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Small refactoring to avoid unnecessary casts from uint32 to byte strings.

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Signed-off-by: Pol Henarejos <pol.henarejos@cttc.es>
This commit is contained in:
Pol Henarejos
2023-05-25 12:18:28 +02:00
parent b61a34d415
commit 525b05b7ef
1 changed files with 43 additions and 47 deletions
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86
src/hsm/cmd_bip_slip.c
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@@ -24,14 +24,12 @@
const uint8_t *k1_seed = (const uint8_t *)"Bitcoin seed"; const uint8_t *k1_seed = (const uint8_t *)"Bitcoin seed";
const uint8_t *p1_seed = (const uint8_t *)"Nist256p1 seed"; const uint8_t *p1_seed = (const uint8_t *)"Nist256p1 seed";
#define MAX_PATH_DEPTH 16 int node_derive_bip_child(const mbedtls_ecp_keypair *parent, const uint8_t cpar[32], const uint8_t *i, mbedtls_ecp_keypair *child, uint8_t cchild[32]) {
int node_derive_bip_child(const mbedtls_ecp_keypair *parent, const uint8_t cpar[32], uint32_t i, mbedtls_ecp_keypair *child, uint8_t cchild[32]) {
uint8_t data[1+32+4], I[64], *iL = I, *iR = I + 32; uint8_t data[1+32+4], I[64], *iL = I, *iR = I + 32;
mbedtls_mpi il, kchild; mbedtls_mpi il, kchild;
mbedtls_mpi_init(&il); mbedtls_mpi_init(&il);
mbedtls_mpi_init(&kchild); mbedtls_mpi_init(&kchild);
if (i >= 0x80000000) { if (i[0] >= 0x80) {
if (mbedtls_mpi_cmp_int(&parent->d, 0) == 0) { if (mbedtls_mpi_cmp_int(&parent->d, 0) == 0) {
return CCID_ERR_NULL_PARAM; return CCID_ERR_NULL_PARAM;
} }
@@ -43,10 +41,7 @@ int node_derive_bip_child(const mbedtls_ecp_keypair *parent, const uint8_t cpar[
mbedtls_ecp_point_write_binary(&parent->grp, &parent->Q, MBEDTLS_ECP_PF_COMPRESSED, &olen, data, 33); mbedtls_ecp_point_write_binary(&parent->grp, &parent->Q, MBEDTLS_ECP_PF_COMPRESSED, &olen, data, 33);
} }
do { do {
data[33] = i >> 24; memcpy(data + 33, i, 4);
data[34] = i >> 16;
data[35] = i >> 8;
data[36] = i & 0xff;
mbedtls_md_hmac(mbedtls_md_info_from_type(MBEDTLS_MD_SHA512), cpar, 32, data, sizeof(data), I); mbedtls_md_hmac(mbedtls_md_info_from_type(MBEDTLS_MD_SHA512), cpar, 32, data, sizeof(data), I);
mbedtls_mpi_read_binary(&il, iL, 32); mbedtls_mpi_read_binary(&il, iL, 32);
mbedtls_mpi_add_mpi(&kchild, &il, &parent->d); mbedtls_mpi_add_mpi(&kchild, &il, &parent->d);
@@ -72,10 +67,10 @@ int node_fingerprint(mbedtls_ecp_keypair *ctx, uint8_t *fingerprint) {
return CCID_OK; return CCID_OK;
} }
int node_derive_bip_path(const uint32_t *path, size_t path_len, mbedtls_ecp_keypair *ctx, uint8_t chain[32], uint8_t fingerprint[4]) { int load_master_bip(uint32_t mid, mbedtls_ecp_keypair *ctx, uint8_t chain[32]) {
uint8_t mkey[65]; uint8_t mkey[65];
mbedtls_ecp_keypair_init(ctx); mbedtls_ecp_keypair_init(ctx);
file_t *ef = search_dynamic_file(EF_MASTER_SEED | path[0]); file_t *ef = search_dynamic_file(EF_MASTER_SEED | mid);
if (!file_has_data(ef)) { if (!file_has_data(ef)) {
return CCID_ERR_FILE_NOT_FOUND; return CCID_ERR_FILE_NOT_FOUND;
} }
@@ -97,13 +92,37 @@ int node_derive_bip_path(const uint32_t *path, size_t path_len, mbedtls_ecp_keyp
mbedtls_mpi_read_binary(&ctx->d, mkey + 1, 32); mbedtls_mpi_read_binary(&ctx->d, mkey + 1, 32);
memcpy(chain, mkey + 33, 32); memcpy(chain, mkey + 33, 32);
mbedtls_ecp_mul(&ctx->grp, &ctx->Q, &ctx->d, &ctx->grp.G, random_gen, NULL); mbedtls_ecp_mul(&ctx->grp, &ctx->Q, &ctx->d, &ctx->grp.G, random_gen, NULL);
return CCID_OK;
}
