block_size = 1
iv_size = 0
def new(self, key, iv=None, initial_bytes=0):
"""Construct a new chacha20-poly1305 cipher object"""
# pylint: disable=no-self-use,unused-argument
return _Chacha20Poly1305Cipher(key)
try:
# pylint: disable=wrong-import-position,wrong-import-order
from libnacl import nacl
_CHACHA20_KEYBYTES = nacl.crypto_stream_chacha20_keybytes()
_CHACHA20_NONCEBYTES = nacl.crypto_stream_chacha20_noncebytes()
_chacha20 = nacl.crypto_stream_chacha20
_chacha20_xor_ic = nacl.crypto_stream_chacha20_xor_ic
_POLY1305_BYTES = nacl.crypto_onetimeauth_poly1305_bytes()
_POLY1305_KEYBYTES = nacl.crypto_onetimeauth_poly1305_keybytes()
_poly1305 = nacl.crypto_onetimeauth_poly1305
_poly1305_verify = nacl.crypto_onetimeauth_poly1305_verify
except (ImportError, OSError, AttributeError): # pragma: no cover
pass
else:
register_cipher('chacha20-poly1305', 'chacha', _Chacha20Poly1305Factory())
def verify_and_decrypt(self, header, data, nonce, tag):
if len(nonce) != _CHACHA20_NONCEBYTES:
raise ValueError('Invalid chacha20-poly1305 nonce size')
if self._verify_tag(header + data, nonce, tag):
plaintext = self._crypt(self._key, data, nonce, 1)
else:
plaintext = None
return plaintext
try:
from libnacl import nacl
_CHACHA20_KEYBYTES = nacl.crypto_stream_chacha20_keybytes()
_CHACHA20_NONCEBYTES = nacl.crypto_stream_chacha20_noncebytes()
_chacha20 = nacl.crypto_stream_chacha20
_chacha20_xor_ic = nacl.crypto_stream_chacha20_xor_ic
_POLY1305_BYTES = nacl.crypto_onetimeauth_poly1305_bytes()
_POLY1305_KEYBYTES = nacl.crypto_onetimeauth_poly1305_keybytes()
_poly1305 = nacl.crypto_onetimeauth_poly1305
_poly1305_verify = nacl.crypto_onetimeauth_poly1305_verify
except (ImportError, OSError, AttributeError):
pass
else:
register_cipher('chacha20-poly1305', 'chacha', _Chacha20Poly1305Cipher)