def __init__(self, privPEM = None, pubPEM = None, certPEM = None, force_tlsv1 = False):
priv = None
pub = None
cert = None
if privPEM and (pubPEM or certPEM):
priv = POW.pemRead(POW.RSA_PRIVATE_KEY, privPEM)
if pubPEM:
pub = POW.pemRead(POW.RSA_PUBLIC_KEY, pubPEM)
else:
rk = POW.Asymmetric(POW.RSA_CIPHER, 1536)
priv = POW.pemRead(POW.RSA_PRIVATE_KEY, rk.pemWrite(POW.RSA_PRIVATE_KEY))
pub = POW.pemRead(POW.RSA_PUBLIC_KEY, rk.pemWrite(POW.RSA_PUBLIC_KEY))
cert = None
if certPEM:
cert = POW.pemRead(POW.X509_CERTIFICATE, certPEM)
else:
name = [['CN', 'dropbox-client']]
cert = POW.X509()
cert.setVersion(3)
cert.setSerial(1)
cert.setSubject(name)
cert.setIssuer(name)
cert.setPublicKey(pub)
cert.setNotBefore(time2utc(0))
cert.setNotAfter(time2utc(time.time() + 31536000))
cert.sign(priv, POW.SHA256_DIGEST)
assert priv, 'Private Key was not set in core/p2p/crypto.py'
assert cert, 'Certificate was not set in core/p2p/crypto.py'
if not (privPEM and certPEM and not pubPEM):
assert pub, 'Public Key was not set in core/p2p/crypto.py'
self.cert = cert
self.priv = priv
self.pub = pub
self.force_tlsv1 = force_tlsv1
def readKeys(self):
"""Loads the 411 shared and master RSA keys"""
pub_file = open(self.pub_filename, 'r')
self.pub = POW.pemRead(POW.RSA_PUBLIC_KEY, pub_file.read())
pub_file.close()
shared_file = open(self.shared_filename, 'r')
self.shared = self.readSharedKey(shared_file.read())
shared_file.close()
if os.path.exists(self.priv_filename):
priv_file = open(self.priv_filename, 'r')
self.priv = POW.pemRead(POW.RSA_PRIVATE_KEY, priv_file.read())
priv_file.close()
def readKeys(self): """Loads the 411 shared and master RSA keys""" pub_file = open(self.pub_filename, 'r') self.pub = POW.pemRead(POW.RSA_PUBLIC_KEY, pub_file.read()) pub_file.close() shared_file = open(self.shared_filename, 'r') self.shared = self.readSharedKey(shared_file.read()) shared_file.close() if os.path.exists(self.priv_filename): priv_file = open(self.priv_filename, 'r') self.priv = POW.pemRead(POW.RSA_PRIVATE_KEY, priv_file.read()) priv_file.close()
def generateSessionKeyV1(password, lmhash, nthash):
if POW:
hash = POW.Digest(POW.MD4_DIGEST)
else:
hash = MD4.new()
hash.update(NTOWFv1(password, lmhash, nthash))
return hash.digest()
def __DES_block(key, msg):
if POW:
cipher = POW.Symmetric(POW.DES_ECB)
cipher.encryptInit(__expand_DES_key(key))
return cipher.update(msg)
else:
cipher = DES.new(__expand_DES_key(key), DES.MODE_ECB)
return cipher.encrypt(msg)
def generate_session_key(self):
bytes = self.get_random_bytes(32)
_k = POW.rsaFromBN(self.K[0], self.K[1])
log_key = md5(bytes).digest()
header = _k.publicEncrypt(log_key)
with self._klock:
self.header = header
self.log_key = log_key
def compute_nthash(password):
# This is done according to Samba's encryption specification (docs/html/ENCRYPTION.html)
password = unicode(password).encode('utf_16le')
if POW:
hash = POW.Digest(POW.MD4_DIGEST)
else:
hash = MD4.new()
hash.update(password)
return hash.digest()
def hmac_md5(key, data):
if POW:
h = POW.Hmac(POW.MD5_DIGEST, key)
h.update(data)
result = h.mac()
else:
import hmac
h = hmac.new(key)
h.update(data)
result = h.digest()
return result
def generateEncryptedSessionKey(keyExchangeKey, exportedSessionKey):
if POW:
cipher = POW.Symmetric(POW.RC4)
cipher.encryptInit(keyExchangeKey)
cipher_encrypt = cipher.update
else:
cipher = ARC4.new(keyExchangeKey)
cipher_encrypt = cipher.encrypt
sessionKey = cipher_encrypt(exportedSessionKey)
return sessionKey
def sign(self, plaintext):
"""Sign the message with our private key. Returns the
base64 encoded signature."""
