1009 rivejä
31 KiB
C
1009 rivejä
31 KiB
C
/*
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xmss_fast.c version 20160722
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Andreas Hülsing
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Joost Rijneveld
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Public domain.
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*/
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#include "xmss_fast.h"
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#include <stdlib.h>
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#include <string.h>
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#include <stdint.h>
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#include <math.h>
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#include "randombytes.h"
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#include "wots.h"
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#include "hash.h"
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#include "xmss_commons.h"
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#include "hash_address.h"
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#include "params.h"
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/**
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* Used for pseudorandom keygeneration,
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* generates the seed for the WOTS keypair at address addr
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*
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* takes n byte sk_seed and returns n byte seed using 32 byte address addr.
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*/
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static void get_seed(unsigned char *seed, const unsigned char *sk_seed, int n, uint32_t addr[8])
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{
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unsigned char bytes[32];
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// Make sure that chain addr, hash addr, and key bit are 0!
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setChainADRS(addr,0);
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setHashADRS(addr,0);
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setKeyAndMask(addr,0);
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// Generate pseudorandom value
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addr_to_byte(bytes, addr);
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prf(seed, bytes, sk_seed, n);
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}
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/**
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* Initialize BDS state struct
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* parameter names are the same as used in the description of the BDS traversal
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*/
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void xmss_set_bds_state(bds_state *state, unsigned char *stack, int stackoffset, unsigned char *stacklevels, unsigned char *auth, unsigned char *keep, treehash_inst *treehash, unsigned char *retain, int next_leaf)
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{
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state->stack = stack;
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state->stackoffset = stackoffset;
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state->stacklevels = stacklevels;
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state->auth = auth;
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state->keep = keep;
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state->treehash = treehash;
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state->retain = retain;
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state->next_leaf = next_leaf;
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}
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/**
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* Computes a leaf from a WOTS public key using an L-tree.
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*/
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static void l_tree(unsigned char *leaf, unsigned char *wots_pk, const unsigned char *pub_seed, uint32_t addr[8])
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{
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unsigned int l = XMSS_WOTS_LEN;
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unsigned int n = XMSS_N;
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uint32_t i = 0;
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uint32_t height = 0;
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uint32_t bound;
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//ADRS.setTreeHeight(0);
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setTreeHeight(addr, height);
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while (l > 1) {
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bound = l >> 1; //floor(l / 2);
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for (i = 0; i < bound; i++) {
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//ADRS.setTreeIndex(i);
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setTreeIndex(addr, i);
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//wots_pk[i] = RAND_HASH(pk[2i], pk[2i + 1], SEED, ADRS);
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hash_h(wots_pk+i*n, wots_pk+i*2*n, pub_seed, addr, n);
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}
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//if ( l % 2 == 1 ) {
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if (l & 1) {
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//pk[floor(l / 2) + 1] = pk[l];
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memcpy(wots_pk+(l>>1)*n, wots_pk+(l-1)*n, n);
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//l = ceil(l / 2);
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l=(l>>1)+1;
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}
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else {
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//l = ceil(l / 2);
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l=(l>>1);
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}
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//ADRS.setTreeHeight(ADRS.getTreeHeight() + 1);
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height++;
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setTreeHeight(addr, height);
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}
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//return pk[0];
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memcpy(leaf, wots_pk, n);
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}
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/**
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* Computes the leaf at a given address. First generates the WOTS key pair, then computes leaf using l_tree. As this happens position independent, we only require that addr encodes the right ltree-address.
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*/
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static void gen_leaf_wots(unsigned char *leaf, const unsigned char *sk_seed, const unsigned char *pub_seed, uint32_t ltree_addr[8], uint32_t ots_addr[8])
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{
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unsigned char seed[XMSS_N];
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unsigned char pk[XMSS_WOTS_KEYSIZE];
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get_seed(seed, sk_seed, XMSS_N, ots_addr);
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wots_pkgen(pk, seed, pub_seed, ots_addr);
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l_tree(leaf, pk, pub_seed, ltree_addr);
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}
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static int treehash_minheight_on_stack(bds_state* state, const treehash_inst *treehash) {
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unsigned int r = XMSS_TREEHEIGHT, i;
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for (i = 0; i < treehash->stackusage; i++) {
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if (state->stacklevels[state->stackoffset - i - 1] < r) {
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r = state->stacklevels[state->stackoffset - i - 1];
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}
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}
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return r;
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}
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/**
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* Merkle's TreeHash algorithm. The address only needs to initialize the first 78 bits of addr. Everything else will be set by treehash.
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* Currently only used for key generation.
