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os_bip32.c
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os_bip32.c
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#include <err.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include "os_bip32.h"
#include "bolos/exception.h"
#include "cx.h"
#include "cx_ec.h"
#include "cx_hmac.h"
#include "cx_math.h"
#include "cx_utils.h"
#include "emulate.h"
#define BIP32_HARDEN_MASK 0x80000000
#define BIP32_SECP_SEED_LENGTH 12
#define MAX_SEED_SIZE 64
#define cx_ecfp_generate_pair sys_cx_ecfp_generate_pair
#define cx_ecfp_init_private_key sys_cx_ecfp_init_private_key
#define cx_ecdsa_init_private_key cx_ecfp_init_private_key
/* glory promote mansion idle axis finger extra february uncover one trip
* resource lawn turtle enact monster seven myth punch hobby comfort wild raise
* skin */
static uint8_t default_seed[MAX_SEED_SIZE] =
"\xb1\x19\x97\xfa\xff\x42\x0a\x33\x1b\xb4\xa4\xff\xdc\x8b\xdc\x8b\xa7\xc0"
"\x17\x32\xa9\x9a\x30\xd8\x3d\xbb\xeb\xd4\x69\x66\x6c\x84\xb4\x7d\x09\xd3"
"\xf5\xf4\x72\xb3\xb9\x38\x4a\xc6\x34\xbe\xba\x2a\x44\x0b\xa3\x6e\xc7\x66"
"\x11\x44\x13\x2f\x35\xe2\x06\x87\x35\x64";
static uint8_t const BIP32_SECP_SEED[] = { 'B', 'i', 't', 'c', 'o', 'i',
'n', ' ', 's', 'e', 'e', 'd' };
static uint8_t const BIP32_NIST_SEED[] = { 'N', 'i', 's', 't', '2', '5', '6',
'p', '1', ' ', 's', 'e', 'e', 'd' };
static uint8_t const BIP32_ED_SEED[] = { 'e', 'd', '2', '5', '5', '1',
'9', ' ', 's', 'e', 'e', 'd' };
static uint8_t const SLIP21_SEED[] = { 'S', 'y', 'm', 'm', 'e', 't',
'r', 'i', 'c', ' ', 'k', 'e',
'y', ' ', 's', 'e', 'e', 'd' };
static bool is_hardened_child(uint32_t child)
{
return (child & 0x80000000) != 0;
}
static ssize_t get_seed_key(cx_curve_t curve, const uint8_t **sk)
{
ssize_t sk_length;
switch (curve) {
case CX_CURVE_256K1:
*sk = BIP32_SECP_SEED;
sk_length = sizeof(BIP32_SECP_SEED);
break;
case CX_CURVE_256R1:
*sk = BIP32_NIST_SEED;
sk_length = sizeof(BIP32_NIST_SEED);
break;
case CX_CURVE_Ed25519:
*sk = BIP32_ED_SEED;
sk_length = sizeof(BIP32_ED_SEED);
break;
default:
errx(1, "seed_key: unsupported curve");
sk_length = -1;
break;
}
return sk_length;
}
static ssize_t get_seed_key_slip21(const uint8_t **sk)
{
ssize_t sk_length;
*sk = SLIP21_SEED;
sk_length = sizeof(SLIP21_SEED);
return sk_length;
}
void expand_seed_ed25519(const uint8_t *sk, size_t sk_length, uint8_t *seed,
unsigned int seed_length, extended_private_key *key)
{
uint8_t hash[CX_SHA512_SIZE];
uint8_t buf[1 + MAX_SEED_SIZE];
buf[0] = 0x01;
memcpy(buf + 1, seed, seed_length);
cx_hmac_sha256(sk, sk_length, buf, 1 + seed_length, key->chain_code,
CX_SHA256_SIZE);
cx_hmac_sha512(sk, sk_length, seed, seed_length, hash, CX_SHA512_SIZE);
memcpy(key->private_key, hash, 32);
memcpy(key->chain_code, hash + 32, 32);
while (key->private_key[31] & 0x20) {
cx_hmac_sha512(sk, sk_length, key->private_key, CX_SHA512_SIZE,
key->private_key, CX_SHA512_SIZE);
}
key->private_key[0] &= 0xF8;
key->private_key[31] = (key->private_key[31] & 0x7F) | 0x40;
}
void expand_seed_slip10(const uint8_t *sk, size_t sk_length, uint8_t *seed,
unsigned int seed_length, extended_private_key *key)
{
uint8_t hash[CX_SHA512_SIZE];
cx_hmac_sha512(sk, sk_length, seed, seed_length, hash, CX_SHA512_SIZE);
memcpy(key->private_key, hash, 32);
memcpy(key->chain_code, hash + 32, 32);
}
void expand_seed_ed25519_bip32(const uint8_t *sk, size_t sk_length,
uint8_t *seed, unsigned int seed_length,
extended_private_key *key)
{
