PyBitmessage/src/protocol.py

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# pylint: disable=too-many-boolean-expressions,too-many-return-statements,too-many-locals,too-many-statements
"""
protocol.py
===========
Low-level protocol-related functions.
"""
from __future__ import absolute_import
import base64
from binascii import hexlify
import hashlib
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import os
import random
import socket
import ssl
from struct import pack, unpack, Struct
import sys
import time
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import traceback
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import defaults
import highlevelcrypto
import state
from addresses import encodeVarint, decodeVarint, decodeAddress, varintDecodeError
from bmconfigparser import BMConfigParser
from debug import logger
from helper_sql import sqlExecute
from version import softwareVersion
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# Service flags
NODE_NETWORK = 1
NODE_SSL = 2
NODE_DANDELION = 8
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# Bitfield flags
BITFIELD_DOESACK = 1
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# Error types
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STATUS_WARNING = 0
STATUS_ERROR = 1
STATUS_FATAL = 2
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# Object types
OBJECT_GETPUBKEY = 0
OBJECT_PUBKEY = 1
OBJECT_MSG = 2
OBJECT_BROADCAST = 3
OBJECT_I2P = 0x493250
OBJECT_ADDR = 0x61646472
eightBytesOfRandomDataUsedToDetectConnectionsToSelf = pack(
'>Q', random.randrange(1, 18446744073709551615))
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# Compiled struct for packing/unpacking headers
# New code should use CreatePacket instead of Header.pack
Header = Struct('!L12sL4s')
VersionPacket = Struct('>LqQ20s4s36sH')
# Bitfield
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def getBitfield(address):
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"""Get a bitfield from an address"""
# bitfield of features supported by me (see the wiki).
bitfield = 0
# send ack
if not BMConfigParser().safeGetBoolean(address, 'dontsendack'):
bitfield |= BITFIELD_DOESACK
return pack('>I', bitfield)
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def checkBitfield(bitfieldBinary, flags):
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"""Check if a bitfield matches the given flags"""
bitfield, = unpack('>I', bitfieldBinary)
return (bitfield & flags) == flags
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def isBitSetWithinBitfield(fourByteString, n):
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"""Check if a particular bit is set in a bitfeld"""
# Uses MSB 0 bit numbering across 4 bytes of data
n = 31 - n
x, = unpack('>L', fourByteString)
return x & 2**n != 0
# ip addresses
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def encodeHost(host):
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"""Encode a given host to be used in low-level socket operations"""
if host.find('.onion') > -1:
return '\xfd\x87\xd8\x7e\xeb\x43' + base64.b32decode(host.split(".")[0], True)
elif host.find(':') == -1:
return '\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xFF\xFF' + \
socket.inet_aton(host)
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return socket.inet_pton(socket.AF_INET6, host)
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def networkType(host):
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"""Determine if a host is IPv4, IPv6 or an onion address"""
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if host.find('.onion') > -1:
return 'onion'
elif host.find(':') == -1:
return 'IPv4'
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return 'IPv6'
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def checkIPAddress(host, private=False):
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"""Returns hostStandardFormat if it is a valid IP address, otherwise returns False"""
if host[0:12] == '\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xFF\xFF':
hostStandardFormat = socket.inet_ntop(socket.AF_INET, host[12:])
return checkIPv4Address(host[12:], hostStandardFormat, private)
elif host[0:6] == '\xfd\x87\xd8\x7e\xeb\x43':
# Onion, based on BMD/bitcoind
hostStandardFormat = base64.b32encode(host[6:]).lower() + ".onion"
if private:
return False
return hostStandardFormat
else:
try:
hostStandardFormat = socket.inet_ntop(socket.AF_INET6, host)
except ValueError:
return False
if hostStandardFormat == "":
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# This can happen on Windows systems which are not 64-bit compatible