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*
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*/
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static void treehash_setup(unsigned char *node, int height, int index, bds_state *state, const unsigned char *sk_seed, const unsigned char *pub_seed, const uint32_t addr[8])
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{
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unsigned int idx = index;
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// use three different addresses because at this point we use all three formats in parallel
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uint32_t ots_addr[8];
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uint32_t ltree_addr[8];
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uint32_t node_addr[8];
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// only copy layer and tree address parts
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memcpy(ots_addr, addr, 12);
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// type = ots
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setType(ots_addr, 0);
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memcpy(ltree_addr, addr, 12);
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setType(ltree_addr, 1);
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memcpy(node_addr, addr, 12);
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setType(node_addr, 2);
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uint32_t lastnode, i;
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unsigned char stack[(height+1)*XMSS_N];
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unsigned int stacklevels[height+1];
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unsigned int stackoffset=0;
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unsigned int nodeh;
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lastnode = idx+(1<<height);
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for (i = 0; i < XMSS_TREEHEIGHT-XMSS_BDS_K; i++) {
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state->treehash[i].h = i;
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state->treehash[i].completed = 1;
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state->treehash[i].stackusage = 0;
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}
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i = 0;
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for (; idx < lastnode; idx++) {
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setLtreeADRS(ltree_addr, idx);
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setOTSADRS(ots_addr, idx);
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gen_leaf_wots(stack+stackoffset*XMSS_N, sk_seed, pub_seed, ltree_addr, ots_addr);
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stacklevels[stackoffset] = 0;
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stackoffset++;
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if (XMSS_TREEHEIGHT - XMSS_BDS_K > 0 && i == 3) {
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memcpy(state->treehash[0].node, stack+stackoffset*XMSS_N, XMSS_N);
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}
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while (stackoffset>1 && stacklevels[stackoffset-1] == stacklevels[stackoffset-2])
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{
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nodeh = stacklevels[stackoffset-1];
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if (i >> nodeh == 1) {
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memcpy(state->auth + nodeh*XMSS_N, stack+(stackoffset-1)*XMSS_N, XMSS_N);
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}
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else {
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if (nodeh < XMSS_TREEHEIGHT - XMSS_BDS_K && i >> nodeh == 3) {
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memcpy(state->treehash[nodeh].node, stack+(stackoffset-1)*XMSS_N, XMSS_N);
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}
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else if (nodeh >= XMSS_TREEHEIGHT - XMSS_BDS_K) {
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memcpy(state->retain + ((1 << (XMSS_TREEHEIGHT - 1 - nodeh)) + nodeh - XMSS_TREEHEIGHT + (((i >> nodeh) - 3) >> 1)) * XMSS_N, stack+(stackoffset-1)*XMSS_N, XMSS_N);
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}
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}
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setTreeHeight(node_addr, stacklevels[stackoffset-1]);
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setTreeIndex(node_addr, (idx >> (stacklevels[stackoffset-1]+1)));
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hash_h(stack+(stackoffset-2)*XMSS_N, stack+(stackoffset-2)*XMSS_N, pub_seed,
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node_addr, XMSS_N);
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stacklevels[stackoffset-2]++;
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stackoffset--;
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}
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i++;
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}
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for (i = 0; i < XMSS_N; i++)
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node[i] = stack[i];
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}
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static void treehash_update(treehash_inst *treehash, bds_state *state, const unsigned char *sk_seed, const unsigned char *pub_seed, const uint32_t addr[8]) {
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uint32_t ots_addr[8];
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uint32_t ltree_addr[8];
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uint32_t node_addr[8];
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// only copy layer and tree address parts
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memcpy(ots_addr, addr, 12);
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// type = ots
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setType(ots_addr, 0);
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memcpy(ltree_addr, addr, 12);
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setType(ltree_addr, 1);
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memcpy(node_addr, addr, 12);
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setType(node_addr, 2);
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setLtreeADRS(ltree_addr, treehash->next_idx);
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setOTSADRS(ots_addr, treehash->next_idx);
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unsigned char nodebuffer[2 * XMSS_N];
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unsigned int nodeheight = 0;
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gen_leaf_wots(nodebuffer, sk_seed, pub_seed, ltree_addr, ots_addr);
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while (treehash->stackusage > 0 && state->stacklevels[state->stackoffset-1] == nodeheight) {
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memcpy(nodebuffer + XMSS_N, nodebuffer, XMSS_N);
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memcpy(nodebuffer, state->stack + (state->stackoffset-1)*XMSS_N, XMSS_N);
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setTreeHeight(node_addr, nodeheight);
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setTreeIndex(node_addr, (treehash->next_idx >> (nodeheight+1)));
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hash_h(nodebuffer, nodebuffer, pub_seed, node_addr, XMSS_N);
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nodeheight++;
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treehash->stackusage--;
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state->stackoffset--;
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}
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if (nodeheight == treehash->h) { // this also implies stackusage == 0
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memcpy(treehash->node, nodebuffer, XMSS_N);
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treehash->completed = 1;
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}
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else {
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memcpy(state->stack + state->stackoffset*XMSS_N, nodebuffer, XMSS_N);
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treehash->stackusage++;
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state->stacklevels[state->stackoffset] = nodeheight;
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state->stackoffset++;
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treehash->next_idx++;
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}
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}
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/**
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* Computes a root node given a leaf and an authapth
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*/
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static void validate_authpath(unsigned char *root, const unsigned char *leaf, unsigned long leafidx, const unsigned char *authpath, const unsigned char *pub_seed, uint32_t addr[8])
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{
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uint32_t i, j;
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unsigned char buffer[2*XMSS_N];
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// If leafidx is odd (last bit = 1), current path element is a right child and authpath has to go to the left.
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// Otherwise, it is the other way around
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if (leafidx & 1) {
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for (j = 0; j < XMSS_N; j++)
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buffer[XMSS_N+j] = leaf[j];
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for (j = 0; j < XMSS_N; j++)
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buffer[j] = authpath[j];
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}
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else {
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for (j = 0; j < XMSS_N; j++)
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buffer[j] = leaf[j];
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for (j = 0; j < XMSS_N; j++)
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buffer[XMSS_N+j] = authpath[j];
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}
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authpath += XMSS_N;
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for (i=0; i < XMSS_TREEHEIGHT-1; i++) {
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setTreeHeight(addr, i);
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leafidx >>= 1;
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setTreeIndex(addr, leafidx);
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if (leafidx&1) {
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hash_h(buffer+XMSS_N, buffer, pub_seed, addr, XMSS_N);
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for (j = 0; j < XMSS_N; j++)
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buffer[j] = authpath[j];
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}
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else {
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hash_h(buffer, buffer, pub_seed, addr, XMSS_N);
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for (j = 0; j < XMSS_N; j++)
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buffer[j+XMSS_N] = authpath[j];
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}
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authpath += XMSS_N;
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}
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setTreeHeight(addr, (XMSS_TREEHEIGHT-1));
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leafidx >>= 1;
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setTreeIndex(addr, leafidx);
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hash_h(root, buffer, pub_seed, addr, XMSS_N);
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}
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/**
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* Performs one treehash update on the instance that needs it the most.