if not self.priv: self.readKeys()
digest = POW.Digest(POW.MD5_DIGEST)
digest.update(plaintext)
return base64.encodestring(
self.priv.sign(digest.digest(), POW.MD5_DIGEST))
def write_host_dbx(host_int, dropbox_location, appdata_path):
try:
_k = POW.rsaFromBN(DropboxLog.K[0], DropboxLog.K[1])
enc_host_int = base64.b64encode(_k.publicEncrypt(str(host_int)))
assert len(enc_host_int) == 172
lines = [enc_host_int, base64.b64encode(dropbox_location.encode('utf8'))]
host_db_path = os.path.join(appdata_path, _HOSTDBX_NAME)
with open(host_db_path, 'wb') as f:
f.write('\n'.join(lines))
except Exception:
unhandled_exc_handler()
def compute_nthash(password):
# This is done according to Samba's encryption specification (docs/html/ENCRYPTION.html)
try:
password = unicode(password).encode('utf_16le')
except UnicodeDecodeError:
import sys
password = password.decode(sys.getfilesystemencoding()).encode('utf_16le')
if POW:
hash = POW.Digest(POW.MD4_DIGEST)
else:
hash = MD4.new()
hash.update(password)
return hash.digest()
def verify_signature(info):
pub_key = POW.pemRead(POW.RSA_PUBLIC_KEY, PUBLICKEY)
d = info['digest'].digest()
signed = False
for sig in info['sigs']:
try:
pub_key.verify(sig, d, POW.SHA256_DIGEST)
signed = True
break
except Exception as e:
error = e
if signed:
return True
raise error
def __init__(self):
self.priv_filename = '/etc/411-security/master.key'
self.pub_filename = '/etc/411-security/master.pub'
self.shared_filename = '/etc/411-security/shared.key'
self.masters = []
# Our current favorite
self.master = None
self.disable = 0
self.verbose = 0
# The directory from which we place our 411 files. Used
# when translating 411 file paths.
self.rootdir = "/"
self.sym = None
self.pool = None
# Master keys
self.priv = None
self.pub = None
# Shared key, 256bit + 64bit IV
self.shared = None
self.conn = None
# Default URL base path to find files.
self.urldir = '411.d'
# Groups we are interested in
self.groups = ['']
# Store attributes which we can use to filter on.
self.attrs = {}
self.config = Conf(self)
self.config.parse()
self.plugin = None
# A regex for our header search.
pattern = "\n*(?P<comment>.*?)\$411id\$"
self.header_pattern = re.compile(pattern)
pattern = "<a href=.+>(?P<filename>.+)</a> +(?P<date>\d+.*) +(?P<size>\d+.*)"
# Make the pattern matching engine case-insensitive.
self.dir_pattern = re.compile(pattern, re.I)