# so let us drop the IPv6 address.
return False
return checkIPv6Address(host, hostStandardFormat, private)
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def checkIPv4Address(host, hostStandardFormat, private=False):
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"""Returns hostStandardFormat if it is an IPv4 address, otherwise returns False"""
if host[0] == '\x7F': # 127/8
if not private:
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logger.debug('Ignoring IP address in loopback range: %s', hostStandardFormat)
return hostStandardFormat if private else False
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if host[0] == '\x0A': # 10/8
if not private:
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logger.debug('Ignoring IP address in private range: %s', hostStandardFormat)
return hostStandardFormat if private else False
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if host[0:2] == '\xC0\xA8': # 192.168/16
if not private:
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logger.debug('Ignoring IP address in private range: %s', hostStandardFormat)
return hostStandardFormat if private else False
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if host[0:2] >= '\xAC\x10' and host[0:2] < '\xAC\x20': # 172.16/12
if not private:
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logger.debug('Ignoring IP address in private range: %s', hostStandardFormat)
return hostStandardFormat if private else False
return False if private else hostStandardFormat
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def checkIPv6Address(host, hostStandardFormat, private=False):
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"""Returns hostStandardFormat if it is an IPv6 address, otherwise returns False"""
if host == ('\x00' * 15) + '\x01':
if not private:
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logger.debug('Ignoring loopback address: %s', hostStandardFormat)
return False
if host[0] == '\xFE' and (ord(host[1]) & 0xc0) == 0x80:
if not private:
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logger.debug('Ignoring local address: %s', hostStandardFormat)
return hostStandardFormat if private else False
if (ord(host[0]) & 0xfe) == 0xfc:
if not private:
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logger.debug('Ignoring unique local address: %s', hostStandardFormat)
return hostStandardFormat if private else False
return False if private else hostStandardFormat
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def haveSSL(server=False):
"""
Predicate to check if ECDSA server support is required and available
python < 2.7.9's ssl library does not support ECDSA server due to
missing initialisation of available curves, but client works ok
"""
if not server:
return True
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elif sys.version_info >= (2, 7, 9):
return True
return False
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def checkSocksIP(host):
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"""Predicate to check if we're using a SOCKS proxy"""
try:
if state.socksIP is None or not state.socksIP:
state.socksIP = socket.gethostbyname(BMConfigParser().get("bitmessagesettings", "sockshostname"))
# uninitialised
except NameError:
state.socksIP = socket.gethostbyname(BMConfigParser().get("bitmessagesettings", "sockshostname"))
# resolving failure
except socket.gaierror:
state.socksIP = BMConfigParser().get("bitmessagesettings", "sockshostname")
return state.socksIP == host
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def isProofOfWorkSufficient(data,
nonceTrialsPerByte=0,
payloadLengthExtraBytes=0,
recvTime=0):
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"""
Validate an object's Proof of Work using method described in:
https://bitmessage.org/wiki/Proof_of_work
Arguments:
int nonceTrialsPerByte (default: from default.py)
int payloadLengthExtraBytes (default: from default.py)
float recvTime (optional) UNIX epoch time when object was
received from the network (default: current system time)
Returns:
True if PoW valid and sufficient, False in all other cases
"""
if nonceTrialsPerByte < defaults.networkDefaultProofOfWorkNonceTrialsPerByte:
nonceTrialsPerByte = defaults.networkDefaultProofOfWorkNonceTrialsPerByte
if payloadLengthExtraBytes < defaults.networkDefaultPayloadLengthExtraBytes:
payloadLengthExtraBytes = defaults.networkDefaultPayloadLengthExtraBytes
endOfLifeTime, = unpack('>Q', data[8:16])
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TTL = endOfLifeTime - (int(recvTime) if recvTime else int(time.time()))
if TTL < 300:
TTL = 300
POW, = unpack('>Q', hashlib.sha512(hashlib.sha512(data[
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:8] + hashlib.sha512(data[8:]).digest()).digest()).digest()[0:8])
return POW <= 2 ** 64 / (nonceTrialsPerByte *
(len(data) + payloadLengthExtraBytes +
((TTL * (len(data) + payloadLengthExtraBytes)) / (2 ** 16))))
# Packet creation
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def CreatePacket(command, payload=''):
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"""Construct and return a number of bytes from a payload"""
payload_length = len(payload)
checksum = hashlib.sha512(payload).digest()[0:4]
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b = bytearray(Header.size + payload_length)
Header.pack_into(b, 0, 0xE9BEB4D9, command, payload_length, checksum)
b[Header.size:] = payload
return bytes(b)
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def assembleVersionMessage(remoteHost, remotePort, participatingStreams, server=False, nodeid=None):
"""Construct the payload of a version message, return the resultng bytes of running CreatePacket() on it"""
payload = ''
payload += pack('>L', 3) # protocol version.