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* Returns 1 if such an instance was not found
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**/
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static char bds_treehash_update(bds_state *state, unsigned int updates, const unsigned char *sk_seed, unsigned char *pub_seed, const uint32_t addr[8]) {
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uint32_t i, j;
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unsigned int level, l_min, low;
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unsigned int used = 0;
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for (j = 0; j < updates; j++) {
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l_min = XMSS_TREEHEIGHT;
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level = XMSS_TREEHEIGHT - XMSS_BDS_K;
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for (i = 0; i < XMSS_TREEHEIGHT - XMSS_BDS_K; i++) {
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if (state->treehash[i].completed) {
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low = XMSS_TREEHEIGHT;
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}
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else if (state->treehash[i].stackusage == 0) {
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low = i;
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}
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else {
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low = treehash_minheight_on_stack(state, &(state->treehash[i]));
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}
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if (low < l_min) {
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level = i;
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l_min = low;
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}
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}
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if (level == XMSS_TREEHEIGHT - XMSS_BDS_K) {
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break;
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}
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treehash_update(&(state->treehash[level]), state, sk_seed, pub_seed, addr);
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used++;
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}
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return updates - used;
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}
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/**
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* Updates the state (typically NEXT_i) by adding a leaf and updating the stack
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* Returns 1 if all leaf nodes have already been processed
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**/
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static char bds_state_update(bds_state *state, const unsigned char *sk_seed, unsigned char *pub_seed, const uint32_t addr[8]) {
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uint32_t ltree_addr[8];
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uint32_t node_addr[8];
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uint32_t ots_addr[8];
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int nodeh;
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int idx = state->next_leaf;
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if (idx == 1 << XMSS_TREEHEIGHT) {
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return 1;
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}
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// only copy layer and tree address parts
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memcpy(ots_addr, addr, 12);
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// type = ots
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setType(ots_addr, 0);
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memcpy(ltree_addr, addr, 12);
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setType(ltree_addr, 1);
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memcpy(node_addr, addr, 12);
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setType(node_addr, 2);
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setOTSADRS(ots_addr, idx);
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setLtreeADRS(ltree_addr, idx);
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gen_leaf_wots(state->stack+state->stackoffset*XMSS_N, sk_seed, pub_seed, ltree_addr, ots_addr);
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state->stacklevels[state->stackoffset] = 0;
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state->stackoffset++;
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if (XMSS_TREEHEIGHT - XMSS_BDS_K > 0 && idx == 3) {
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memcpy(state->treehash[0].node, state->stack+state->stackoffset*XMSS_N, XMSS_N);
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}
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while (state->stackoffset>1 && state->stacklevels[state->stackoffset-1] == state->stacklevels[state->stackoffset-2]) {
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nodeh = state->stacklevels[state->stackoffset-1];
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if (idx >> nodeh == 1) {
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memcpy(state->auth + nodeh*XMSS_N, state->stack+(state->stackoffset-1)*XMSS_N, XMSS_N);
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}
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else {
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if (nodeh < XMSS_TREEHEIGHT - XMSS_BDS_K && idx >> nodeh == 3) {
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memcpy(state->treehash[nodeh].node, state->stack+(state->stackoffset-1)*XMSS_N, XMSS_N);
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}
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else if (nodeh >= XMSS_TREEHEIGHT - XMSS_BDS_K) {
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memcpy(state->retain + ((1 << (XMSS_TREEHEIGHT - 1 - nodeh)) + nodeh - XMSS_TREEHEIGHT + (((idx >> nodeh) - 3) >> 1)) * XMSS_N, state->stack+(state->stackoffset-1)*XMSS_N, XMSS_N);
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}
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}
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setTreeHeight(node_addr, state->stacklevels[state->stackoffset-1]);
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setTreeIndex(node_addr, (idx >> (state->stacklevels[state->stackoffset-1]+1)));
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hash_h(state->stack+(state->stackoffset-2)*XMSS_N, state->stack+(state->stackoffset-2)*XMSS_N, pub_seed, node_addr, XMSS_N);
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state->stacklevels[state->stackoffset-2]++;
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state->stackoffset--;
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}
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state->next_leaf++;
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return 0;
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}
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/**
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* Returns the auth path for node leaf_idx and computes the auth path for the
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* next leaf node, using the algorithm described by Buchmann, Dahmen and Szydlo
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* in "Post Quantum Cryptography", Springer 2009.
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*/
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static void bds_round(bds_state *state, const unsigned long leaf_idx, const unsigned char *sk_seed, unsigned char *pub_seed, uint32_t addr[8])
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{
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unsigned int i;
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unsigned int tau = XMSS_TREEHEIGHT;
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unsigned int startidx;
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unsigned int offset, rowidx;
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unsigned char buf[2 * XMSS_N];
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uint32_t ots_addr[8];
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uint32_t ltree_addr[8];
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uint32_t node_addr[8];
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// only copy layer and tree address parts
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memcpy(ots_addr, addr, 12);
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// type = ots
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setType(ots_addr, 0);
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memcpy(ltree_addr, addr, 12);
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setType(ltree_addr, 1);
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memcpy(node_addr, addr, 12);
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setType(node_addr, 2);
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for (i = 0; i < XMSS_TREEHEIGHT; i++) {
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if (! ((leaf_idx >> i) & 1)) {
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tau = i;
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break;
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}
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}
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if (tau > 0) {
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memcpy(buf, state->auth + (tau-1) * XMSS_N, XMSS_N);
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// we need to do this before refreshing state->keep to prevent overwriting
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memcpy(buf + XMSS_N, state->keep + ((tau-1) >> 1) * XMSS_N, XMSS_N);
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}
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if (!((leaf_idx >> (tau + 1)) & 1) && (tau < XMSS_TREEHEIGHT - 1)) {
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memcpy(state->keep + (tau >> 1)*XMSS_N, state->auth + tau*XMSS_N, XMSS_N);
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}
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if (tau == 0) {
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setLtreeADRS(ltree_addr, leaf_idx);
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setOTSADRS(ots_addr, leaf_idx);
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gen_leaf_wots(state->auth, sk_seed, pub_seed, ltree_addr, ots_addr);
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}
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else {
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setTreeHeight(node_addr, (tau-1));
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setTreeIndex(node_addr, leaf_idx >> tau);
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hash_h(state->auth + tau * XMSS_N, buf, pub_seed, node_addr, XMSS_N);
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for (i = 0; i < tau; i++) {
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if (i < XMSS_TREEHEIGHT - XMSS_BDS_K) {
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memcpy(state->auth + i * XMSS_N, state->treehash[i].node, XMSS_N);
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}
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else {
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offset = (1 << (XMSS_TREEHEIGHT - 1 - i)) + i - XMSS_TREEHEIGHT;
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rowidx = ((leaf_idx >> i) - 1) >> 1;
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memcpy(state->auth + i * XMSS_N, state->retain + (offset + rowidx) * XMSS_N, XMSS_N);
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}
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}
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|
|
for (i = 0; i < ((tau < XMSS_TREEHEIGHT - XMSS_BDS_K) ? tau : (XMSS_TREEHEIGHT - XMSS_BDS_K)); i++) {
|
|
startidx = leaf_idx + 1 + 3 * (1 << i);
|
|
if (startidx < 1U << XMSS_TREEHEIGHT) {
|
|
state->treehash[i].h = i;
|
|
state->treehash[i].next_idx = startidx;
|
|
state->treehash[i].completed = 0;
|
|
state->treehash[i].stackusage = 0;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Generates a XMSS key pair for a given parameter set.
