def decrypt_rx_psk(ct_tag: bytes, salt: bytes) -> bytes:
"""Get PSK password from user and decrypt Rx-PSK."""
while True:
try:
password = MasterKey.get_password("PSK password")
phase("Deriving the key decryption key", head=2)
kdk = argon2_kdf(password, salt, ARGON2_PSK_TIME_COST,
ARGON2_PSK_MEMORY_COST, ARGON2_PSK_PARALLELISM)
psk = auth_and_decrypt(ct_tag, kdk)
phase(DONE)
return psk
except nacl.exceptions.CryptoError:
print_on_previous_line()
m_print("Invalid password. Try again.", head=1)
print_on_previous_line(reps=5, delay=1)
except (EOFError, KeyboardInterrupt):
raise SoftError("PSK import aborted.",
head=2,
delay=1,
tail_clear=True)
def key_ex_psk_rx(packet: bytes, ts: 'datetime', window_list: 'WindowList',
contact_list: 'ContactList', key_list: 'KeyList',
settings: 'Settings') -> None:
"""Import Rx-PSK of contact."""
c_code, onion_pub_key = separate_header(packet, CONFIRM_CODE_LENGTH)
short_addr = pub_key_to_short_address(onion_pub_key)
if not contact_list.has_pub_key(onion_pub_key):
raise FunctionReturn(f"Error: Unknown account '{short_addr}'.",
head_clear=True)
contact = contact_list.get_contact_by_pub_key(onion_pub_key)
psk_file = ask_path_gui(f"Select PSK for {contact.nick} ({short_addr})",
settings,
get_file=True)
try:
with open(psk_file, 'rb') as f:
psk_data = f.read()
except PermissionError:
raise FunctionReturn("Error: No read permission for the PSK file.")
if len(psk_data) != PSK_FILE_SIZE:
raise FunctionReturn("Error: The PSK data in the file was invalid.",
head_clear=True)
salt, ct_tag = separate_header(psk_data, ARGON2_SALT_LENGTH)
while True:
try:
password = MasterKey.get_password("PSK password")
phase("Deriving the key decryption key", head=2)
kdk = argon2_kdf(password,
salt,
time_cost=ARGON2_PSK_TIME_COST,
memory_cost=ARGON2_PSK_MEMORY_COST)
psk = auth_and_decrypt(ct_tag, kdk)
phase(DONE)
break
except nacl.exceptions.CryptoError:
print_on_previous_line()
m_print("Invalid password. Try again.", head=1)
print_on_previous_line(reps=5, delay=1)
except (EOFError, KeyboardInterrupt):
raise FunctionReturn("PSK import aborted.",
head=2,
delay=1,
tail_clear=True)
rx_mk, rx_hk = separate_header(psk, SYMMETRIC_KEY_LENGTH)
if any(k == bytes(SYMMETRIC_KEY_LENGTH) for k in [rx_mk, rx_hk]):
raise FunctionReturn("Error: Received invalid keys from contact.",
head_clear=True)
keyset = key_list.get_keyset(onion_pub_key)
keyset.rx_mk = rx_mk
keyset.rx_hk = rx_hk
key_list.store_keys()
contact.kex_status = KEX_STATUS_HAS_RX_PSK
contact_list.store_contacts()
# Pipes protects against shell injection. Source of command's parameter is
# the program itself, and therefore trusted, but it's still good practice.
subprocess.Popen(f"shred -n 3 -z -u {pipes.quote(psk_file)}",
shell=True).wait()
if os.path.isfile(psk_file):
m_print(
f"Warning! Overwriting of PSK ({psk_file}) failed. Press <Enter> to continue.",
manual_proceed=True,
box=True)
message = f"Added Rx-side PSK for {contact.nick} ({short_addr})."
local_win = window_list.get_local_window()
local_win.add_new(ts, message)
m_print([
message, '', "Warning!",
"Physically destroy the keyfile transmission media ",
"to ensure it does not steal data from this computer!", '',
f"Confirmation code (to Transmitter): {c_code.hex()}"
],
box=True,
head=1,
tail=1)
def import_psk_rx_keys(cmd_data: bytes, ts: 'datetime',
window_list: 'WindowList', contact_list: 'ContactList',
key_list: 'KeyList', settings: 'Settings') -> None:
"""Import Rx-PSK of contact."""