uint8_t buf[1 + MAX_SEED_SIZE];
buf[0] = 0x01;
memcpy(buf + 1, seed, seed_length);
cx_hmac_sha256(sk, sk_length, buf, 1 + seed_length, key->chain_code,
CX_SHA256_SIZE);
cx_hmac_sha512(sk, sk_length, seed, seed_length, key->private_key,
CX_SHA512_SIZE);
while (key->private_key[31] & 0x20) {
cx_hmac_sha512(sk, sk_length, key->private_key, CX_SHA512_SIZE,
key->private_key, CX_SHA512_SIZE);
}
key->private_key[0] &= 0xF8;
key->private_key[31] = (key->private_key[31] & 0x7F) | 0x40;
}
static void expand_seed(cx_curve_t curve, const uint8_t *sk, size_t sk_length,
uint8_t *seed, unsigned int seed_length,
extended_private_key *key)
{
const cx_curve_domain_t *domain;
uint8_t hash[CX_SHA512_SIZE];
domain = cx_ecfp_get_domain(curve);
cx_hmac_sha512(sk, sk_length, seed, seed_length, hash, CX_SHA512_SIZE);
memcpy(key->private_key, hash, 32);
memcpy(key->chain_code, hash + 32, 32);
/* ensure that the master key is valid */
while (cx_math_is_zero(key->private_key, 32) ||
cx_math_cmp(key->private_key, domain->n, 32) >= 0) {
memcpy(hash, key->private_key, 32);
memcpy(hash + 32, key->chain_code, 32);
cx_hmac_sha512(sk, sk_length, hash, CX_SHA512_SIZE, hash, CX_SHA512_SIZE);
memcpy(key->private_key, hash, 32);
memcpy(key->chain_code, hash + 32, 32);
}
}
int unhex(uint8_t *dst, size_t dst_size, const char *src, size_t src_size)
{
unsigned int i;
uint8_t acc;
int8_t c;
acc = 0;
for (i = 0; i < src_size && (i >> 1) < dst_size; i++) {
c = src[i];
switch (c) {
case '0' ... '9':
acc = (acc << 4) + c - '0';
break;
case 'a' ... 'f':
acc = (acc << 4) + c - 'a' + 10;
break;
case 'A' ... 'F':
acc = (acc << 4) + c - 'A' + 10;
break;
default:
return -1;
}
if (i % 2 != 0) {
dst[i >> 1] = acc;
acc = 0;
}
}
if (i != src_size) {
return -1;
}
return src_size / 2;
}
size_t get_seed_from_env(const char *name, uint8_t *seed, size_t max_size)
{
ssize_t seed_size;
char *p;
p = getenv(name);
if (p != NULL) {
seed_size = unhex(seed, max_size, p, strlen(p));
if (seed_size < 0) {
warnx("invalid seed passed through %s environment variable", name);
p = NULL;
}
}
if (p == NULL) {
warnx("using default seed");
memcpy(seed, default_seed, sizeof(default_seed));
seed_size = sizeof(default_seed);
}
return seed_size;
}
static int hdw_bip32_ed25519(extended_private_key *key, const uint32_t *path,
size_t length, uint8_t *private_key,
uint8_t *chain)
{
const cx_curve_domain_t *domain;
cx_ecfp_256_public_key_t pub;
uint8_t *kP, *kLP, *kRP;
unsigned int i, j, len;
uint8_t tmp[1 + 64 + 4], x;
uint8_t *ZR, *Z, *ZL;
Z = tmp + 1;
ZL = tmp + 1;
ZR = tmp + 1 + 32;
kP = key->private_key;
kLP = key->private_key;
kRP = &key->private_key[32];
domain = cx_ecfp_get_domain(CX_CURVE_Ed25519);
pub.W_len = 65;
pub.W[0] = 0x04;
for (i = 0; i < length; i++) {
// compute the public key A = kL.G
memcpy(pub.W + 1, domain->Gx, 32);
memcpy(pub.W + 1 + 32, domain->Gy, 32);
le2be(kLP, 32);
sys_cx_ecfp_scalar_mult(CX_CURVE_Ed25519, pub.W, pub.W_len, kLP, 32);
be2le(kLP, 32);
sys_cx_edward_compress_point(CX_CURVE_Ed25519, pub.W, pub.W_len);
// Step 1: compute kL/Kr child
// if less than 0x80000000 => setup 02|A|i in tmp
if (!is_hardened_child(path[i])) {
tmp[0] = 0x02;
memcpy(tmp + 1, &pub.W[1], 32);
len = 1 + 32;
} else {
// else if greater-eq than 0x80000000 --> setup 00|k|i in tmp
tmp[0] = 0x00;
memcpy(tmp + 1, kP, 64);
len = 1 + 32 * 2;
}
tmp[len + 0] = (path[i] >> 0) & 0xff;
tmp[len + 1] = (path[i] >> 8) & 0xff;
tmp[len + 2] = (path[i] >> 16) & 0xff;
tmp[len + 3] = (path[i] >> 24) & 0xff;
len += 4;
// compute Z = Hmac(...)