|
|
* Format sk: [(32bit) idx || SK_SEED || SK_PRF || PUB_SEED || root]
|
|
* Format pk: [root || PUB_SEED] omitting algo oid.
|
|
*/
|
|
int xmss_keypair(unsigned char *pk, unsigned char *sk, bds_state *state)
|
|
{
|
|
// Set idx = 0
|
|
sk[0] = 0;
|
|
sk[1] = 0;
|
|
sk[2] = 0;
|
|
sk[3] = 0;
|
|
// Init SK_SEED (n byte), SK_PRF (n byte), and PUB_SEED (n byte)
|
|
randombytes(sk+4, 3*XMSS_N);
|
|
// Copy PUB_SEED to public key
|
|
memcpy(pk+XMSS_N, sk+4+2*XMSS_N, XMSS_N);
|
|
|
|
uint32_t addr[8] = {0, 0, 0, 0, 0, 0, 0, 0};
|
|
|
|
// Compute root
|
|
treehash_setup(pk, XMSS_TREEHEIGHT, 0, state, sk+4, sk+4+2*XMSS_N, addr);
|
|
// copy root to sk
|
|
memcpy(sk+4+3*XMSS_N, pk, XMSS_N);
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* Signs a message.
|
|
* Returns
|
|
* 1. an array containing the signature followed by the message AND
|
|
* 2. an updated secret key!
|
|
*
|
|
*/
|
|
int xmss_sign(unsigned char *sk, bds_state *state, unsigned char *sig_msg, unsigned long long *sig_msg_len, const unsigned char *msg, unsigned long long msglen)
|
|
{
|
|
uint16_t i = 0;
|
|
|
|
// Extract SK
|
|
unsigned long idx = ((unsigned long)sk[0] << 24) | ((unsigned long)sk[1] << 16) | ((unsigned long)sk[2] << 8) | sk[3];
|
|
unsigned char sk_seed[XMSS_N];
|
|
memcpy(sk_seed, sk+4, XMSS_N);
|
|
unsigned char sk_prf[XMSS_N];
|
|
memcpy(sk_prf, sk+4+XMSS_N, XMSS_N);
|
|
unsigned char pub_seed[XMSS_N];
|
|
memcpy(pub_seed, sk+4+2*XMSS_N, XMSS_N);
|
|
|
|
// index as 32 bytes string
|
|
unsigned char idx_bytes_32[32];
|
|
to_byte(idx_bytes_32, idx, 32);
|
|
|
|
unsigned char hash_key[3*XMSS_N];
|
|
|
|
// Update SK
|
|
sk[0] = ((idx + 1) >> 24) & 255;
|
|
sk[1] = ((idx + 1) >> 16) & 255;
|
|
sk[2] = ((idx + 1) >> 8) & 255;
|
|
sk[3] = (idx + 1) & 255;
|
|
// -- Secret key for this non-forward-secure version is now updated.
|
|
// -- A productive implementation should use a file handle instead and write the updated secret key at this point!
|
|
|
|
// Init working params
|
|
unsigned char R[XMSS_N];
|
|
unsigned char msg_h[XMSS_N];
|
|
unsigned char ots_seed[XMSS_N];
|
|
uint32_t ots_addr[8] = {0, 0, 0, 0, 0, 0, 0, 0};
|
|
|
|
// ---------------------------------
|
|
// Message Hashing
|
|
// ---------------------------------
|
|
|
|
// Message Hash:
|
|
// First compute pseudorandom value
|
|
prf(R, idx_bytes_32, sk_prf, XMSS_N);
|
|
// Generate hash key (R || root || idx)
|
|
memcpy(hash_key, R, XMSS_N);
|
|
memcpy(hash_key+XMSS_N, sk+4+3*XMSS_N, XMSS_N);
|
|
to_byte(hash_key+2*XMSS_N, idx, XMSS_N);
|
|
// Then use it for message digest
|
|
h_msg(msg_h, msg, msglen, hash_key, 3*XMSS_N, XMSS_N);
|
|
|
|
// Start collecting signature
|
|
*sig_msg_len = 0;
|
|
|
|
// Copy index to signature
|
|
sig_msg[0] = (idx >> 24) & 255;
|
|
sig_msg[1] = (idx >> 16) & 255;
|
|
sig_msg[2] = (idx >> 8) & 255;
|
|
sig_msg[3] = idx & 255;
|
|
|
|
sig_msg += 4;
|
|
*sig_msg_len += 4;
|
|
|
|
// Copy R to signature
|
|
for (i = 0; i < XMSS_N; i++)
|
|
sig_msg[i] = R[i];
|
|
|
|
sig_msg += XMSS_N;
|
|
*sig_msg_len += XMSS_N;
|
|
|
|
// ----------------------------------
|
|
// Now we start to "really sign"
|
|
// ----------------------------------
|
|
|
|
// Prepare Address
|
|
setType(ots_addr, 0);
|
|
setOTSADRS(ots_addr, idx);
|
|
|
|
// Compute seed for OTS key pair
|
|
get_seed(ots_seed, sk_seed, XMSS_N, ots_addr);
|
|
|
|
// Compute WOTS signature
|
|
wots_sign(sig_msg, msg_h, ots_seed, pub_seed, ots_addr);
|
|
|
|
sig_msg += XMSS_WOTS_KEYSIZE;
|
|
*sig_msg_len += XMSS_WOTS_KEYSIZE;
|
|
|
|
// the auth path was already computed during the previous round
|
|
memcpy(sig_msg, state->auth, XMSS_TREEHEIGHT*XMSS_N);
|
|
|
|
if (idx < (1U << XMSS_TREEHEIGHT) - 1) {
|
|
bds_round(state, idx, sk_seed, pub_seed, ots_addr);
|
|
bds_treehash_update(state, (XMSS_TREEHEIGHT - XMSS_BDS_K) >> 1, sk_seed, pub_seed, ots_addr);
|
|
}
|
|
|
|
sig_msg += XMSS_TREEHEIGHT*XMSS_N;
|
|
*sig_msg_len += XMSS_TREEHEIGHT*XMSS_N;
|
|
|
|
memcpy(sig_msg, msg, msglen);
|
|
*sig_msg_len += msglen;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* Verifies a given message signature pair under a given public key.
