193 lines
7.2 KiB
C
193 lines
7.2 KiB
C
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#include <stddef.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 "params.h"
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#include "thash.h"
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#include "utils.h"
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/**
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* Converts the value of 'in' to 'outlen' bytes in big-endian byte order.
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*/
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void PQCLEAN_SPHINCSSHA256192FROBUST_CLEAN_ull_to_bytes(
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unsigned char *out, size_t outlen, unsigned long long in) {
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/* Iterate over out in decreasing order, for big-endianness. */
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for (size_t i = outlen; i > 0; i--) {
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out[i - 1] = in & 0xff;
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in = in >> 8;
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}
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}
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/**
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* Converts the inlen bytes in 'in' from big-endian byte order to an integer.
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*/
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unsigned long long PQCLEAN_SPHINCSSHA256192FROBUST_CLEAN_bytes_to_ull(
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const unsigned char *in, size_t inlen) {
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unsigned long long retval = 0;
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for (size_t i = 0; i < inlen; i++) {
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retval |= ((unsigned long long)in[i]) << (8 * (inlen - 1 - i));
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}
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return retval;
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}
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/**
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* Computes a root node given a leaf and an auth path.
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* Expects address to be complete other than the tree_height and tree_index.
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*/
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void PQCLEAN_SPHINCSSHA256192FROBUST_CLEAN_compute_root(
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unsigned char *root, const unsigned char *leaf,
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uint32_t leaf_idx, uint32_t idx_offset,
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const unsigned char *auth_path, uint32_t tree_height,
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const unsigned char *pub_seed, uint32_t addr[8]) {
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uint32_t i;
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unsigned char buffer[2 * SPX_N];
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/* If leaf_idx is odd (last bit = 1), current path element is a right child
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and auth_path has to go left. Otherwise it is the other way around. */
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if (leaf_idx & 1) {
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memcpy(buffer + SPX_N, leaf, SPX_N);
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memcpy(buffer, auth_path, SPX_N);
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} else {
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memcpy(buffer, leaf, SPX_N);
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memcpy(buffer + SPX_N, auth_path, SPX_N);
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}
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auth_path += SPX_N;
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for (i = 0; i < tree_height - 1; i++) {
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leaf_idx >>= 1;
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idx_offset >>= 1;
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/* Set the address of the node we're creating. */
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PQCLEAN_SPHINCSSHA256192FROBUST_CLEAN_set_tree_height(addr, i + 1);
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PQCLEAN_SPHINCSSHA256192FROBUST_CLEAN_set_tree_index(
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addr, leaf_idx + idx_offset);
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/* Pick the right or left neighbor, depending on parity of the node. */
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if (leaf_idx & 1) {
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PQCLEAN_SPHINCSSHA256192FROBUST_CLEAN_thash_2(
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buffer + SPX_N, buffer, pub_seed, addr);
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memcpy(buffer, auth_path, SPX_N);
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} else {
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PQCLEAN_SPHINCSSHA256192FROBUST_CLEAN_thash_2(
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buffer, buffer, pub_seed, addr);
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memcpy(buffer + SPX_N, auth_path, SPX_N);
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}
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auth_path += SPX_N;
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}
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/* The last iteration is exceptional; we do not copy an auth_path node. */
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leaf_idx >>= 1;
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idx_offset >>= 1;
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PQCLEAN_SPHINCSSHA256192FROBUST_CLEAN_set_tree_height(addr, tree_height);
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PQCLEAN_SPHINCSSHA256192FROBUST_CLEAN_set_tree_index(
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addr, leaf_idx + idx_offset);
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PQCLEAN_SPHINCSSHA256192FROBUST_CLEAN_thash_2(
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root, buffer, pub_seed, addr);
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}
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/**
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* For a given leaf index, computes the authentication path and the resulting
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* root node using Merkle's TreeHash algorithm.
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* Expects the layer and tree parts of the tree_addr to be set, as well as the
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* tree type (i.e. SPX_ADDR_TYPE_HASHTREE or SPX_ADDR_TYPE_FORSTREE).
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* Applies the offset idx_offset to indices before building addresses, so that
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* it is possible to continue counting indices across trees.