# Use Blowfish with fast Cipher Block Chaining.
self.sym = POW.Symmetric(POW.BF_CBC)
#Embedded file name: dropbox/sync_engine/p2p/crypto.py
from __future__ import absolute_import
import time
import POW
from dropbox.trace import TRACE, unhandled_exc_handler
dhParams_data = '\n-----BEGIN DH PARAMETERS-----\nMIHHAoHBAK7J14riM20k2t9Ahup6rjr70ST8HgVhR+4hm908rgBpB5GIhlbrIAS2\nNdLsXcwpnYvf3xiT0zHQyITVv8/9pKCjR2pkkdpRCse72StyLpOq9DGB6oVc+Jst\npiU0hROT+if77uMe9IYlhozfubkbsAAPvRUtElT5IP4GRyYh1rMxqnvD3HeEBePE\n5A0Xg4aKJeuVFaYDjSpm+zuAlXlT5M4mC5dlu6MULUZUOxtimmxk2eWGkYa44zB3\nV7J9o/EZ+wIBAg==\n-----END DH PARAMETERS-----\n'
dhParams = POW.pemRead(POW.DH_PARAMS, dhParams_data)
def time2utc(val):
return time.strftime('%y%m%d%H%M%SZ', time.gmtime(int(val)))
class CryptoData(object):
def __init__(self, privPEM = None, pubPEM = None, certPEM = None, force_tlsv1 = False):
priv = None
pub = None
cert = None
if privPEM and (pubPEM or certPEM):
priv = POW.pemRead(POW.RSA_PRIVATE_KEY, privPEM)
if pubPEM:
pub = POW.pemRead(POW.RSA_PUBLIC_KEY, pubPEM)
else:
rk = POW.Asymmetric(POW.RSA_CIPHER, 1536)
priv = POW.pemRead(POW.RSA_PRIVATE_KEY, rk.pemWrite(POW.RSA_PRIVATE_KEY))
pub = POW.pemRead(POW.RSA_PUBLIC_KEY, rk.pemWrite(POW.RSA_PUBLIC_KEY))
cert = None
if certPEM:
cert = POW.pemRead(POW.X509_CERTIFICATE, certPEM)
else:
name = [['CN', 'dropbox-client']]
def bind(self, uuid, alter=0, bogus_binds=0):
bind = MSRPCBind(endianness=self.endianness)
syntax = '\x04\x5d\x88\x8a\xeb\x1c\xc9\x11\x9f\xe8\x08\x00\x2b\x10\x48\x60'
if self.endianness == '>':
syntax = unpack('<LHHBB6s', syntax)
syntax = pack('>LHHBB6s', *syntax)
uuid = list(unpack('<LHHBB6sHH', uuid))
uuid[-1] ^= uuid[-2]
uuid[-2] ^= uuid[-1]
uuid[-1] ^= uuid[-2]
uuid = pack('>LHHBB6sHH', *uuid)
ctx = 0
for i in range(bogus_binds):
bind.set_ctx_id(self._ctx, index=ctx)
bind.set_trans_num(1, index=ctx)
bind.set_if_binuuid('A' * 20, index=ctx)
bind.set_xfer_syntax_binuuid(syntax, index=ctx)
bind.set_xfer_syntax_ver(2, index=ctx)
self._ctx += 1
ctx += 1
bind.set_ctx_id(self._ctx, index=ctx)
bind.set_trans_num(1, index=ctx)
bind.set_if_binuuid(uuid, index=ctx)
bind.set_xfer_syntax_binuuid(syntax, index=ctx)
bind.set_xfer_syntax_ver(2, index=ctx)
bind.set_ctx_num(ctx + 1)
if alter:
bind.set_type(MSRPC_ALTERCTX)
if (self.__auth_level != ntlm.NTLM_AUTH_NONE):
if (self.__username is None) or (self.__password is None):
self.__username, self.__password, nth, lmh = self._transport.get_credentials(
)
auth = ntlm.NTLMAuthNegotiate()
auth['auth_level'] = self.__auth_level
auth['auth_ctx_id'] = self._ctx + 79231
bind.set_auth_data(str(auth))
self._transport.send(bind.get_packet())
s = self._transport.recv()
if s != 0:
resp = MSRPCBindAck(s)
else:
return 0 #mmm why not None?