|
|
*/
|
|
int xmss_sign_open(unsigned char *msg, unsigned long long *msglen, const unsigned char *sig_msg, unsigned long long sig_msg_len, const unsigned char *pk)
|
|
{
|
|
unsigned long long i, m_len;
|
|
unsigned long idx=0;
|
|
unsigned char wots_pk[XMSS_WOTS_KEYSIZE];
|
|
unsigned char pkhash[XMSS_N];
|
|
unsigned char root[XMSS_N];
|
|
unsigned char msg_h[XMSS_N];
|
|
unsigned char hash_key[3*XMSS_N];
|
|
|
|
unsigned char pub_seed[XMSS_N];
|
|
memcpy(pub_seed, pk+XMSS_N, XMSS_N);
|
|
|
|
// Init addresses
|
|
uint32_t ots_addr[8] = {0, 0, 0, 0, 0, 0, 0, 0};
|
|
uint32_t ltree_addr[8] = {0, 0, 0, 0, 0, 0, 0, 0};
|
|
uint32_t node_addr[8] = {0, 0, 0, 0, 0, 0, 0, 0};
|
|
|
|
setType(ots_addr, 0);
|
|
setType(ltree_addr, 1);
|
|
setType(node_addr, 2);
|
|
|
|
// Extract index
|
|
idx = ((unsigned long)sig_msg[0] << 24) | ((unsigned long)sig_msg[1] << 16) | ((unsigned long)sig_msg[2] << 8) | sig_msg[3];
|
|
|
|
// Generate hash key (R || root || idx)
|
|
memcpy(hash_key, sig_msg+4,XMSS_N);
|
|
memcpy(hash_key+XMSS_N, pk, XMSS_N);
|
|
to_byte(hash_key+2*XMSS_N, idx, XMSS_N);
|
|
|
|
sig_msg += (XMSS_N+4);
|
|
sig_msg_len -= (XMSS_N+4);
|
|
|
|
// hash message
|
|
unsigned long long tmp_sig_len = XMSS_WOTS_KEYSIZE+XMSS_TREEHEIGHT*XMSS_N;
|
|
m_len = sig_msg_len - tmp_sig_len;
|
|
h_msg(msg_h, sig_msg + tmp_sig_len, m_len, hash_key, 3*XMSS_N, XMSS_N);
|
|
|
|
//-----------------------
|
|
// Verify signature
|
|
//-----------------------
|
|
|
|
// Prepare Address
|
|
setOTSADRS(ots_addr, idx);
|
|
// Check WOTS signature
|
|
wots_pkFromSig(wots_pk, sig_msg, msg_h, pub_seed, ots_addr);
|
|
|
|
sig_msg += XMSS_WOTS_KEYSIZE;
|
|
sig_msg_len -= XMSS_WOTS_KEYSIZE;
|
|
|
|
// Compute Ltree
|
|
setLtreeADRS(ltree_addr, idx);
|
|
l_tree(pkhash, wots_pk, pub_seed, ltree_addr);
|
|
|
|
// Compute root
|
|
validate_authpath(root, pkhash, idx, sig_msg, pub_seed, node_addr);
|
|
|
|
sig_msg += XMSS_TREEHEIGHT*XMSS_N;
|
|
sig_msg_len -= XMSS_TREEHEIGHT*XMSS_N;
|
|
|
|
for (i = 0; i < XMSS_N; i++)
|
|
if (root[i] != pk[i])
|
|
goto fail;
|
|
|
|
*msglen = sig_msg_len;
|
|
for (i = 0; i < *msglen; i++)
|
|
msg[i] = sig_msg[i];
|
|
|
|
return 0;
|
|
|
|
|
|
fail:
|
|
*msglen = sig_msg_len;
|
|
for (i = 0; i < *msglen; i++)
|
|
msg[i] = 0;
|
|
*msglen = -1;
|
|
return -1;
|
|
}
|
|
|
|
/*
|
|
* Generates a XMSSMT key pair for a given parameter set.
|
|
* Format sk: [(ceil(h/8) bit) idx || SK_SEED || SK_PRF || PUB_SEED || root]
|
|
* Format pk: [root || PUB_SEED] omitting algo oid.
