1 # Author: Trevor Perrin
2 # See the LICENSE file for legal information regarding use of this file.
4 """Class for storing SRP password verifiers."""
6 from .utils.cryptomath import *
7 from .utils.compat import *
8 from tlslite import mathtls
9 from .basedb import BaseDB
11 class VerifierDB(BaseDB):
12 """This class represent an in-memory or on-disk database of SRP
15 A VerifierDB can be passed to a server handshake to authenticate
16 a client based on one of the verifiers.
18 This class is thread-safe.
20 def __init__(self, filename=None):
21 """Create a new VerifierDB instance.
24 @param filename: Filename for an on-disk database, or None for
25 an in-memory database. If the filename already exists, follow
26 this with a call to open(). To create a new on-disk database,
27 follow this with a call to create().
29 BaseDB.__init__(self, filename, "verifier")
31 def _getItem(self, username, valueStr):
32 (N, g, salt, verifier) = valueStr.split(" ")
33 N = bytesToNumber(a2b_base64(N))
34 g = bytesToNumber(a2b_base64(g))
35 salt = a2b_base64(salt)
36 verifier = bytesToNumber(a2b_base64(verifier))
37 return (N, g, salt, verifier)
39 def __setitem__(self, username, verifierEntry):
40 """Add a verifier entry to the database.
43 @param username: The username to associate the verifier with.
44 Must be less than 256 characters in length. Must not already
47 @type verifierEntry: tuple
48 @param verifierEntry: The verifier entry to add. Use
49 L{tlslite.verifierdb.VerifierDB.makeVerifier} to create a
52 BaseDB.__setitem__(self, username, verifierEntry)
55 def _setItem(self, username, value):
56 if len(username)>=256:
57 raise ValueError("username too long")
58 N, g, salt, verifier = value
59 N = b2a_base64(numberToByteArray(N))
60 g = b2a_base64(numberToByteArray(g))
61 salt = b2a_base64(salt)
62 verifier = b2a_base64(numberToByteArray(verifier))
63 valueStr = " ".join( (N, g, salt, verifier) )
66 def _checkItem(self, value, username, param):
67 (N, g, salt, verifier) = value
68 x = mathtls.makeX(salt, username, param)
70 return (verifier == v)
73 def makeVerifier(username, password, bits):
74 """Create a verifier entry which can be stored in a VerifierDB.
77 @param username: The username for this verifier. Must be less
78 than 256 characters in length.
81 @param password: The password for this verifier.
84 @param bits: This values specifies which SRP group parameters
85 to use. It must be one of (1024, 1536, 2048, 3072, 4096, 6144,
86 8192). Larger values are more secure but slower. 2048 is a
87 good compromise between safety and speed.
90 @return: A tuple which may be stored in a VerifierDB.
92 usernameBytes = bytearray(username, "utf-8")
93 passwordBytes = bytearray(password, "utf-8")
94 return mathtls.makeVerifier(usernameBytes, passwordBytes, bits)
95 makeVerifier = staticmethod(makeVerifier)