# bitflags of the services I offer.
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payload += pack(
'>q',
NODE_NETWORK |
(NODE_SSL if haveSSL(server) else 0) |
(NODE_DANDELION if state.dandelion else 0)
)
payload += pack('>q', int(time.time()))
payload += pack(
'>q', 1) # boolservices of remote connection; ignored by the remote host.
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if checkSocksIP(remoteHost) and server: # prevent leaking of tor outbound IP
payload += encodeHost('127.0.0.1')
payload += pack('>H', 8444)
else:
payload += encodeHost(remoteHost)
payload += pack('>H', remotePort) # remote IPv6 and port
# bitflags of the services I offer.
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payload += pack(
'>q',
NODE_NETWORK |
(NODE_SSL if haveSSL(server) else 0) |
(NODE_DANDELION if state.dandelion else 0)
)
# = 127.0.0.1. This will be ignored by the remote host. The actual remote connected IP will be used.
payload += '\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xFF\xFF' + pack('>L', 2130706433)
# we have a separate extPort and incoming over clearnet or outgoing through clearnet
if BMConfigParser().safeGetBoolean('bitmessagesettings', 'upnp') and state.extPort \
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and ((server and not checkSocksIP(remoteHost)) or
(BMConfigParser().get("bitmessagesettings", "socksproxytype") == "none" and not server)):
payload += pack('>H', state.extPort)
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elif checkSocksIP(remoteHost) and server: # incoming connection over Tor
payload += pack('>H', BMConfigParser().getint('bitmessagesettings', 'onionport'))
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else: # no extPort and not incoming over Tor
payload += pack('>H', BMConfigParser().getint('bitmessagesettings', 'port'))
random.seed()
if nodeid is not None:
payload += nodeid[0:8]
else:
payload += eightBytesOfRandomDataUsedToDetectConnectionsToSelf
userAgent = '/PyBitmessage:' + softwareVersion + '/'
payload += encodeVarint(len(userAgent))
payload += userAgent
# Streams
payload += encodeVarint(len(participatingStreams))
count = 0
for stream in sorted(participatingStreams):
payload += encodeVarint(stream)
count += 1
# protocol limit, see specification
if count >= 160000:
break
return CreatePacket('version', payload)
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def assembleErrorMessage(fatal=0, banTime=0, inventoryVector='', errorText=''):
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"""Construct the payload of an error message, return the resultng bytes of running CreatePacket() on it"""
payload = encodeVarint(fatal)
payload += encodeVarint(banTime)
payload += encodeVarint(len(inventoryVector))
payload += inventoryVector
payload += encodeVarint(len(errorText))
payload += errorText
return CreatePacket('error', payload)
# Packet decoding
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def decryptAndCheckPubkeyPayload(data, address):
"""
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Version 4 pubkeys are encrypted. This function is run when we already have the
address to which we want to try to send a message. The 'data' may come either
off of the wire or we might have had it already in our inventory when we tried
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to send a msg to this particular address.