if resp.get_type() == MSRPC_BINDNAK:
resp = MSRPCBindNak(s)
status_code = resp.get_reason()
if rpc_status_codes.has_key(status_code):
raise Exception(rpc_status_codes[status_code], resp)
else:
raise Exception(
'Unknown DCE RPC fault status code: %.8x' % status_code,
resp)
self.__max_xmit_size = resp.get_max_tfrag()
if self.__auth_level != ntlm.NTLM_AUTH_NONE:
authResp = ntlm.NTLMAuthChallenge(
data=resp.get_auth_data().tostring())
self._ntlm_challenge = authResp['challenge']
response = ntlm.NTLMAuthChallengeResponse(self.__username,
self.__password,
self._ntlm_challenge)
response['auth_ctx_id'] = self._ctx + 79231
response['auth_level'] = self.__auth_level
if self.__auth_level in (ntlm.NTLM_AUTH_CONNECT,
ntlm.NTLM_AUTH_PKT_INTEGRITY,
ntlm.NTLM_AUTH_PKT_PRIVACY):
if self.__password:
key = ntlm.compute_nthash(self.__password)
if POW:
hash = POW.Digest(POW.MD4_DIGEST)
else:
hash = MD4.new()
hash.update(key)
key = hash.digest()
else:
key = '\x00' * 16
if POW:
cipher = POW.Symmetric(POW.RC4)
cipher.encryptInit(key)
self.cipher_encrypt = cipher.update
else:
cipher = ARC4.new(key)
self.cipher_encrypt = cipher.encrypt
if response['flags'] & ntlm.NTLMSSP_KEY_EXCHANGE:
session_key = 'A' * 16 # XXX Generate random session key
response['session_key'] = self.cipher_encrypt(session_key)
if POW:
cipher = POW.Symmetric(POW.RC4)
cipher.encryptInit(session_key)
self.cipher_encrypt = cipher.update
else:
cipher = ARC4.new(session_key)
self.cipher_encrypt = cipher.encrypt
self.sequence = 0
auth3 = MSRPCHeader()
auth3.set_type(MSRPC_AUTH3)
auth3.set_auth_data(str(response))
self._transport.send(auth3.get_packet(), forceWriteAndx=1)
return resp # means packet is signed, if verifier is wrong it fails
['ST', 'Victoria'],
['O', 'eigenmagic'],
['CU', 'Justin Warren'],
]
if powmode:
import POW
import POW.pkix
import time
passphrase = 'TeSt'
md5 = POW.Digest( POW.MD5_DIGEST )
md5.update( passphrase )
password = md5.digest()
publicKey = POW.pemRead(POW.RSA_PUBLIC_KEY, publicFile.read())
privateKey = POW.pemRead(POW.RSA_PRIVATE_KEY, privateFile.read(), password)
c = POW.X509()
#c.setIssuer( name )
#c.setSubject( name )
c.setSerial(0)
# Expiry information
t1 = POW.pkix.time2utc( time.time() )
t2 = POW.pkix.time2utc( time.time() + 60*60*24*365 )
c.setNotBefore(t1)
c.setNotAfter(t2)
c.setPublicKey(publicKey)
class Service411:
"""Can retrieve a 411 file from a set of master servers. Has the
ability to encrypt, and decrypt files using a hybrid RSA-Symmetric
cryptographic technique. Only as safe as your sysadmin."""
def __init__(self):
self.priv_filename = '/etc/411-security/master.key'
self.pub_filename = '/etc/411-security/master.pub'
self.shared_filename = '/etc/411-security/shared.key'
self.masters = []
# Our current favorite
self.master = None
self.disable = 0
self.verbose = 0
# The directory from which we place our 411 files. Used
# when translating 411 file paths.
self.rootdir = "/"
self.sym = None
self.pool = None
# Master keys
self.priv = None
self.pub = None
# Shared key, 256bit + 64bit IV
self.shared = None
self.conn = None
# Default URL base path to find files.
self.urldir = '411.d'
# Groups we are interested in
self.groups = ['']
# Store attributes which we can use to filter on.
self.attrs = {}
self.config = Conf(self)
self.config.parse()
self.plugin = None
# A regex for our header search.
pattern = "\n*(?P<comment>.*?)\$411id\$"
self.header_pattern = re.compile(pattern)
pattern = "<a href=.+>(?P<filename>.+)</a> +(?P<date>\d+.*) +(?P<size>\d+.*)"
# Make the pattern matching engine case-insensitive.
self.dir_pattern = re.compile(pattern, re.I)
# Use Blowfish with fast Cipher Block Chaining.
self.sym = POW.Symmetric(POW.BF_CBC)
def fillPool(self):
"""Starts the random pool. Dont do in constructor since this
is computationally intensive."""
# A cryptographically safe source of random data.
self.pool = RandomPool(384)
def setConf(self, conf):
self.config = conf(self)
def setConfHandler(self, handler):
self.config.setHandler(handler)
self.config.parse()
def four11Path(self, filename411):
"""Translates 411 file names into UNIX absolute filenames."""
# Warning this is UNIX dependant
n = string.replace(filename411, ".", "/")
n = string.replace(n, "//", ".")
return os.path.normpath(os.path.join(self.rootdir, n))
def path411(self, filename):
"""Turns an absolute UNIX path into a 411 filename. Every
period ('.') is a filesystem delimeter (like /), and all
filenames are assumed to be absolute, to start with a /. A
literal period is coded as a double period ('..'). """
# Warning, this is UNIX dependant.
n = string.replace(filename[1:], ".", "..")
n = string.replace(n, "/", ".")
return n
def connect(self, master=None):
"""Opens a HTTP 1.1 connection to the first live master server.