int node_derive_bip_path(const uint8_t *path, size_t path_len, mbedtls_ecp_keypair *ctx, uint8_t chain[32], uint8_t fingerprint[4], uint8_t *nodes, uint8_t last_node[4]) {
uint8_t *tag_data = NULL, *p = NULL;
size_t tag_len = 0;
uint16_t tag = 0x0;
uint8_t node = 0;
int r = 0;
memset(last_node, 0, 4);
memset(fingerprint, 0, 4); memset(fingerprint, 0, 4);
for (int ix = 1; ix < path_len; ix++) { for (; walk_tlv(path, path_len, &p, &tag, &tag_len, &tag_data); node++) {
node_fingerprint(ctx, fingerprint); if (tag != 0x02 || (node == 0 && tag_len != 1) || (node != 0 && tag_len != 4)) {
if ((r = node_derive_bip_child(ctx, chain, path[ix], ctx, chain)) != CCID_OK) { return CCID_WRONG_DATA;
}
if (node == 0) {
if ((r = load_master_bip(tag_data[0], ctx, chain)) != CCID_OK) {
return r; return r;
} }
} }
else if (node > 0) {
node_fingerprint(ctx, fingerprint);
if ((r = node_derive_bip_child(ctx, chain, tag_data, ctx, chain)) != CCID_OK) {
return r;
}
memcpy(last_node, tag_data, 4);
}
}
if (nodes) {
*nodes = node;
}
return CCID_OK; return CCID_OK;
} }
@@ -155,28 +174,14 @@ int cmd_bip_slip() {
low_flash_available(); low_flash_available();
} }
else if (p1 == 0x3) { else if (p1 == 0x3) {
uint8_t *tag_data = NULL, *p = NULL;
size_t tag_len = 0;
uint16_t tag = 0x0;
if (apdu.nc == 0) { if (apdu.nc == 0) {
return SW_WRONG_LENGTH(); return SW_WRONG_LENGTH();
} }
uint32_t path[MAX_PATH_DEPTH] = {0}; uint8_t nodes = 0;
uint8_t pos = 0;
for (; walk_tlv(apdu.data, apdu.nc, &p, &tag, &tag_len, &tag_data); pos++) {
if (tag != 0x02 || (pos == 0 && tag_len != 1) || (pos != 0 && tag_len != 4)) {
return SW_WRONG_DATA();
}
if (pos == 0 && tag_len == 1) {
path[pos] = tag_data[0];
}
else if (pos != 0 && tag_len == 4) {
path[pos] = (tag_data[0] << 24) | (tag_data[1] << 16) | (tag_data[2] << 8) | tag_data[3];
}
}
mbedtls_ecp_keypair ctx; mbedtls_ecp_keypair ctx;
uint8_t chain[32], fgpt[4]; uint8_t chain[32], fgpt[4], last_node[4];
int r = node_derive_bip_path(path, pos, &ctx, chain, fgpt); size_t olen = 0;
int r = node_derive_bip_path(apdu.data, apdu.nc, &ctx, chain, fgpt, &nodes, last_node);
if (r != CCID_OK) { if (r != CCID_OK) {
mbedtls_ecp_keypair_free(&ctx); mbedtls_ecp_keypair_free(&ctx);
return SW_EXEC_ERROR(); return SW_EXEC_ERROR();
@@ -184,25 +189,16 @@ int cmd_bip_slip() {
uint8_t pubkey[33]; uint8_t pubkey[33];
memcpy(res_APDU, "\x04\x88\xB2\x1E", 4); memcpy(res_APDU, "\x04\x88\xB2\x1E", 4);
res_APDU_size += 4; res_APDU_size += 4;
res_APDU[res_APDU_size++] = pos - 1; res_APDU[res_APDU_size++] = nodes - 1;
memcpy(res_APDU + res_APDU_size, fgpt, 4); memcpy(res_APDU + res_APDU_size, fgpt, 4);
res_APDU_size += 4; res_APDU_size += 4;
memcpy(res_APDU + res_APDU_size, last_node, 4);
if (pos > 1) {
res_APDU[res_APDU_size++] = path[pos - 1] >> 24;
res_APDU[res_APDU_size++] = path[pos - 1] >> 16;
res_APDU[res_APDU_size++] = path[pos - 1] >> 8;
res_APDU[res_APDU_size++] = path[pos - 1] & 0xff;
}
else { // Master
memset(res_APDU + res_APDU_size, 0, 4);
res_APDU_size += 4; res_APDU_size += 4;
}
memcpy(res_APDU + res_APDU_size, chain, 32); memcpy(res_APDU + res_APDU_size, chain, 32);
res_APDU_size += 32; res_APDU_size += 32;
mbedtls_ecp_point_write_binary(&ctx.grp, &ctx.Q, MBEDTLS_ECP_PF_COMPRESSED, &tag_len, pubkey, sizeof(pubkey)); mbedtls_ecp_point_write_binary(&ctx.grp, &ctx.Q, MBEDTLS_ECP_PF_COMPRESSED, &olen, pubkey, sizeof(pubkey));
memcpy(res_APDU + res_APDU_size, pubkey, tag_len); memcpy(res_APDU + res_APDU_size, pubkey, olen);
res_APDU_size += tag_len; res_APDU_size += olen;
mbedtls_ecp_keypair_free(&ctx); mbedtls_ecp_keypair_free(&ctx);
} }
return SW_OK(); return SW_OK();