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Merged
merged 2 commits into from
Jan 2, 2018
Merged

Session key for AES-256-encrypted USB communication #192

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aef8b33
keep standard and hidden wallet passwords in unit tests independent o…
Dec 27, 2017
a18f94f
add session key
Dec 28, 2017
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133 changes: 106 additions & 27 deletions src/commander.c
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Original file line number Diff line number Diff line change
Expand Up @@ -695,7 +695,7 @@ static void commander_process_random(yajl_val json_node)
encoded_report = aes_cbc_b64_encrypt((unsigned char *)echo_number,
strlens(echo_number),
&encrypt_len,
memory_report_aeskey(PASSWORD_VERIFY));
memory_report_verification_key());
if (encoded_report) {
commander_fill_report(cmd_str(CMD_echo), encoded_report, DBB_OK);
free(encoded_report);
Expand Down Expand Up @@ -779,7 +779,7 @@ static void commander_process_verifypass(yajl_val json_node)

if (strlens(value)) {
if (strcmp(value, attr_str(ATTR_export)) == 0) {
memcpy(text, utils_uint8_to_hex(memory_report_aeskey(PASSWORD_VERIFY), 32), 64 + 1);
memcpy(text, utils_uint8_to_hex(memory_report_verification_key(), 32), 64 + 1);
utils_clear_buffers();
int ret = sd_write(VERIFYPASS_FILENAME, text, NULL,
DBB_SD_REPLACE, CMD_verifypass);
Expand Down Expand Up @@ -837,7 +837,7 @@ static void commander_process_verifypass(yajl_val json_node)
char *enc = aes_cbc_b64_encrypt((const unsigned char *)VERIFYPASS_CRYPT_TEST,
strlens(VERIFYPASS_CRYPT_TEST),
&encrypt_len,
memory_report_aeskey(PASSWORD_VERIFY));
memory_report_verification_key());
if (enc) {
snprintf(msg, sizeof(msg), "{\"%s\":\"%s\", \"%s\":\"%s\"}",
cmd_str(CMD_ecdh), utils_uint8_to_hex(out_pubkey, sizeof(out_pubkey)),
Expand Down Expand Up @@ -877,7 +877,7 @@ static void commander_process_xpub(yajl_val json_node)
encoded_report = aes_cbc_b64_encrypt((unsigned char *)xpub,
strlens(xpub),
&encrypt_len,
memory_report_aeskey(PASSWORD_VERIFY));
memory_report_verification_key());
if (encoded_report) {
commander_fill_report(cmd_str(CMD_echo), encoded_report, DBB_OK);
free(encoded_report);
Expand All @@ -903,6 +903,33 @@ static uint8_t commander_bootloader_unlocked(void)
}


static void commander_process_session(yajl_val json_node)
{
const char *path[] = { cmd_str(CMD_session), NULL };
const char *value = YAJL_GET_STRING(yajl_tree_get(json_node, path, yajl_t_string));

if (!strlens(value)) {
commander_fill_report(cmd_str(CMD_session), NULL, DBB_ERR_IO_INVALID_CMD);
return;
}

if (strcmp(value, attr_str(ATTR_set)) == 0) {
commander_fill_report(cmd_str(CMD_session),
utils_uint8_to_hex(memory_session_key_update(),
MEM_PAGE_LEN), DBB_OK);
return;
}

if (strcmp(value, attr_str(ATTR_off)) == 0) {
memory_session_key_off();
commander_fill_report(cmd_str(CMD_session), attr_str(ATTR_success), DBB_OK);
return;
}

commander_fill_report(cmd_str(CMD_session), NULL, DBB_ERR_IO_INVALID_CMD);
}


static void commander_process_device(yajl_val json_node)
{
const char *path[] = { cmd_str(CMD_device), NULL };
Expand Down Expand Up @@ -986,7 +1013,7 @@ static void commander_process_device(yajl_val json_node)
char *tfa = aes_cbc_b64_encrypt((const unsigned char *)VERIFYPASS_CRYPT_TEST,
strlens(VERIFYPASS_CRYPT_TEST),
&tfa_len,
memory_report_aeskey(PASSWORD_VERIFY));
memory_report_verification_key());
if (!tfa) {
commander_clear_report();
commander_fill_report(cmd_str(CMD_device), NULL, DBB_ERR_MEM_ENCRYPT);
Expand Down Expand Up @@ -1148,9 +1175,16 @@ static void commander_process_password(yajl_val json_node, int cmd, PASSWORD_ID

ret = commander_process_aes_key(value, strlens(value), id);

if (!memcmp(memory_report_aeskey(PASSWORD_STAND), memory_report_aeskey(PASSWORD_HIDDEN),
if (!memcmp(memory_read_aeskey(PASSWORD_STAND), memory_read_aeskey(PASSWORD_HIDDEN),
MEM_PAGE_LEN)) {

if (memory_session_key_get_state() == MEM_SESSION_KEY_STATE_STATIC) {
memory_session_key_set(memory_read_aeskey(PASSWORD_STAND));
memory_session_key_off();
}