|
|
*/
|
|
int xmssmt_keypair(unsigned char *pk, unsigned char *sk, bds_state *states, unsigned char *wots_sigs)
|
|
{
|
|
unsigned char ots_seed[XMSS_N];
|
|
int i;
|
|
// Set idx = 0
|
|
for (i = 0; i < XMSS_INDEX_LEN; i++) {
|
|
sk[i] = 0;
|
|
}
|
|
// Init SK_SEED (XMSS_N byte), SK_PRF (XMSS_N byte), and PUB_SEED (XMSS_N byte)
|
|
randombytes(sk+XMSS_INDEX_LEN, 3*XMSS_N);
|
|
// Copy PUB_SEED to public key
|
|
memcpy(pk+XMSS_N, sk+XMSS_INDEX_LEN+2*XMSS_N, XMSS_N);
|
|
|
|
uint32_t addr[8] = {0, 0, 0, 0, 0, 0, 0, 0};
|
|
// Start with the bottom-most layer
|
|
setLayerADRS(addr, 0);
|
|
// Set up state and compute wots signatures for all but topmost tree root
|
|
for (i = 0; i < XMSS_D - 1; i++) {
|
|
// Compute seed for OTS key pair
|
|
treehash_setup(pk, XMSS_TREEHEIGHT, 0, states + i, sk+XMSS_INDEX_LEN, pk+XMSS_N, addr);
|
|
setLayerADRS(addr, (i+1));
|
|
get_seed(ots_seed, sk+XMSS_INDEX_LEN, XMSS_N, addr);
|
|
wots_sign(wots_sigs + i*XMSS_WOTS_KEYSIZE, pk, ots_seed, pk+XMSS_N, addr);
|
|
}
|
|
// Address now points to the single tree on layer d-1
|
|
treehash_setup(pk, XMSS_TREEHEIGHT, 0, states + i, sk+XMSS_INDEX_LEN, pk+XMSS_N, addr);
|
|
memcpy(sk+XMSS_INDEX_LEN+3*XMSS_N, pk, XMSS_N);
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* Signs a message.
|
|
* Returns
|
|
* 1. an array containing the signature followed by the message AND
|
|
* 2. an updated secret key!
|
|
*
|
|
*/
|
|
int xmssmt_sign(unsigned char *sk, bds_state *states, unsigned char *wots_sigs, unsigned char *sig_msg, unsigned long long *sig_msg_len, const unsigned char *msg, unsigned long long msglen)
|
|
{
|
|
uint64_t idx_tree;
|
|
uint32_t idx_leaf;
|
|
uint64_t i, j;
|
|
int needswap_upto = -1;
|
|
unsigned int updates;
|
|
|
|
unsigned char sk_seed[XMSS_N];
|
|
unsigned char sk_prf[XMSS_N];
|
|
unsigned char pub_seed[XMSS_N];
|
|
// Init working params
|
|
unsigned char R[XMSS_N];
|
|
unsigned char msg_h[XMSS_N];
|
|
unsigned char hash_key[3*XMSS_N];
|
|
unsigned char ots_seed[XMSS_N];
|
|
uint32_t addr[8] = {0, 0, 0, 0, 0, 0, 0, 0};
|
|
uint32_t ots_addr[8] = {0, 0, 0, 0, 0, 0, 0, 0};
|
|
unsigned char idx_bytes_32[32];
|
|
bds_state tmp;
|
|
|
|
// Extract SK
|
|
unsigned long long idx = 0;
|
|
for (i = 0; i < XMSS_INDEX_LEN; i++) {
|
|
idx |= ((unsigned long long)sk[i]) << 8*(XMSS_INDEX_LEN - 1 - i);
|
|
}
|
|
|
|
memcpy(sk_seed, sk+XMSS_INDEX_LEN, XMSS_N);
|
|
memcpy(sk_prf, sk+XMSS_INDEX_LEN+XMSS_N, XMSS_N);
|
|
memcpy(pub_seed, sk+XMSS_INDEX_LEN+2*XMSS_N, XMSS_N);
|
|
|
|
// Update SK
|
|
for (i = 0; i < XMSS_INDEX_LEN; i++) {
|
|
sk[i] = ((idx + 1) >> 8*(XMSS_INDEX_LEN - 1 - i)) & 255;
|
|
}
|
|
// -- Secret key for this non-forward-secure version is now updated.
|
|
// -- A productive implementation should use a file handle instead and write the updated secret key at this point!
|
|
|
|
|
|
// ---------------------------------
|
|
// Message Hashing
|
|
// ---------------------------------
|
|
|
|
// Message Hash:
|
|
// First compute pseudorandom value
|
|
to_byte(idx_bytes_32, idx, 32);
|
|
prf(R, idx_bytes_32, sk_prf, XMSS_N);
|
|
// Generate hash key (R || root || idx)
|
|
memcpy(hash_key, R, XMSS_N);
|
|
memcpy(hash_key+XMSS_N, sk+XMSS_INDEX_LEN+3*XMSS_N, XMSS_N);
|
|
to_byte(hash_key+2*XMSS_N, idx, XMSS_N);
|
|
|
|
// Then use it for message digest
|
|
h_msg(msg_h, msg, msglen, hash_key, 3*XMSS_N, XMSS_N);
|
|
|
|
// Start collecting signature
|
|
*sig_msg_len = 0;
|
|
|
|
// Copy index to signature
|
|
for (i = 0; i < XMSS_INDEX_LEN; i++) {
|
|
sig_msg[i] = (idx >> 8*(XMSS_INDEX_LEN - 1 - i)) & 255;
|
|
}
|
|
|
|
sig_msg += XMSS_INDEX_LEN;
|
|
*sig_msg_len += XMSS_INDEX_LEN;
|
|
|
|
// Copy R to signature
|
|
for (i = 0; i < XMSS_N; i++)
|
|
sig_msg[i] = R[i];
|
|
|
|
sig_msg += XMSS_N;
|
|
*sig_msg_len += XMSS_N;
|
|
|
|
// ----------------------------------
|
|
// Now we start to "really sign"
|
|
// ----------------------------------
|
|
|
|
// Handle lowest layer separately as it is slightly different...
