facb527c7c
* Add state destroy to SHA2 API * Include optimized SPHINCS+ implementations I've generated new implementations from the sphincsplus repository. * Don't destroy sha256ctx after finalize * Attempt to shut up MSVC * Make sure to drop errors in rmtree
168 lines
6.5 KiB
C
168 lines
6.5 KiB
C
#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 "params.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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// 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],
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const hash_state *hash_state_seeded) {
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/* Make sure that the hash address is actually zeroed. */
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PQCLEAN_SPHINCSSHA256192SSIMPLE_CLEAN_set_hash_addr(wots_addr, 0);
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/* Generate sk element. */
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PQCLEAN_SPHINCSSHA256192SSIMPLE_CLEAN_prf_addr(sk, sk_seed, wots_addr, hash_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 *hash_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_SPHINCSSHA256192SSIMPLE_CLEAN_N);
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/* Iterate 'steps' calls to the hash function. */
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for (i = start; i < (start + steps) && i < PQCLEAN_SPHINCSSHA256192SSIMPLE_CLEAN_WOTS_W; i++) {
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PQCLEAN_SPHINCSSHA256192SSIMPLE_CLEAN_set_hash_addr(addr, i);
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PQCLEAN_SPHINCSSHA256192SSIMPLE_CLEAN_thash_1(
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out, out, pub_seed, addr, hash_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 size_t out_len,
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const unsigned char *input) {
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size_t in = 0;
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size_t out = 0;
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unsigned char total = 0;
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unsigned int bits = 0;
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size_t 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_SPHINCSSHA256192SSIMPLE_CLEAN_WOTS_LOGW;
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output[out] = (unsigned int)((total >> bits) & (PQCLEAN_SPHINCSSHA256192SSIMPLE_CLEAN_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,
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const unsigned int *msg_base_w) {
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unsigned int csum = 0;
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unsigned char csum_bytes[(PQCLEAN_SPHINCSSHA256192SSIMPLE_CLEAN_WOTS_LEN2 * PQCLEAN_SPHINCSSHA256192SSIMPLE_CLEAN_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_SPHINCSSHA256192SSIMPLE_CLEAN_WOTS_LEN1; i++) {
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csum += PQCLEAN_SPHINCSSHA256192SSIMPLE_CLEAN_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_SPHINCSSHA256192SSIMPLE_CLEAN_WOTS_LEN2 * PQCLEAN_SPHINCSSHA256192SSIMPLE_CLEAN_WOTS_LOGW) % 8));
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PQCLEAN_SPHINCSSHA256192SSIMPLE_CLEAN_ull_to_bytes(
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csum_bytes, sizeof(csum_bytes), csum);
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base_w(csum_base_w, PQCLEAN_SPHINCSSHA256192SSIMPLE_CLEAN_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_SPHINCSSHA256192SSIMPLE_CLEAN_WOTS_LEN1, msg);
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wots_checksum(lengths + PQCLEAN_SPHINCSSHA256192SSIMPLE_CLEAN_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_SPHINCSSHA256192SSIMPLE_CLEAN_wots_gen_pk(
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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 *hash_state_seeded) {
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uint32_t i;
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for (i = 0; i < PQCLEAN_SPHINCSSHA256192SSIMPLE_CLEAN_WOTS_LEN; i++) {
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PQCLEAN_SPHINCSSHA256192SSIMPLE_CLEAN_set_chain_addr(addr, i);
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wots_gen_sk(pk + i * PQCLEAN_SPHINCSSHA256192SSIMPLE_CLEAN_N, sk_seed, addr, hash_state_seeded);
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gen_chain(pk + i * PQCLEAN_SPHINCSSHA256192SSIMPLE_CLEAN_N, pk + i * PQCLEAN_SPHINCSSHA256192SSIMPLE_CLEAN_N,
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0, PQCLEAN_SPHINCSSHA256192SSIMPLE_CLEAN_WOTS_W - 1, pub_seed, addr, hash_state_seeded);
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}
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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_SPHINCSSHA256192SSIMPLE_CLEAN_wots_sign(
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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 *hash_state_seeded) {
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unsigned int lengths[PQCLEAN_SPHINCSSHA256192SSIMPLE_CLEAN_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_SPHINCSSHA256192SSIMPLE_CLEAN_WOTS_LEN; i++) {
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PQCLEAN_SPHINCSSHA256192SSIMPLE_CLEAN_set_chain_addr(addr, i);
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wots_gen_sk(sig + i * PQCLEAN_SPHINCSSHA256192SSIMPLE_CLEAN_N, sk_seed, addr, hash_state_seeded);
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gen_chain(sig + i * PQCLEAN_SPHINCSSHA256192SSIMPLE_CLEAN_N, sig + i * PQCLEAN_SPHINCSSHA256192SSIMPLE_CLEAN_N, 0, lengths[i], pub_seed, addr, hash_state_seeded);
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}
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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_SPHINCSSHA256192SSIMPLE_CLEAN_wots_pk_from_sig(
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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 *hash_state_seeded) {
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unsigned int lengths[PQCLEAN_SPHINCSSHA256192SSIMPLE_CLEAN_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_SPHINCSSHA256192SSIMPLE_CLEAN_WOTS_LEN; i++) {
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PQCLEAN_SPHINCSSHA256192SSIMPLE_CLEAN_set_chain_addr(addr, i);
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gen_chain(pk + i * PQCLEAN_SPHINCSSHA256192SSIMPLE_CLEAN_N, sig + i * PQCLEAN_SPHINCSSHA256192SSIMPLE_CLEAN_N,
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lengths[i], PQCLEAN_SPHINCSSHA256192SSIMPLE_CLEAN_WOTS_W - 1 - lengths[i], pub_seed, addr,
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hash_state_seeded);
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}
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}
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