Will use the master argument if specified, otherwise consults
internal master server list. This connection can service
multiple requests."""
if self.conn:
self.disconnect()
if master:
masters = [master]
else:
masters = self.getMasters()
if not masters:
raise ValueError, \
"We have no master servers to connect to."
conn = None
for master in masters:
# Split address into host & port
m = master.getAddress().split(':')
if len(m) == 2:
conn = HTTPConnection(m[0], int(m[1]))
else:
conn = HTTPConnection(m[0])
# Test the connection.
try:
# Set variable so that connection originates
# from privileged port only. This way, only
# root can initialize this connection
conn.privileged_port = True
conn.connect()
except:
# If we cannot connect, devalue this server.
master.decScore()
conn = None
continue
else:
# We pick the first master that accepts a
# connection.
self.master = master
master.incScore()
break
if conn:
self.conn = conn
else:
raise Error411, \
"Could not reach a master server. Masters: %s" \
% masters
def disconnect(self):
"""Closes the master HTTP connection. """
if self.conn:
self.conn.close()
self.conn = None
def get(self, file):
""" Retrives a 411 file. If arg is empty, a directory listing
dictionary is returned. If file is valid, returns the decrypted
contents and its associated meta data. """
if not file:
raise Error411, "I need a file to get"
# Allow you to get a full URL.
if file.count("http://"):
m = Master(file)
self.connect(m)
file = os.path.basename(file)
else:
# We use our internal configuration.
self.connect()
path = self.master.getDir() + file
self.conn.request('GET', urllib.quote(path))
headers = self.conn.getresponse()
status = headers['status']
reason = headers['reason']
if status != 200:
raise Error411, "Could not get file '%s%s': %s %s" % \
(self.master.getUrl(), file, status, reason)
contents = self.conn.read()
self.disconnect()
if file[-1] == '/': # A directory
return contents
else:
return self.decrypt(contents)
def find(self, path="/"):
"""Finds all relevant files to retrieve on a master server.
Returns dict indexed by file path containing mtime and size."""
self.files = {}
self.findHelper(path)
return self.files
def findHelper(self, path, depth=0):
listing = self.get(path)
lines = listing.split("\n")
for line in lines:
m = self.dir_pattern.search(line)
if not m:
continue
#print line
filename = m.group('filename')
if filename == "Parent Directory":
continue
if filename[-1] == '/':
if self.verbose:
print "Found directory %s (%s)" \
% (path+filename, depth)
if self.isInteresting(path + filename, depth):
self.findHelper(path + filename, depth + 1)
continue
date = m.group('date').strip()
size = m.group('size').strip()
self.files[path + filename] = {
"Name": filename,
"Modified": date,
"Size": size
}
def isInteresting(self, path, level):
"""Matches an offered group our registered groups. Slow,
search time is squared with the number of registered groups.
"""
offered = path[1:-1].split('/')
elements = len(offered)
for r in self.groups:
if not r:
continue
if self.verbose:
print "Matching %s to %s level %s" \
% (offered, r[:len(offered)], level)
try:
# Shorten the registered group to match
# the offerred one, then compare. Allows
# group inheritance.
if offered == r[:len(offered)]:
return 1
except:
continue
return 0
def readKeys(self):
"""Loads the 411 shared and master RSA keys"""
pub_file = open(self.pub_filename, 'r')
self.pub = POW.pemRead(POW.RSA_PUBLIC_KEY, pub_file.read())
pub_file.close()
shared_file = open(self.shared_filename, 'r')
self.shared = self.readSharedKey(shared_file.read())
shared_file.close()
if os.path.exists(self.priv_filename):
priv_file = open(self.priv_filename, 'r')
self.priv = POW.pemRead(POW.RSA_PRIVATE_KEY, priv_file.read())
priv_file.close()
def makeSharedKey(self):
"""Uses our cryptographically safe random number generator to
give us a 256bit session key and 64bit Init Vector, in 411 format."""
