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Remove magic constants

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Use defines for wallet depth and change chain.  Updated some comments
to clarify what is checked.
This commit is contained in:
Jochen Hoenicke 2017-10-30 12:20:47 +01:00 committed by Pavol Rusnak
parent 4805f27e8c
commit a24e8a0484
1 changed files with 25 additions and 13 deletions
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38
firmware/signing.c
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@ -68,11 +68,16 @@ static uint8_t multisig_fp[32];
static uint32_t in_address_n[8]; static uint32_t in_address_n[8];
static size_t in_address_n_count; static size_t in_address_n_count;
/* marker for in_address_n_count to indicate a mismatch in bip32 paths in /* A marker for in_address_n_count to indicate a mismatch in bip32 paths in
input */ input */
#define BIP32_NOCHANGEALLOWED 1 #define BIP32_NOCHANGEALLOWED 1
/* maximum allowed change index */ /* The number of bip32 levels used in a wallet (chain and address) */
#define MAX_BIP32_LAST_ELEMENT 1000000 #define BIP32_WALLET_DEPTH 2
/* The chain id used for change */
#define BIP32_CHANGE_CHAIN 1
/* The maximum allowed change address. This should be large enough for normal
use and still allow to quickly brute-force the correct bip32 path. */
#define BIP32_MAX_LAST_ELEMENT 1000000
enum { enum {
SIGHASH_ALL = 1, SIGHASH_ALL = 1,
@ -338,7 +343,7 @@ void extract_input_bip32_path(const TxInputType *tinput)
return; return;
} }
size_t count = tinput->address_n_count; size_t count = tinput->address_n_count;
if (count < 2) { if (count < BIP32_WALLET_DEPTH) {
// no change address allowed // no change address allowed
in_address_n_count = BIP32_NOCHANGEALLOWED; in_address_n_count = BIP32_NOCHANGEALLOWED;
return; return;
@ -346,16 +351,19 @@ void extract_input_bip32_path(const TxInputType *tinput)
if (in_address_n_count == 0) { if (in_address_n_count == 0) {
// initialize in_address_n on first input seen // initialize in_address_n on first input seen
in_address_n_count = count; in_address_n_count = count;
// store first N - 2 // store the bip32 path up to the account
memcpy(in_address_n, tinput->address_n, (count - 2) * sizeof(uint32_t)); memcpy(in_address_n, tinput->address_n,
(count - BIP32_WALLET_DEPTH) * sizeof(uint32_t));
return; return;
} }
// check whether they are same length // check that all addresses use a path of same length
if (in_address_n_count != count) { if (in_address_n_count != count) {
in_address_n_count = BIP32_NOCHANGEALLOWED; in_address_n_count = BIP32_NOCHANGEALLOWED;
return; return;
} }
if (memcmp(in_address_n, tinput->address_n, (count - 2) * sizeof(uint32_t)) != 0) { // check that the bip32 path up to the account matches
if (memcmp(in_address_n, tinput->address_n,
(count - BIP32_WALLET_DEPTH) * sizeof(uint32_t)) != 0) {
// mismatch -> no change address allowed // mismatch -> no change address allowed
in_address_n_count = BIP32_NOCHANGEALLOWED; in_address_n_count = BIP32_NOCHANGEALLOWED;
return; return;
@ -366,13 +374,17 @@ bool check_change_bip32_path(const TxOutputType *toutput)
{ {
size_t count = toutput->address_n_count; size_t count = toutput->address_n_count;
// Note: count >= 2 and count == in_address_n_count // Check that the change path has the same bip32 path length,
// the same path up to the account, and that the wallet components
// (chain id and address) are as expected.
// Note: count >= BIP32_WALLET_DEPTH and count == in_address_n_count
// imply that in_address_n_count != BIP32_NOCHANGEALLOWED // imply that in_address_n_count != BIP32_NOCHANGEALLOWED
return (count >= 2 return (count >= BIP32_WALLET_DEPTH
&& count == in_address_n_count && count == in_address_n_count
&& 0 == memcmp(in_address_n, toutput->address_n, (count - 2) * sizeof(uint32_t)) && 0 == memcmp(in_address_n, toutput->address_n,
&& toutput->address_n[count - 2] == 1 (count - BIP32_WALLET_DEPTH) * sizeof(uint32_t))
&& toutput->address_n[count - 1] <= MAX_BIP32_LAST_ELEMENT); && toutput->address_n[count - 2] == BIP32_CHANGE_CHAIN
&& toutput->address_n[count - 1] <= BIP32_MAX_LAST_ELEMENT);
} }
bool compile_input_script_sig(TxInputType *tinput) bool compile_input_script_sig(TxInputType *tinput)