# Author: Trevor Perrin
# See the LICENSE file for legal information regarding use of this file.
"""Class for storing SRP password verifiers."""
from .utils.cryptomath import *
from .utils.compat import *
from tlslite import mathtls
from .basedb import BaseDB
[docs]
class VerifierDB(BaseDB):
"""This class represent an in-memory or on-disk database of SRP
password verifiers.
A VerifierDB can be passed to a server handshake to authenticate
a client based on one of the verifiers.
This class is thread-safe.
"""
[docs]
def __init__(self, filename=None):
"""Create a new VerifierDB instance.
:type filename: str
:param filename: Filename for an on-disk database, or None for
an in-memory database. If the filename already exists, follow
this with a call to open(). To create a new on-disk database,
follow this with a call to create().
"""
BaseDB.__init__(self, filename, b"verifier")
def _getItem(self, username, valueStr):
(N, g, salt, verifier) = valueStr.split(b" ")
N = bytesToNumber(a2b_base64(N))
g = bytesToNumber(a2b_base64(g))
salt = a2b_base64(salt)
verifier = bytesToNumber(a2b_base64(verifier))
return (N, g, salt, verifier)
[docs]
def __setitem__(self, username, verifierEntry):
"""Add a verifier entry to the database.
:type username: str
:param username: The username to associate the verifier with.
Must be less than 256 characters in length. Must not already
be in the database.
:type verifierEntry: tuple
:param verifierEntry: The verifier entry to add. Use
:py:meth:`~tlslite.verifierdb.VerifierDB.makeVerifier` to create a
verifier entry.
"""
BaseDB.__setitem__(self, username, verifierEntry)
def _setItem(self, username, value):
if len(username)>=256:
raise ValueError("username too long")
N, g, salt, verifier = value
N = b2a_base64(numberToByteArray(N)).encode("ascii")
g = b2a_base64(numberToByteArray(g)).encode("ascii")
salt = b2a_base64(salt).encode("ascii")
verifier = b2a_base64(numberToByteArray(verifier)).encode("ascii")
valueStr = b" ".join((N, g, salt, verifier))
return valueStr
def _checkItem(self, value, username, param):
(N, g, salt, verifier) = value
x = mathtls.makeX(salt, username, param)
v = powMod(g, x, N)
return (verifier == v)
[docs]
@staticmethod
def makeVerifier(username, password, bits):
"""Create a verifier entry which can be stored in a VerifierDB.
:type username: str
:param username: The username for this verifier. Must be less
than 256 characters in length.
:type password: str
:param password: The password for this verifier.
:type bits: int
:param bits: This values specifies which SRP group parameters
to use. It must be one of (1024, 1536, 2048, 3072, 4096, 6144,
8192). Larger values are more secure but slower. 2048 is a
good compromise between safety and speed.
:rtype: tuple
:returns: A tuple which may be stored in a VerifierDB.
"""
if isinstance(username, str):
usernameBytes = bytearray(username, "utf-8")
else:
usernameBytes = bytearray(username)
if isinstance(password, str):
passwordBytes = bytearray(password, "utf-8")
else:
passwordBytes = bytearray(password)
return mathtls.makeVerifier(usernameBytes, passwordBytes, bits)