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mnemonic: support all standard BIP39 word counts #314

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1 change: 1 addition & 0 deletions main/amalgamated.c
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@ void __wrap_abort(void);
#include "./assets.c"
#include "./attestation/attestation.c"
#include "./bcur.c"
#include "./bip39.c"
#ifdef CONFIG_BT_ENABLED
#include "./ble/ble.c"
#endif // CONFIG_BT_ENABLED
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2 changes: 1 addition & 1 deletion main/bcur.c
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Original file line number Diff line number Diff line change
Expand Up @@ -100,7 +100,7 @@ bool bcur_parse_bip39(
}
size_t num_words = 0;
cberr = cbor_value_get_array_length(&mapItem, &num_words);
if (cberr != CborNoError || (num_words != 12 && num_words != 24) || !cbor_value_is_container(&mapItem)) {
if (cberr != CborNoError || !jade_bip39_word_count_valid(num_words) || !cbor_value_is_container(&mapItem)) {
return false;
}
CborValue arrayItem;
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57 changes: 57 additions & 0 deletions main/bip39.c
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Original file line number Diff line number Diff line change
@@ -0,0 +1,57 @@
#ifndef AMALGAMATED_BUILD
#include "bip39.h"
#include "jade_wally_verify.h"

#include <wally_bip39.h>

size_t jade_bip39_entropy_len_from_word_count(const size_t nwords)
{
switch (nwords) {
case 12:
return BIP39_ENTROPY_LEN_128;
case 15:
return BIP39_ENTROPY_LEN_160;
case 18:
return BIP39_ENTROPY_LEN_192;
case 21:
return BIP39_ENTROPY_LEN_224;
case 24:
return BIP39_ENTROPY_LEN_256;
default:
return 0;
}
}

size_t jade_bip39_word_count_from_entropy_len(const size_t entropy_len)
{
switch (entropy_len) {
case BIP39_ENTROPY_LEN_128:
return 12;
case BIP39_ENTROPY_LEN_160:
return 15;
case BIP39_ENTROPY_LEN_192:
return 18;
case BIP39_ENTROPY_LEN_224:
return 21;
case BIP39_ENTROPY_LEN_256:
return 24;
default:
return 0;
}
}

bool jade_bip39_word_count_valid(const size_t nwords) { return jade_bip39_entropy_len_from_word_count(nwords) != 0; }

bool jade_bip39_mnemonic_validate(const char* mnemonic)
{
if (!mnemonic) {
return false;
}

uint8_t entropy[BIP39_ENTROPY_LEN_256];
size_t entropy_len = 0;
const int wret = bip39_mnemonic_to_bytes(NULL, mnemonic, entropy, sizeof(entropy), &entropy_len);
JADE_WALLY_VERIFY(wally_bzero(entropy, sizeof(entropy)));
return wret == WALLY_OK && jade_bip39_word_count_from_entropy_len(entropy_len) != 0;
}
#endif // AMALGAMATED_BUILD
21 changes: 21 additions & 0 deletions main/bip39.h
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@@ -0,0 +1,21 @@
#ifndef JADE_BIP39_H_
#define JADE_BIP39_H_

#include <stdbool.h>
#include <stddef.h>

// Jade supports the standard BIP39 English mnemonic lengths.
#define MNEMONIC_MAXWORDS 24

// The longest valid words in the English wordlist are 8 characters.
#define MNEMONIC_MAX_WORD_LEN 8

// 24 8-character words + 23 spaces + NUL = 216 bytes.
#define MNEMONIC_BUFLEN 216

size_t jade_bip39_entropy_len_from_word_count(size_t nwords);
size_t jade_bip39_word_count_from_entropy_len(size_t entropy_len);
bool jade_bip39_word_count_valid(size_t nwords);
bool jade_bip39_mnemonic_validate(const char* mnemonic);

#endif /* JADE_BIP39_H_ */
8 changes: 8 additions & 0 deletions main/button_events.h
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Expand Up @@ -61,7 +61,11 @@ typedef enum {

BTN_NEW_MNEMONIC,
BTN_NEW_MNEMONIC_12,
BTN_NEW_MNEMONIC_15,
BTN_NEW_MNEMONIC_18,
BTN_NEW_MNEMONIC_21,
BTN_NEW_MNEMONIC_24,
BTN_NEW_MNEMONIC_MORE,

BTN_MNEMONIC_PREV,
BTN_MNEMONIC_NEXT,
Expand All @@ -70,7 +74,11 @@ typedef enum {