|
|
|
|
// Prepare Address
|
|
setType(ots_addr, 0);
|
|
idx_tree = idx >> XMSS_TREEHEIGHT;
|
|
idx_leaf = (idx & ((1 << XMSS_TREEHEIGHT)-1));
|
|
setLayerADRS(ots_addr, 0);
|
|
setTreeADRS(ots_addr, idx_tree);
|
|
setOTSADRS(ots_addr, idx_leaf);
|
|
|
|
// Compute seed for OTS key pair
|
|
get_seed(ots_seed, sk_seed, XMSS_N, ots_addr);
|
|
|
|
// Compute WOTS signature
|
|
wots_sign(sig_msg, msg_h, ots_seed, pub_seed, ots_addr);
|
|
|
|
sig_msg += XMSS_WOTS_KEYSIZE;
|
|
*sig_msg_len += XMSS_WOTS_KEYSIZE;
|
|
|
|
memcpy(sig_msg, states[0].auth, XMSS_TREEHEIGHT*XMSS_N);
|
|
sig_msg += XMSS_TREEHEIGHT*XMSS_N;
|
|
*sig_msg_len += XMSS_TREEHEIGHT*XMSS_N;
|
|
|
|
// prepare signature of remaining layers
|
|
for (i = 1; i < XMSS_D; i++) {
|
|
// put WOTS signature in place
|
|
memcpy(sig_msg, wots_sigs + (i-1)*XMSS_WOTS_KEYSIZE, XMSS_WOTS_KEYSIZE);
|
|
|
|
sig_msg += XMSS_WOTS_KEYSIZE;
|
|
*sig_msg_len += XMSS_WOTS_KEYSIZE;
|
|
|
|
// put AUTH nodes in place
|
|
memcpy(sig_msg, states[i].auth, XMSS_TREEHEIGHT*XMSS_N);
|
|
sig_msg += XMSS_TREEHEIGHT*XMSS_N;
|
|
*sig_msg_len += XMSS_TREEHEIGHT*XMSS_N;
|
|
}
|
|
|
|
updates = (XMSS_TREEHEIGHT - XMSS_BDS_K) >> 1;
|
|
|
|
setTreeADRS(addr, (idx_tree + 1));
|
|
// mandatory update for NEXT_0 (does not count towards h-k/2) if NEXT_0 exists
|
|
if ((1 + idx_tree) * (1 << XMSS_TREEHEIGHT) + idx_leaf < (1ULL << XMSS_FULLHEIGHT)) {
|
|
bds_state_update(&states[XMSS_D], sk_seed, pub_seed, addr);
|
|
}
|
|
|
|
for (i = 0; i < XMSS_D; i++) {
|
|
// check if we're not at the end of a tree
|
|
if (! (((idx + 1) & ((1ULL << ((i+1)*XMSS_TREEHEIGHT)) - 1)) == 0)) {
|
|
idx_leaf = (idx >> (XMSS_TREEHEIGHT * i)) & ((1 << XMSS_TREEHEIGHT)-1);
|
|
idx_tree = (idx >> (XMSS_TREEHEIGHT * (i+1)));
|
|
setLayerADRS(addr, i);
|
|
setTreeADRS(addr, idx_tree);
|
|
if (i == (unsigned int) (needswap_upto + 1)) {
|
|
bds_round(&states[i], idx_leaf, sk_seed, pub_seed, addr);
|
|
}
|
|
updates = bds_treehash_update(&states[i], updates, sk_seed, pub_seed, addr);
|
|
setTreeADRS(addr, (idx_tree + 1));
|
|
// if a NEXT-tree exists for this level;
|
|
if ((1 + idx_tree) * (1 << XMSS_TREEHEIGHT) + idx_leaf < (1ULL << (XMSS_FULLHEIGHT - XMSS_TREEHEIGHT * i))) {
|
|
if (i > 0 && updates > 0 && states[XMSS_D + i].next_leaf < (1ULL << XMSS_FULLHEIGHT)) {
|
|
bds_state_update(&states[XMSS_D + i], sk_seed, pub_seed, addr);
|
|
updates--;
|
|
}
|
|
}
|
|
}
|
|
else if (idx < (1ULL << XMSS_FULLHEIGHT) - 1) {
|
|
memcpy(&tmp, states+XMSS_D + i, sizeof(bds_state));
|
|
memcpy(states+XMSS_D + i, states + i, sizeof(bds_state));
|
|
memcpy(states + i, &tmp, sizeof(bds_state));
|
|
|
|
setLayerADRS(ots_addr, (i+1));
|
|
setTreeADRS(ots_addr, ((idx + 1) >> ((i+2) * XMSS_TREEHEIGHT)));
|
|
setOTSADRS(ots_addr, (((idx >> ((i+1) * XMSS_TREEHEIGHT)) + 1) & ((1 << XMSS_TREEHEIGHT)-1)));
|
|
|
|
get_seed(ots_seed, sk+XMSS_INDEX_LEN, XMSS_N, ots_addr);
|
|
wots_sign(wots_sigs + i*XMSS_WOTS_KEYSIZE, states[i].stack, ots_seed, pub_seed, ots_addr);
|
|
|
|
states[XMSS_D + i].stackoffset = 0;
|
|
states[XMSS_D + i].next_leaf = 0;
|
|
|
|
updates--; // WOTS-signing counts as one update
|
|
needswap_upto = i;
|
|
for (j = 0; j < XMSS_TREEHEIGHT-XMSS_BDS_K; j++) {
|
|
states[i].treehash[j].completed = 1;
|
|
}
|
|
}
|
|
}
|
|
|
|
memcpy(sig_msg, msg, msglen);
|
|
*sig_msg_len += msglen;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* Verifies a given message signature pair under a given public key.
