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Diffstat (limited to 'src/crypto/spx/merkle.c')
-rw-r--r-- | src/crypto/spx/merkle.c | 150 |
1 files changed, 150 insertions, 0 deletions
diff --git a/src/crypto/spx/merkle.c b/src/crypto/spx/merkle.c new file mode 100644 index 0000000..58429f7 --- /dev/null +++ b/src/crypto/spx/merkle.c @@ -0,0 +1,150 @@ +/* Copyright (c) 2023, Google LLC + * + * Permission to use, copy, modify, and/or distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY + * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION + * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN + * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ + +#include <openssl/base.h> + +#include <string.h> + +#include "./address.h" +#include "./merkle.h" +#include "./params.h" +#include "./thash.h" +#include "./wots.h" + +void spx_treehash(uint8_t out_pk[SPX_N], const uint8_t sk_seed[SPX_N], + uint32_t i /*target node index*/, + uint32_t z /*target node height*/, + const uint8_t pk_seed[SPX_N], uint8_t addr[32]) { + BSSL_CHECK(z <= SPX_TREE_HEIGHT); + BSSL_CHECK(i < (uint32_t)(1 << (SPX_TREE_HEIGHT - z))); + + if (z == 0) { + spx_set_type(addr, SPX_ADDR_TYPE_WOTS); + spx_set_keypair_addr(addr, i); + spx_wots_pk_gen(out_pk, sk_seed, pk_seed, addr); + } else { + // Stores left node and right node. + uint8_t nodes[2 * SPX_N]; + spx_treehash(nodes, sk_seed, 2 * i, z - 1, pk_seed, addr); + spx_treehash(nodes + SPX_N, sk_seed, 2 * i + 1, z - 1, pk_seed, addr); + spx_set_type(addr, SPX_ADDR_TYPE_HASHTREE); + spx_set_tree_height(addr, z); + spx_set_tree_index(addr, i); + spx_thash_h(out_pk, nodes, pk_seed, addr); + } +} + +void spx_xmss_sign(uint8_t *sig, const uint8_t msg[SPX_N], unsigned int idx, + const uint8_t sk_seed[SPX_N], const uint8_t pk_seed[SPX_N], + uint8_t addr[32]) { + // Build authentication path + for (size_t j = 0; j < SPX_TREE_HEIGHT; ++j) { + unsigned int k = (idx >> j) ^ 1; + spx_treehash(sig + SPX_WOTS_BYTES + j * SPX_N, sk_seed, k, j, pk_seed, + addr); + } + + // Compute WOTS+ signature + spx_set_type(addr, SPX_ADDR_TYPE_WOTS); + spx_set_keypair_addr(addr, idx); + spx_wots_sign(sig, msg, sk_seed, pk_seed, addr); +} + +void spx_xmss_pk_from_sig(uint8_t *root, const uint8_t *xmss_sig, + unsigned int idx, const uint8_t msg[SPX_N], + const uint8_t pk_seed[SPX_N], uint8_t addr[32]) { + // Stores node[0] and node[1] from Algorithm 10 + uint8_t node[2 * SPX_N]; + uint8_t tmp[2 * SPX_N]; + spx_set_type(addr, SPX_ADDR_TYPE_WOTS); + spx_set_keypair_addr(addr, idx); + spx_wots_pk_from_sig(node, xmss_sig, msg, pk_seed, addr); + + const uint8_t *auth = xmss_sig + SPX_WOTS_BYTES; + + spx_set_type(addr, SPX_ADDR_TYPE_HASHTREE); + spx_set_tree_index(addr, idx); + for (size_t k = 0; k < SPX_TREE_HEIGHT; ++k) { + spx_set_tree_height(addr, k + 1); + // Is even + if (((idx >> k) & 1) == 0) { + spx_set_tree_index(addr, spx_get_tree_index(addr) >> 1); + memcpy(tmp, node, SPX_N); + memcpy(tmp + SPX_N, auth + k * SPX_N, SPX_N); + spx_thash_h(node + SPX_N, tmp, pk_seed, addr); + } else { + spx_set_tree_index(addr, (spx_get_tree_index(addr) - 1) >> 1); + memcpy(tmp, auth + k * SPX_N, SPX_N); + memcpy(tmp + SPX_N, node, SPX_N); + spx_thash_h(node + SPX_N, tmp, pk_seed, addr); + } + memcpy(node, node + SPX_N, SPX_N); + } + memcpy(root, node, SPX_N); +} + +void spx_ht_sign(uint8_t *sig, const uint8_t message[SPX_N], uint64_t idx_tree, + uint32_t idx_leaf, const uint8_t sk_seed[SPX_N], + const uint8_t pk_seed[SPX_N]) { + uint8_t addr[32] = {0}; + spx_set_tree_addr(addr, idx_tree); + + // Layer 0 + uint8_t sig_tmp[SPX_XMSS_BYTES]; + spx_xmss_sign(sig_tmp, message, idx_leaf, sk_seed, pk_seed, addr); + memcpy(sig, sig_tmp, sizeof(sig_tmp)); + + uint8_t root[SPX_N]; + spx_xmss_pk_from_sig(root, sig_tmp, idx_leaf, message, pk_seed, addr); + + // All other layers + for (size_t j = 1; j < SPX_D; ++j) { + idx_leaf = idx_tree % (1 << SPX_TREE_HEIGHT); + idx_tree = idx_tree >> SPX_TREE_HEIGHT; + spx_set_layer_addr(addr, j); + spx_set_tree_addr(addr, idx_tree); + spx_xmss_sign(sig_tmp, root, idx_leaf, sk_seed, pk_seed, addr); + memcpy(sig + j * SPX_XMSS_BYTES, sig_tmp, sizeof(sig_tmp)); + + if (j < (SPX_D - 1)) { + spx_xmss_pk_from_sig(root, sig_tmp, idx_leaf, root, pk_seed, addr); + } + } +} + +int spx_ht_verify(const uint8_t sig[SPX_D * SPX_XMSS_BYTES], + const uint8_t message[SPX_N], uint64_t idx_tree, + uint32_t idx_leaf, const uint8_t pk_root[SPX_N], + const uint8_t pk_seed[SPX_N]) { + uint8_t addr[32] = {0}; + spx_set_tree_addr(addr, idx_tree); + + uint8_t sig_tmp[SPX_XMSS_BYTES]; + memcpy(sig_tmp, sig, sizeof(sig_tmp)); + + uint8_t node[SPX_N]; + spx_xmss_pk_from_sig(node, sig_tmp, idx_leaf, message, pk_seed, addr); + + for (size_t j = 1; j < SPX_D; ++j) { + idx_leaf = idx_tree % (1 << SPX_TREE_HEIGHT); + idx_tree = idx_tree >> SPX_TREE_HEIGHT; + spx_set_layer_addr(addr, j); + spx_set_tree_addr(addr, idx_tree); + // Get jth XMSS signature + memcpy(sig_tmp, sig + j * SPX_XMSS_BYTES, sizeof(sig_tmp)); + + spx_xmss_pk_from_sig(node, sig_tmp, idx_leaf, node, pk_seed, addr); + } + return memcmp(node, pk_root, SPX_N) == 0; +} |