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*/
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static void PQCLEAN_SPHINCSSHA256192FROBUST_CLEAN_treehash(
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unsigned char *root, unsigned char *auth_path,
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unsigned char *stack, unsigned int *heights,
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const unsigned char *sk_seed, const unsigned char *pub_seed,
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uint32_t leaf_idx, uint32_t idx_offset, uint32_t tree_height,
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void (*gen_leaf)(
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unsigned char * /* leaf */,
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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[8] /* tree_addr */),
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uint32_t tree_addr[8]) {
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unsigned int offset = 0;
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uint32_t idx;
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uint32_t tree_idx;
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for (idx = 0; idx < (uint32_t)(1 << tree_height); idx++) {
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/* Add the next leaf node to the stack. */
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gen_leaf(stack + offset * SPX_N,
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sk_seed, pub_seed, idx + idx_offset, tree_addr);
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offset++;
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heights[offset - 1] = 0;
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/* If this is a node we need for the auth path.. */
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if ((leaf_idx ^ 0x1) == idx) {
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memcpy(auth_path, stack + (offset - 1)*SPX_N, SPX_N);
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}
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/* While the top-most nodes are of equal height.. */
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while (offset >= 2 && heights[offset - 1] == heights[offset - 2]) {
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/* Compute index of the new node, in the next layer. */
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tree_idx = (idx >> (heights[offset - 1] + 1));
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/* Set the address of the node we're creating. */
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PQCLEAN_SPHINCSSHA256192FROBUST_CLEAN_set_tree_height(
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tree_addr, heights[offset - 1] + 1);
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PQCLEAN_SPHINCSSHA256192FROBUST_CLEAN_set_tree_index(
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tree_addr, tree_idx + (idx_offset >> (heights[offset - 1] + 1)));
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/* Hash the top-most nodes from the stack together. */
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PQCLEAN_SPHINCSSHA256192FROBUST_CLEAN_thash_2(
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stack + (offset - 2)*SPX_N, stack + (offset - 2)*SPX_N,
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pub_seed, tree_addr);
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offset--;
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/* Note that the top-most node is now one layer higher. */
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heights[offset - 1]++;
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/* If this is a node we need for the auth path.. */
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if (((leaf_idx >> heights[offset - 1]) ^ 0x1) == tree_idx) {
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memcpy(auth_path + heights[offset - 1]*SPX_N,
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stack + (offset - 1)*SPX_N, SPX_N);
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}
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}
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}
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memcpy(root, stack, SPX_N);
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}
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/* The wrappers below ensure that we use fixed-size buffers on the stack */
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void PQCLEAN_SPHINCSSHA256192FROBUST_CLEAN_treehash_FORS_HEIGHT(
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unsigned char *root, unsigned char *auth_path,
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const unsigned char *sk_seed, const unsigned char *pub_seed,
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uint32_t leaf_idx, uint32_t idx_offset,
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void (*gen_leaf)(
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unsigned char * /* leaf */,
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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[8] /* tree_addr */),
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uint32_t tree_addr[8]) {
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unsigned char stack[(SPX_FORS_HEIGHT + 1)*SPX_N];
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unsigned int heights[SPX_FORS_HEIGHT + 1];
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PQCLEAN_SPHINCSSHA256192FROBUST_CLEAN_treehash(
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root, auth_path, stack, heights, sk_seed, pub_seed,
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leaf_idx, idx_offset, SPX_FORS_HEIGHT, gen_leaf, tree_addr);
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}
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void PQCLEAN_SPHINCSSHA256192FROBUST_CLEAN_treehash_TREE_HEIGHT(
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unsigned char *root, unsigned char *auth_path,
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const unsigned char *sk_seed, const unsigned char *pub_seed,
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uint32_t leaf_idx, uint32_t idx_offset,
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void (*gen_leaf)(
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unsigned char * /* leaf */,
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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[8] /* tree_addr */),
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uint32_t tree_addr[8]) {
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unsigned char stack[(SPX_TREE_HEIGHT + 1)*SPX_N];
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unsigned int heights[SPX_TREE_HEIGHT + 1];
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PQCLEAN_SPHINCSSHA256192FROBUST_CLEAN_treehash(
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root, auth_path, stack, heights, sk_seed, pub_seed,
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leaf_idx, idx_offset, SPX_TREE_HEIGHT, gen_leaf, tree_addr);
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}
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