|
|
*/
|
|
int xmssmt_sign_open(unsigned char *msg, unsigned long long *msglen, const unsigned char *sig_msg, unsigned long long sig_msg_len, const unsigned char *pk)
|
|
{
|
|
uint64_t idx_tree;
|
|
uint32_t idx_leaf;
|
|
|
|
unsigned long long i, m_len;
|
|
unsigned long long idx=0;
|
|
unsigned char wots_pk[XMSS_WOTS_KEYSIZE];
|
|
unsigned char pkhash[XMSS_N];
|
|
unsigned char root[XMSS_N];
|
|
unsigned char msg_h[XMSS_N];
|
|
unsigned char hash_key[3*XMSS_N];
|
|
|
|
unsigned char pub_seed[XMSS_N];
|
|
memcpy(pub_seed, pk+XMSS_N, XMSS_N);
|
|
|
|
// Init addresses
|
|
uint32_t ots_addr[8] = {0, 0, 0, 0, 0, 0, 0, 0};
|
|
uint32_t ltree_addr[8] = {0, 0, 0, 0, 0, 0, 0, 0};
|
|
uint32_t node_addr[8] = {0, 0, 0, 0, 0, 0, 0, 0};
|
|
|
|
// Extract index
|
|
for (i = 0; i < XMSS_INDEX_LEN; i++) {
|
|
idx |= ((unsigned long long)sig_msg[i]) << (8*(XMSS_INDEX_LEN - 1 - i));
|
|
}
|
|
sig_msg += XMSS_INDEX_LEN;
|
|
sig_msg_len -= XMSS_INDEX_LEN;
|
|
|
|
// Generate hash key (R || root || idx)
|
|
memcpy(hash_key, sig_msg,XMSS_N);
|
|
memcpy(hash_key+XMSS_N, pk, XMSS_N);
|
|
to_byte(hash_key+2*XMSS_N, idx, XMSS_N);
|
|
|
|
sig_msg += XMSS_N;
|
|
sig_msg_len -= XMSS_N;
|
|
|
|
|
|
// hash message (recall, R is now on pole position at sig_msg
|
|
unsigned long long tmp_sig_len = (XMSS_D * XMSS_WOTS_KEYSIZE) + (XMSS_FULLHEIGHT * XMSS_N);
|
|
m_len = sig_msg_len - tmp_sig_len;
|
|
h_msg(msg_h, sig_msg + tmp_sig_len, m_len, hash_key, 3*XMSS_N, XMSS_N);
|
|
|
|
|
|
//-----------------------
|
|
// Verify signature
|
|
//-----------------------
|
|
|
|
// Prepare Address
|
|
idx_tree = idx >> XMSS_TREEHEIGHT;
|
|
idx_leaf = (idx & ((1 << XMSS_TREEHEIGHT)-1));
|
|
setLayerADRS(ots_addr, 0);
|
|
setTreeADRS(ots_addr, idx_tree);
|
|
setType(ots_addr, 0);
|
|
|
|
memcpy(ltree_addr, ots_addr, 12);
|
|
setType(ltree_addr, 1);
|
|
|
|
memcpy(node_addr, ltree_addr, 12);
|
|
setType(node_addr, 2);
|
|
|
|
setOTSADRS(ots_addr, idx_leaf);
|
|
|
|
// Check WOTS signature
|
|
wots_pkFromSig(wots_pk, sig_msg, msg_h, pub_seed, ots_addr);
|
|
|
|
sig_msg += XMSS_WOTS_KEYSIZE;
|
|
sig_msg_len -= XMSS_WOTS_KEYSIZE;
|
|
|
|
// Compute Ltree
|
|
setLtreeADRS(ltree_addr, idx_leaf);
|
|
l_tree(pkhash, wots_pk, pub_seed, ltree_addr);
|
|
|
|
// Compute root
|
|
validate_authpath(root, pkhash, idx_leaf, sig_msg, pub_seed, node_addr);
|
|
|
|
sig_msg += XMSS_TREEHEIGHT*XMSS_N;
|
|
sig_msg_len -= XMSS_TREEHEIGHT*XMSS_N;
|
|
|
|
for (i = 1; i < XMSS_D; i++) {
|
|
// Prepare Address
|
|
idx_leaf = (idx_tree & ((1 << XMSS_TREEHEIGHT)-1));
|
|
idx_tree = idx_tree >> XMSS_TREEHEIGHT;
|
|
|
|
setLayerADRS(ots_addr, i);
|
|
setTreeADRS(ots_addr, idx_tree);
|
|
setType(ots_addr, 0);
|
|
|
|
memcpy(ltree_addr, ots_addr, 12);
|
|
setType(ltree_addr, 1);
|
|
|
|
memcpy(node_addr, ltree_addr, 12);
|
|
setType(node_addr, 2);
|
|
|
|
setOTSADRS(ots_addr, idx_leaf);
|
|
|
|
// Check WOTS signature
|
|
wots_pkFromSig(wots_pk, sig_msg, root, pub_seed, ots_addr);
|
|
|
|
sig_msg += XMSS_WOTS_KEYSIZE;
|
|
sig_msg_len -= XMSS_WOTS_KEYSIZE;
|
|
|
|
// Compute Ltree
|
|
setLtreeADRS(ltree_addr, idx_leaf);
|
|
l_tree(pkhash, wots_pk, pub_seed, ltree_addr);
|
|
|
|
// Compute root
|
|
validate_authpath(root, pkhash, idx_leaf, sig_msg, pub_seed, node_addr);
|
|
|
|
sig_msg += XMSS_TREEHEIGHT*XMSS_N;
|
|
sig_msg_len -= XMSS_TREEHEIGHT*XMSS_N;
|
|
|
|
}
|
|
|
|
for (i = 0; i < XMSS_N; i++)
|
|
if (root[i] != pk[i])
|
|
goto fail;
|
|
|
|
*msglen = sig_msg_len;
|
|
for (i = 0; i < *msglen; i++)
|
|
msg[i] = sig_msg[i];
|
|
|
|
return 0;
|
|
|
|
|
|
fail:
|
|
*msglen = sig_msg_len;
|
|
for (i = 0; i < *msglen; i++)
|
|
msg[i] = 0;
|
|
*msglen = -1;
|
|
return -1;
|
|
} |