cx_hmac_sha512(key->chain_code, 32, tmp, len, Z, CX_SHA512_SIZE);
// kL = 8*Zl + kLP (use multm, but never overflow order, so ok)
le2be(ZL, 32);
le2be(kLP, 32);
memset(ZL, 0, 4);
cx_math_add(ZL, ZL, ZL, 32);
cx_math_add(ZL, ZL, ZL, 32);
cx_math_add(ZL, ZL, ZL, 32);
cx_math_add(ZL, ZL, kLP, 32);
be2le(ZL, 32);
be2le(kLP, 32);
// kR = Zr + kRP
le2be(ZR, 32);
le2be(kRP, 32);
cx_math_add(ZR, ZR, kRP, 32);
be2le(ZR, 32);
be2le(kRP, 32);
// store new kL,kP, but keep old on to compute new c
for (j = 0; j < 64; j++) {
x = kP[j];
kP[j] = Z[j];
Z[j] = x;
}
// Step2: compute chain code
// if less than 0x80000000 => set up 03|A|i in tmp
if (!is_hardened_child(path[i])) {
tmp[0] = 0x03;
memcpy(tmp + 1, &pub.W[1], 32);
len = 1 + 32;
}
// else if greater-eq than 0x80000000 --> 01|k|i in tmp
else {
tmp[0] = 0x01;
// kP already set
len = 1 + 32 * 2;
}
tmp[len + 0] = (path[i] >> 0) & 0xff;
tmp[len + 1] = (path[i] >> 8) & 0xff;
tmp[len + 2] = (path[i] >> 16) & 0xff;
tmp[len + 3] = (path[i] >> 24) & 0xff;
len += 4;
cx_hmac_sha512(key->chain_code, 32, tmp, len, tmp, CX_SHA512_SIZE);
// store new c
memcpy(key->chain_code, tmp + 32, 32);
}
if (private_key != NULL) {
memcpy(private_key, kP, 64);
}
if (chain != NULL) {
memcpy(chain, key->chain_code, 32);
}
return 0;
}
static int hdw_slip10(extended_private_key *key, const uint32_t *path,
size_t length, uint8_t *private_key, uint8_t *chain)
{
uint8_t tmp[1 + 64 + 4];
unsigned int i;
for (i = 0; i < length; i++) {
if (is_hardened_child(path[i])) {
tmp[0] = 0;
memcpy(tmp + 1, key->private_key, 32);
} else {
warn("hdw_slip10: invalid path (%u:0x%x)", i, path[i]);
return -1;
}
tmp[33] = (path[i] >> 24) & 0xff;
tmp[34] = (path[i] >> 16) & 0xff;
tmp[35] = (path[i] >> 8) & 0xff;
tmp[36] = path[i] & 0xff;
cx_hmac_sha512(key->chain_code, 32, tmp, 37, tmp, CX_SHA512_SIZE);
memcpy(key->private_key, tmp, 32);
memcpy(key->chain_code, tmp + 32, 32);
}
if (private_key != NULL) {
memcpy(private_key, key->private_key, 32);
}
if (chain != NULL) {
memcpy(chain, key->chain_code, 32);
}
return 0;
}
static int hdw_bip32(extended_private_key *key, cx_curve_t curve,
const uint32_t *path, size_t length, uint8_t *private_key,
uint8_t *chain)
{
const cx_curve_domain_t *domain;
cx_ecfp_256_public_key_t pub;
cx_ecfp_private_key_t priv;
uint8_t tmp[1 + 64 + 4];
unsigned int i;
if (curve != CX_CURVE_256K1 && curve != CX_CURVE_SECP256R1) {
warn("hdw_bip32: invalid curve (0x%x)", curve);
return -1;
}
domain = cx_ecfp_get_domain(curve);
for (i = 0; i < length; i++) {
if (is_hardened_child(path[i])) {
tmp[0] = 0;
memcpy(tmp + 1, key->private_key, 32);
} else {
cx_ecdsa_init_private_key(curve, key->private_key, 32, &priv);
cx_ecfp_generate_pair(curve, &pub, &priv, 1);
pub.W[0] = (pub.W[64] & 1) ? 0x03 : 0x02;
memcpy(tmp, pub.W, 33);
}
while (true) {
tmp[33] = (path[i] >> 24) & 0xff;
tmp[34] = (path[i] >> 16) & 0xff;
tmp[35] = (path[i] >> 8) & 0xff;
tmp[36] = path[i] & 0xff;
cx_hmac_sha512(key->chain_code, 32, tmp, 37, tmp, CX_SHA512_SIZE);
if (cx_math_cmp(tmp, domain->n, 32) < 0) {
cx_math_addm(tmp, tmp, key->private_key, domain->n, 32);
if (cx_math_is_zero(tmp, 32) == 0) {
break;
}
}
tmp[0] = 1;
memmove(tmp + 1, tmp + 32, 32);
}
memcpy(key->private_key, tmp, 32);