if not self.pool:
self.fillPool()
while 1:
self.pool.stir()
randomkey = self.pool.get_bytes(40)
# First 256 bits are for the session key
sessionkey = randomkey[:32]
# Last 64 bits are for the CBC initial value.
initialvalue = randomkey[-8:]
try:
self.sym.encryptInit(sessionkey, initialvalue)
except TypeError:
# Need a new session key (null chars in our key)
continue
else:
break
key = "-----BEGIN 411 SHARED KEY-----\n"
key += base64.encodestring(randomkey)
key += "-----END 411 SHARED KEY-----\n"
return key
def readSharedKey(self, key64):
"""Read a 411 shared key in base64 encoding and return the
binary bits"""
header = "-----BEGIN 411 SHARED KEY-----\n"
footer = "-----END 411 SHARED KEY-----\n"
try:
a = key64.index(header) + len(header)
b = key64.index(footer)
key = base64.decodestring(key64[a:b])
except:
raise Error411, \
"This does not appear to be a 411 shared key."
return key
def encrypt(self,
plaintext,
header="-----BEGIN 411 MESSAGE-----\n",
footer="-----END 411 MESSAGE-----\n",
sign=1):
"""Encrypts the plain text message using a hybrid cryptography
technique: a 256-bit random session key is encrypted with the
cluster shared key. The session key is used to quickly encrypt
the message with the Blowfish symmetrical algorithm."""
if not self.shared:
self.readKeys()
# First 256 bits are for the session key,
# Last 64 bits are for the CBC initial value.
try:
self.sym.encryptInit(self.shared[:32], self.shared[-8:])
except TypeError:
raise Error411, "Invalid Shared Key"
# Sign the text with the master private key
if sign:
if not self.priv:
raise Error411, "I need the master private key to sign messages"
sig = self.sign(plaintext)
else:
sig = "Not Signed"
# Encrypt the text with Blowfish for speed.
ciphertext = self.sym.update(plaintext) + self.sym.final()
ciphertext_base64 = base64.encodestring(ciphertext)
# Message format (v2.0):
# digital signature
# <blank line>
# symmetrically-encrypted message
msg = header
msg += sig + "\n"
msg += ciphertext_base64
msg += footer
return msg
def decrypt(self,
contents,
header="-----BEGIN 411 MESSAGE-----\n",
footer="-----END 411 MESSAGE-----\n",
type411=1):
"""Uses the shared key to read 411 messages. For 411
type messages, returns the tuple (contents, meta) where meta is
a dictionary containing the 411 headers. If not type 411,
returns a (plaintext, sig_base64). No verification of signature
is performed."""
if not self.sym:
self.fillPool()
ciphersig_base64 = ''
try:
a = string.index(contents, header) + len(header)
b = string.index(contents, footer)
msg = contents[a:b]
ciphersig_base64, ciphertext_base64 = msg.split('\n\n')
ciphertext = base64.decodestring(ciphertext_base64)
except:
raise Error411, \
"This file does not appear to be in 411 format."
if not self.shared:
self.readKeys()
sessionkey = self.shared[:32]
initialvalue = self.shared[-8:]
self.sym.decryptInit(sessionkey, initialvalue)
try:
text = self.sym.update(ciphertext) + self.sym.final()
except POW.SSLError:
raise Error411, "Could not decrypt file, wrong key?"
if type411:
if not self.verify(text, ciphersig_base64):
raise Error411, "Signature does not verify."
return self.decode(text)
else:
return (text, ciphersig_base64)
def decode(self, plaintext):
meta = {}
p = Parser(plaintext, self.attrs)
meta = p.get_filtered_content()
self.plugin = p.get_plugin()
return meta['content'], meta
def verify(self, msg, sig_base64):
"""Verifies that the plaintext message was signed with the
(base64 encoded) signature, and has not been altered since
signing. Returns true if message verifies."""
if not self.pub:
try:
self.readKeys()
except IOError, e:
syslog.syslog(syslog.LOG_ERR, '411-error: ' \
+ str(e))
return 0
digest = POW.Digest(POW.MD5_DIGEST)
digest.update(msg)
try:
sig = base64.decodestring(sig_base64)
except:
return 0
return self.pub.verify(sig, digest.digest(), POW.MD5_DIGEST)
def generate_session_key(self):
bytes = self.get_random_bytes(32)
_k = POW.rsaFromBN(DropboxLog.K[0], DropboxLog.K[1])
self.log_key = md5(bytes).digest()
self.header = _k.publicEncrypt(self.log_key)
self.iv = md5(self.log_key).digest()[:16]
