"Fossies" - the Fresh Open Source Software Archive

Member "pyzor-1.0.0/pyzor/account.py" (10 Dec 2014, 2546 Bytes) of package /linux/privat/pyzor-1.0.0.tar.gz:

    1 """A collection of utilities that facilitate working with Pyzor accounts.
    2 
    3 Note that accounts are not necessary (on the client or server), as an
    4 "anonymous" account always exists."""
    5 
    6 import time
    7 import hashlib
    8 
    9 import pyzor
   10 
   11 
   12 def sign_msg(hashed_key, timestamp, msg, hash_=hashlib.sha1):
   13     """Converts the key, timestamp (epoch seconds), and msg into a digest.
   14 
   15     lower(H(H(M) + ':' T + ':' + K))
   16     M is message
   17     T is integer epoch timestamp
   18     K is hashed_key
   19     H is the hash function (currently SHA1)
   20     """
   21     msg = msg.as_string().strip().encode("utf8")
   22     digest = hash_()
   23     digest.update(hash_(msg).digest())
   24     digest.update((":%d:%s" % (timestamp, hashed_key)).encode("utf8"))
   25     return digest.hexdigest().lower()
   26 
   27 
   28 def hash_key(key, user, hash_=hashlib.sha1):
   29     """Returns the hash key for this username and password.
   30 
   31     lower(H(U + ':' + lower(K)))
   32     K is key (hex string)
   33     U is username
   34     H is the hash function (currently SHA1)
   35     """
   36     result = ("%s:%s" % (user, key.lower())).encode("utf8")
   37     return hash_(result).hexdigest().lower()
   38 
   39 
   40 def verify_signature(msg, user_key):
   41     """Verify that the provided message is correctly signed.
   42 
   43     The message must have "User", "Time", and "Sig" headers.
   44 
   45     If the signature is valid, then the function returns normally.
   46     If the signature is not valid, then a pyzor.SignatureError() exception
   47     is raised."""
   48     timestamp = int(msg["Time"])
   49     user = msg["User"]
   50     provided_signature = msg["Sig"]
   51     # Check that this signature is not too old.
   52     if abs(time.time() - timestamp) > pyzor.MAX_TIMESTAMP_DIFFERENCE:
   53         raise pyzor.SignatureError("Timestamp not within allowed range.")
   54     # Calculate what the correct signature is.
   55     hashed_user_key = hash_key(user_key, user)
   56     # The signature is not part of the message that is signed.
   57     del msg["Sig"]
   58     correct_signature = sign_msg(hashed_user_key, timestamp, msg)
   59     if correct_signature != provided_signature:
   60         raise pyzor.SignatureError("Invalid signature.")
   61 
   62 
   63 class Account(object):
   64     def __init__(self, username, salt, key):
   65         self.username = username
   66         self.salt = salt
   67         self.key = key
   68 
   69 
   70 def key_from_hexstr(s):
   71     try:
   72         salt, key = s.split(",")
   73     except ValueError:
   74         raise ValueError("Invalid number of parts for key; perhaps you "
   75                          "forgot the comma at the beginning for the "
   76                          "salt divider?")
   77     return salt, key
   78 
   79 AnonymousAccount = Account(pyzor.anonymous_user, None, "")