpy(out, in, PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_N);
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/* Iterate 'steps' calls to the hash function. */
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for (i = start; i < (start + steps) && i < PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_WOTS_W; i++) {
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PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_set_hash_addr(addr, i);
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PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_thash_1(out, out, pub_seed, addr, state_seeded);
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}
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}
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/**
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* 4-way parallel version of gen_chain; expects 4x as much space in out, and
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* 4x as much space in inx4. Assumes start and step identical across chains.
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*/
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static void gen_chainx4(unsigned char *outx4, const unsigned char *inx4,
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unsigned int start, unsigned int steps,
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const unsigned char *pub_seed, uint32_t addrx4[4 * 8],
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const hash_state *state_seeded) {
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uint32_t i;
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unsigned int j;
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/* Initialize outx4 with the value at position 'start'. */
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memcpy(outx4, inx4, 4 * PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_N);
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/* Iterate 'steps' calls to the hash function. */
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for (i = start; i < (start + steps) && i < PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_WOTS_W; i++) {
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for (j = 0; j < 4; j++) {
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PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_set_hash_addr(addrx4 + j * 8, i);
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}
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PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_thashx4_1(outx4 + 0 * PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_N,
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outx4 + 1 * PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_N,
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outx4 + 2 * PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_N,
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outx4 + 3 * PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_N,
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outx4 + 0 * PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_N,
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outx4 + 1 * PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_N,
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outx4 + 2 * PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_N,
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outx4 + 3 * PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_N,
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pub_seed, addrx4,
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state_seeded);
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}
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}
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/**
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* base_w algorithm as described in draft.
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* Interprets an array of bytes as integers in base w.
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* This only works when log_w is a divisor of 8.
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*/
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static void base_w(unsigned int *output, const int out_len, const unsigned char *input) {
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int in = 0;
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int out = 0;
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unsigned char total = 0;
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int bits = 0;
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int consumed;
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for (consumed = 0; consumed < out_len; consumed++) {
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if (bits == 0) {
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total = input[in];
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in++;
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bits += 8;
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}
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bits -= PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_WOTS_LOGW;
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output[out] = (unsigned int)(total >> bits) & (PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_WOTS_W - 1);
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out++;
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}
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}
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/* Computes the WOTS+ checksum over a message (in base_w). */
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static void wots_checksum(unsigned int *csum_base_w, const unsigned int *msg_base_w) {
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unsigned int csum = 0;
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unsigned char csum_bytes[(PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_WOTS_LEN2 * PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_WOTS_LOGW + 7) / 8];
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unsigned int i;
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/* Compute checksum. */
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for (i = 0; i < PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_WOTS_LEN1; i++) {
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csum += PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_WOTS_W - 1 - msg_base_w[i];
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}
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/* Convert checksum to base_w. */
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/* Make sure expected empty zero bits are the least significant bits. */
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csum = csum << (8 - ((PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_WOTS_LEN2 * PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_WOTS_LOGW) % 8));
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PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_ull_to_bytes(csum_bytes, sizeof(csum_bytes), csum);
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base_w(csum_base_w, PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_WOTS_LEN2, csum_bytes);
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}
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/* Takes a message and derives the matching chain lengths. */
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static void chain_lengths(unsigned int *lengths, const unsigned char *msg) {
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base_w(lengths, PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_WOTS_LEN1, msg);
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wots_checksum(lengths + PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_WOTS_LEN1, lengths);
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}
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/**
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* WOTS key generation. Takes a 32 byte sk_seed, expands it to WOTS private key
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* elements and computes the corresponding public key.
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* It requires the seed pub_seed (used to generate bitmasks and hash keys)
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* and the address of this WOTS key pair.
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*
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* Writes the computed public key to 'pk'.
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*/
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void PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_wots_gen_pk(unsigned char *pk, const unsigned char *sk_seed,
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const unsigned char *pub_seed, uint32_t addr[8],
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const hash_state *state_seeded) {
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uint32_t i;
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unsigned int j;
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uint32_t addrx4[4 * 8];
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unsigned char pkbuf[4 * PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_N];
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for (j = 0; j < 4; j++) {
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memcpy(addrx4 + j * 8, addr, sizeof(uint32_t) * 8);
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}
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/* The last iteration typically does not have complete set of 4 chains,
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but because we use pkbuf, this is not an issue -- we still do as many
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in parallel as possible. */
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for (i = 0; i < ((PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_WOTS_LEN + 3) & ~0x3); i += 4) {
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for (j = 0; j < 4; j++) {
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PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_set_chain_addr(addrx4 + j * 8, i + j);
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}
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wots_gen_skx4(pkbuf, sk_seed, addrx4, state_seeded);
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gen_chainx4(pkbuf, pkbuf, 0, PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_WOTS_W - 1, pub_seed, addrx4, state_seeded);
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for (j = 0; j < 4; j++) {
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if (i + j < PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_WOTS_LEN) {
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memcpy(pk + (i + j)*PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_N, pkbuf + j * PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_N, PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_N);
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}
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}
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}
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// Get rid of unused argument variable.
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(void)state_seeded;
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}
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/**
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* Takes a n-byte message and the 32-byte sk_see to compute a signature 'sig'.
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*/
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void PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_wots_sign(unsigned char *sig, const unsigned char *msg,
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const unsigned char *sk_seed, const unsigned char *pub_seed,
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uint32_t addr[8], const hash_state *state_seeded) {
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unsigned int lengths[PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_WOTS_LEN];
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uint32_t i;
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chain_lengths(lengths, msg);
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for (i = 0; i < PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_WOTS_LEN; i++) {
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PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_set_chain_addr(addr, i);
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wots_gen_sk(sig + i * PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_N, sk_seed, addr, state_seeded);
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gen_chain(sig + i * PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_N, sig + i * PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_N, 0, lengths[i], pub_seed, addr, state_seeded);
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}
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// avoid unused argument
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(void)state_seeded;
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}
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/**
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* Takes a WOTS signature and an n-byte message, computes a WOTS public key.
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*
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* Writes the computed public key to 'pk'.
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*/
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void PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_wots_pk_from_sig(unsigned char *pk,
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const unsigned char *sig, const unsigned char *msg,
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const unsigned char *pub_seed, uint32_t addr[8],
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const hash_state *state_seeded) {
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unsigned int lengths[PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_WOTS_LEN];
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uint32_t i;
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chain_lengths(lengths, msg);
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for (i = 0; i < PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_WOTS_LEN; i++) {
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PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_set_chain_addr(addr, i);
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gen_chain(pk + i * PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_N, sig + i * PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_N,
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lengths[i], PQCLEAN_SPHINCSSHAKE256256SROBUST_AVX2_WOTS_W - 1 - lengths[i], pub_seed, addr,
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state_seeded);
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}
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// avoid unused argument
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(void)state_seeded;
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}
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