memory_random_password(PASSWORD_HIDDEN);
memory_clear_passwords();
commander_fill_report(cmd_str(CMD_password), NULL, DBB_ERR_IO_PW_COLLIDE);
return;
}
Expand Down Expand Up @@ -1179,6 +1213,10 @@ static int commander_process(int cmd, yajl_val json_node)
commander_process_password(json_node, cmd, PASSWORD_STAND);
break;

case CMD_session:
commander_process_session(json_node);
break;

case CMD_verifypass:
commander_process_verifypass(json_node);
break;
Expand Down Expand Up @@ -1365,7 +1403,7 @@ static int commander_echo_command(yajl_val json_node)
encoded_report = aes_cbc_b64_encrypt((unsigned char *)json_report,
strlens(json_report),
&encrypt_len,
memory_report_aeskey(PASSWORD_VERIFY));
memory_report_verification_key());
commander_clear_report();
if (encoded_report) {
commander_fill_report(cmd_str(CMD_echo), encoded_report, DBB_OK);
Expand Down Expand Up @@ -1495,8 +1533,11 @@ static void commander_parse(char *command)
encoded_report = aes_cbc_b64_encrypt((unsigned char *)json_report,
strlens(json_report),
&encrypt_len,
wallet_is_hidden() ? memory_report_aeskey(PASSWORD_HIDDEN) : memory_report_aeskey(
PASSWORD_STAND));
memory_session_key_report());

if (memory_session_key_get_state() == MEM_SESSION_KEY_STATE_UPDATING) {
memory_session_key_set(NULL);
}
commander_clear_report();
if (encoded_report) {
commander_fill_report(cmd_str(CMD_ciphertext), encoded_report, DBB_OK);
Expand All @@ -1509,19 +1550,73 @@ static void commander_parse(char *command)
}


static void commander_set_session_key(const char *encrypted_command)
{
char *command;
int command_len = 0;
size_t json_object_len = 0;
uint8_t *key;

// Try standard wallet password
key = memory_read_aeskey(PASSWORD_STAND);
command = aes_cbc_b64_decrypt((const unsigned char *)encrypted_command,
strlens(encrypted_command),
&command_len, key);

if (strlens(command)) {
yajl_val json_node = yajl_tree_parse(command, NULL, 0);
if (json_node && YAJL_IS_OBJECT(json_node)) {
json_object_len = json_node->u.object.len;
}
yajl_tree_free(json_node);
free(command);

if (json_object_len) {
wallet_set_hidden(0);
memory_session_key_set(key);
return;
}
}

// Try hidden wallet password
key = memory_read_aeskey(PASSWORD_HIDDEN);
command = aes_cbc_b64_decrypt((const unsigned char *)encrypted_command,
strlens(encrypted_command),
&command_len, key);

if (strlens(command)) {
yajl_val json_node = yajl_tree_parse(command, NULL, 0);
if (json_node && YAJL_IS_OBJECT(json_node)) {
json_object_len = json_node->u.object.len;
}
yajl_tree_free(json_node);
free(command);

if (json_object_len) {
wallet_set_hidden(1);
memory_session_key_set(key);
return;
}
}
}


static char *commander_decrypt(const char *encrypted_command)
{
char *command;
int command_len = 0, err = 0;
uint16_t err_count = 0, err_iter = 0;
size_t json_object_len = 0;

wallet_set_hidden(0);
if (memory_session_key_get_state() == MEM_SESSION_KEY_STATE_OFF) {
commander_set_session_key(encrypted_command);
memory_clear_passwords();
}

command = aes_cbc_b64_decrypt((const unsigned char *)encrypted_command,
strlens(encrypted_command),
&command_len,
memory_report_aeskey(PASSWORD_STAND));
memory_session_key_report());

err_count = memory_report_access_err_count();
err_iter = memory_report_access_err_count() + 1;
Expand All @@ -1547,22 +1642,6 @@ static char *commander_decrypt(const char *encrypted_command)
free(command);
}

// Check if hidden wallet is requested
command = aes_cbc_b64_decrypt((const unsigned char *)encrypted_command,
strlens(encrypted_command),
&command_len,
memory_report_aeskey(PASSWORD_HIDDEN));
if (strlens(command)) {
yajl_val json_node = yajl_tree_parse(command, NULL, 0);
if (json_node && YAJL_IS_OBJECT(json_node)) {
wallet_set_hidden(1);
yajl_tree_free(json_node);
return command;
}
yajl_tree_free(json_node);
free(command);
}

// Incorrect input
err_iter = memory_access_err_count(DBB_ACCESS_ITERATE);
commander_access_err(DBB_ERR_IO_JSON_PARSE, err_iter);
Expand Down
3 changes: 3 additions & 0 deletions src/flags.h
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Original file line number Diff line number Diff line change
Expand Up @@ -83,6 +83,7 @@ X(REQUIRE_TOUCH) /* placeholder - do not move */\
/* parent keys */\
/* w/o touch */\
X(verifypass) \
X(session) \
X(led) \
X(xpub) \
X(name) \
Expand Down Expand Up @@ -145,6 +146,8 @@ X(unlock) \
X(decrypt) \
X(encrypt) \
X(verify) \
X(set) \
X(off) \
X(true) \
X(false) \
X(erase) \
Expand Down
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