BTN_RESTORE_MNEMONIC,
BTN_RESTORE_MNEMONIC_12,
BTN_RESTORE_MNEMONIC_15,
BTN_RESTORE_MNEMONIC_18,
BTN_RESTORE_MNEMONIC_21,
BTN_RESTORE_MNEMONIC_24,
BTN_RESTORE_MNEMONIC_MORE,
BTN_RESTORE_MNEMONIC_QR,

BTN_MNEMONIC_FINAL_WORD_EXISTING,
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22 changes: 10 additions & 12 deletions main/keychain.c
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
#ifndef AMALGAMATED_BUILD
#include "keychain.h"
#include "aes.h"
#include "bip39.h"
#include "jade_assert.h"
#include "jade_wally_verify.h"
#include "random.h"
Expand Down Expand Up @@ -194,8 +195,7 @@ void keychain_cache_mnemonic_entropy(const char* mnemonic)
JADE_WALLY_VERIFY(
bip39_mnemonic_to_bytes(NULL, mnemonic, mnemonic_entropy, sizeof(mnemonic_entropy), &mnemonic_entropy_len));

// Only 12 or 24 word mnemonics are supported
JADE_ASSERT(mnemonic_entropy_len == BIP39_ENTROPY_LEN_128 || mnemonic_entropy_len == BIP39_ENTROPY_LEN_256);
JADE_ASSERT(jade_bip39_word_count_from_entropy_len(mnemonic_entropy_len));
}

// Clear the network type restriction
Expand Down Expand Up @@ -270,14 +270,13 @@ void keychain_get_new_mnemonic(char** mnemonic, const size_t nwords)
{
JADE_INIT_OUT_PPTR(mnemonic);

// Support 12-word and 24-word mnemonics only
JADE_ASSERT(nwords == 12 || nwords == 24);
JADE_ASSERT(jade_bip39_word_count_valid(nwords));

// Large enough for 12 and 24 word mnemonic
// Large enough for any standard BIP39 mnemonic.
uint8_t entropy[BIP39_ENTROPY_LEN_256];
SENSITIVE_PUSH(entropy, sizeof(entropy));

const size_t entropy_len = nwords == 12 ? BIP39_ENTROPY_LEN_128 : BIP39_ENTROPY_LEN_256;
const size_t entropy_len = jade_bip39_entropy_len_from_word_count(nwords);
get_random(entropy, entropy_len);
const int wret = bip39_mnemonic_from_bytes(NULL, entropy, entropy_len, mnemonic);
SENSITIVE_POP(entropy);
Expand Down Expand Up @@ -328,8 +327,8 @@ bool keychain_derive_from_mnemonic(const char* mnemonic, const char* passphrase,
}
}

// Mnemonic must be valid
if (bip39_mnemonic_validate(NULL, mnemonic) != WALLY_OK) {
// Mnemonic must have a valid checksum and a standard BIP39 word count.
if (!jade_bip39_mnemonic_validate(mnemonic)) {
JADE_LOGE("Invalid mnemonic");
return false;
}
Expand Down Expand Up @@ -557,8 +556,7 @@ bool keychain_store(const uint8_t* aeskey, const size_t aeslen)
// 1. Get serialised data to encrypt/persist
if (mnemonic_entropy_len) {
// Use mnemonic entropy
// Only 12 or 24 word mnemonics are supported
JADE_ASSERT(mnemonic_entropy_len == BIP39_ENTROPY_LEN_128 || mnemonic_entropy_len == BIP39_ENTROPY_LEN_256);
JADE_ASSERT(jade_bip39_word_count_from_entropy_len(mnemonic_entropy_len));
JADE_ASSERT(mnemonic_entropy_len <= sizeof(mnemonic_entropy));
JADE_ASSERT(mnemonic_entropy_len < sizeof(serialized));
p_serialized_data = mnemonic_entropy;
Expand Down Expand Up @@ -613,8 +611,8 @@ bool keychain_load(const uint8_t* aeskey, const size_t aeslen)
}

// 2. Cache mnemonic entropy or deserialise keychain
if (serialized_data_len == BIP39_ENTROPY_LEN_128 || serialized_data_len == BIP39_ENTROPY_LEN_256) {
// Write mnemonic entropy - only 12 or 24 word mnemonics are supported
if (jade_bip39_word_count_from_entropy_len(serialized_data_len)) {
// Write mnemonic entropy.
memcpy(mnemonic_entropy, serialized, serialized_data_len);
mnemonic_entropy_len = serialized_data_len;
} else if (serialized_data_len == SERIALIZED_KEY_LEN) {
Expand Down
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