memcpy(key->chain_code, tmp + 32, 32);
}
if (private_key != NULL) {
memcpy(private_key, key->private_key, 32);
}
if (chain != NULL) {
memcpy(chain, key->chain_code, 32);
}
return 0;
}
static int hdw_slip21(const uint8_t *sk, size_t sk_length, const uint8_t *seed,
size_t seed_size, const uint8_t *path, size_t path_len,
uint8_t *private_key)
{
uint8_t node[CX_SHA512_SIZE];
if (path == NULL || path_len == 0 || path[0] != 0) {
warnx("hdw_slip21: invalid path");
return -1;
}
/* derive master node */
cx_hmac_sha512(sk, sk_length, seed, seed_size, node, CX_SHA512_SIZE);
/* derive child node */
cx_hmac_sha512(node, 32, path, path_len, node, CX_SHA512_SIZE);
if (private_key != NULL) {
memcpy(private_key, node + 32, 32);
}
return 0;
}
unsigned long sys_os_perso_derive_node_bip32_seed_key(
unsigned int mode, cx_curve_t curve, const unsigned int *path,
unsigned int pathLength, unsigned char *privateKey, unsigned char *chain,
unsigned char *seed_key, unsigned int seed_key_length)
__attribute__((weak, alias("sys_os_perso_derive_node_with_seed_key")));
unsigned long sys_os_perso_derive_node_with_seed_key(
unsigned int mode, cx_curve_t curve, const unsigned int *path,
unsigned int pathLength, unsigned char *privateKey, unsigned char *chain,
unsigned char *seed_key, unsigned int seed_key_length)
{
ssize_t sk_length;
size_t seed_size;
uint8_t seed[MAX_SEED_SIZE];
extended_private_key key;
const uint8_t *sk;
int ret;
// In SDK2, some curves don't have the same value:
switch ((int)curve) {
case 0x71:
curve = CX_CURVE_Ed25519;
break;
case 0x72:
curve = CX_CURVE_Ed448;
break;
case 0x81:
curve = CX_CURVE_Curve25519;
break;
case 0x82:
curve = CX_CURVE_Curve448;
break;
}
if (seed_key == NULL || seed_key_length == 0) {
if (mode != HDW_SLIP21) {
sk_length = get_seed_key(curve, &sk);
} else {
sk_length = get_seed_key_slip21(&sk);
}
if (sk_length < 0) {
THROW(EXCEPTION);
}
} else {
sk = seed_key;
sk_length = seed_key_length;
}
seed_size = get_seed_from_env("SPECULOS_SEED", seed, sizeof(seed));
if (mode == HDW_SLIP21) {
ret = hdw_slip21(sk, sk_length, seed, seed_size, (const uint8_t *)path,
pathLength, privateKey);
} else if (mode == HDW_ED25519_SLIP10) {
/* https://github.com/satoshilabs/slips/tree/master/slip-0010 */
/* https://github.com/satoshilabs/slips/blob/master/slip-0010.md */
if (curve == CX_CURVE_Ed25519) {
expand_seed_slip10(sk, sk_length, seed, seed_size, &key);
ret = hdw_slip10(&key, path, pathLength, privateKey, chain);
} else {
expand_seed(curve, sk, sk_length, seed, seed_size, &key);
ret = hdw_bip32(&key, curve, path, pathLength, privateKey, chain);
}
} else {
if (curve == CX_CURVE_Ed25519) {
expand_seed_ed25519_bip32(sk, sk_length, seed, seed_size, &key);
ret = hdw_bip32_ed25519(&key, path, pathLength, privateKey, chain);
} else {
expand_seed(curve, sk, sk_length, seed, seed_size, &key);
ret = hdw_bip32(&key, curve, path, pathLength, privateKey, chain);
}
}
if (ret < 0) {
THROW(EXCEPTION);
}
return 0;
}
unsigned long sys_os_perso_derive_node_bip32(cx_curve_t curve,
const uint32_t *path,
size_t length,
uint8_t *private_key,
uint8_t *chain)
{
return sys_os_perso_derive_node_with_seed_key(HDW_NORMAL, curve, path, length,
private_key, chain, NULL, 0);
}