account = cmd_data.decode()
if not contact_list.has_contact(account):
raise FunctionReturn(f"Error: Unknown account '{account}'")
contact = contact_list.get_contact(account)
psk_file = ask_path_gui(f"Select PSK for {contact.nick}",
settings,
get_file=True)
with open(psk_file, 'rb') as f:
psk_data = f.read()
if len(psk_data) != PSK_FILE_SIZE:
raise FunctionReturn("Error: Invalid PSK data in file.")
salt = psk_data[:ARGON2_SALT_LEN]
ct_tag = psk_data[ARGON2_SALT_LEN:]
while True:
try:
password = MasterKey.get_password("PSK password")
phase("Deriving key decryption key", head=2)
kdk, _ = argon2_kdf(password, salt, parallelism=1)
psk_pt = auth_and_decrypt(ct_tag, key=kdk, soft_e=True)
phase(DONE)
break
except nacl.exceptions.CryptoError:
print_on_previous_line()
c_print("Invalid password. Try again.", head=1)
print_on_previous_line(reps=5, delay=1.5)
except KeyboardInterrupt:
raise FunctionReturn("PSK import aborted.", head=2)
rx_key = psk_pt[0:32]
rx_hek = psk_pt[32:64]
if any(k == bytes(KEY_LENGTH) for k in [rx_key, rx_hek]):
raise FunctionReturn("Error: Received invalid keys from contact.")
keyset = key_list.get_keyset(account)
keyset.rx_key = rx_key
keyset.rx_hek = rx_hek
key_list.store_keys()
# Pipes protects against shell injection. Source of command's parameter
# is user's own RxM and therefore trusted, but it's still good practice.
subprocess.Popen(f"shred -n 3 -z -u {pipes.quote(psk_file)}",
shell=True).wait()
if os.path.isfile(psk_file):
box_print(
f"Warning! Overwriting of PSK ({psk_file}) failed. Press <Enter> to continue.",
manual_proceed=True)
local_win = window_list.get_local_window()
message = f"Added Rx-PSK for {contact.nick} ({account})."
local_win.add_new(ts, message)
box_print([
message, '', "Warning!",
"Physically destroy the keyfile transmission ",
"media to ensure that no data escapes RxM!"
],
head=1,
tail=1)
def psk_import(cmd_data: bytes, ts: 'datetime', window_list: 'WindowList',
contact_list: 'ContactList', key_list: 'KeyList',
settings: 'Settings') -> None:
"""Import rx-PSK of contact."""
account = cmd_data.decode()
if not contact_list.has_contact(account):
raise FunctionReturn(f"Unknown account {account}.")
contact = contact_list.get_contact(account)
pskf = ask_path_gui(f"Select PSK for {contact.nick}",
settings,
get_file=True)
with open(pskf, 'rb') as f:
psk_data = f.read()
if len(
psk_data
) != 136: # Nonce (24) + Salt (32) + rx-key (32) + rx-hek (32) + tag (16)
raise FunctionReturn("Invalid PSK data in file.")
salt = psk_data[:32]
ct_tag = psk_data[32:]
while True:
try:
password = MasterKey.get_password("PSK password")
phase("Deriving key decryption key", head=2)
kdk, _ = argon2_kdf(password,
salt,
rounds=16,
memory=128000,
parallelism=1)
psk_pt = auth_and_decrypt(ct_tag, key=kdk, soft_e=True)
phase("Done")
break
except nacl.exceptions.CryptoError:
print_on_previous_line()
c_print("Invalid password. Try again.", head=1)
print_on_previous_line(reps=5, delay=1.5)
except KeyboardInterrupt:
raise FunctionReturn("PSK import aborted.")
rx_key = psk_pt[0:32]
rx_hek = psk_pt[32:64]
if rx_key == bytes(32) or rx_hek == bytes(32):
raise FunctionReturn("Keys from contact are not valid.")
keyset = key_list.get_keyset(account)
keyset.rx_key = rx_key
keyset.rx_hek = rx_hek
key_list.store_keys()
# Pipes protects against shell injection. Source of command
# is trusted (user's own TxM) but it's still good practice.
subprocess.Popen("shred -n 3 -z -u {}".format(pipes.quote(pskf)),
shell=True).wait()
if os.path.isfile(pskf):
box_print(f"Warning! Overwriting of PSK ({pskf}) failed.")
time.sleep(3)
local_win = window_list.get_local_window()
local_win.print_new(ts,
f"Added Rx-PSK for {contact.nick} ({account})",
print_=False)
box_print([
f"Added Rx-PSK for {contact.nick}.", '', "Warning!",
"Physically destroy the keyfile transmission ",
"media to ensure that no data escapes RxM!"
],
head=1,
tail=1)