"""
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# pylint: disable=unused-variable
try:
status, addressVersion, streamNumber, ripe = decodeAddress(address)
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readPosition = 20 # bypass the nonce, time, and object type
embeddedAddressVersion, varintLength = decodeVarint(data[readPosition:readPosition + 10])
readPosition += varintLength
embeddedStreamNumber, varintLength = decodeVarint(data[readPosition:readPosition + 10])
readPosition += varintLength
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# We'll store the address version and stream number (and some more) in the pubkeys table.
storedData = data[20:readPosition]
if addressVersion != embeddedAddressVersion:
logger.info('Pubkey decryption was UNsuccessful due to address version mismatch.')
return 'failed'
if streamNumber != embeddedStreamNumber:
logger.info('Pubkey decryption was UNsuccessful due to stream number mismatch.')
return 'failed'
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tag = data[readPosition:readPosition + 32]
readPosition += 32
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# the time through the tag. More data is appended onto signedData below after the decryption.
signedData = data[8:readPosition]
encryptedData = data[readPosition:]
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# Let us try to decrypt the pubkey
toAddress, cryptorObject = state.neededPubkeys[tag]
if toAddress != address:
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logger.critical(
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'decryptAndCheckPubkeyPayload failed due to toAddress mismatch.'
' This is very peculiar. toAddress: %s, address %s',
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toAddress,
address)
# the only way I can think that this could happen is if someone encodes their address data two different
# ways. That sort of address-malleability should have been caught by the UI or API and an error given to
# the user.
return 'failed'
try:
decryptedData = cryptorObject.decrypt(encryptedData)
except:
# Someone must have encrypted some data with a different key
# but tagged it with a tag for which we are watching.
logger.info('Pubkey decryption was unsuccessful.')
return 'failed'
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readPosition = 0
bitfieldBehaviors = decryptedData[readPosition:readPosition + 4]
readPosition += 4
publicSigningKey = '\x04' + decryptedData[readPosition:readPosition + 64]
readPosition += 64
publicEncryptionKey = '\x04' + decryptedData[readPosition:readPosition + 64]
readPosition += 64
specifiedNonceTrialsPerByte, specifiedNonceTrialsPerByteLength = decodeVarint(
decryptedData[readPosition:readPosition + 10])
readPosition += specifiedNonceTrialsPerByteLength
specifiedPayloadLengthExtraBytes, specifiedPayloadLengthExtraBytesLength = decodeVarint(
decryptedData[readPosition:readPosition + 10])
readPosition += specifiedPayloadLengthExtraBytesLength
storedData += decryptedData[:readPosition]
signedData += decryptedData[:readPosition]
signatureLength, signatureLengthLength = decodeVarint(
decryptedData[readPosition:readPosition + 10])
readPosition += signatureLengthLength
signature = decryptedData[readPosition:readPosition + signatureLength]
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if highlevelcrypto.verify(signedData, signature, hexlify(publicSigningKey)):
logger.info('ECDSA verify passed (within decryptAndCheckPubkeyPayload)')
else:
logger.info('ECDSA verify failed (within decryptAndCheckPubkeyPayload)')
return 'failed'
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sha = hashlib.new('sha512')
sha.update(publicSigningKey + publicEncryptionKey)
ripeHasher = hashlib.new('ripemd160')
ripeHasher.update(sha.digest())
embeddedRipe = ripeHasher.digest()
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if embeddedRipe != ripe:
# Although this pubkey object had the tag were were looking for and was
# encrypted with the correct encryption key, it doesn't contain the
# correct pubkeys. Someone is either being malicious or using buggy software.
logger.info('Pubkey decryption was UNsuccessful due to RIPE mismatch.')
return 'failed'
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# Everything checked out. Insert it into the pubkeys table.
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logger.info(
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os.linesep.join([
'within decryptAndCheckPubkeyPayload,'
' addressVersion: %s, streamNumber: %s' % addressVersion, streamNumber,
'ripe %s' % hexlify(ripe),
'publicSigningKey in hex: %s' % hexlify(publicSigningKey),
'publicEncryptionKey in hex: %s' % hexlify(publicEncryptionKey),
])
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)
t = (address, addressVersion, storedData, int(time.time()), 'yes')
sqlExecute('''INSERT INTO pubkeys VALUES (?,?,?,?,?)''', *t)
return 'successful'
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except varintDecodeError:
logger.info('Pubkey decryption was UNsuccessful due to a malformed varint.')
return 'failed'
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except Exception:
logger.critical(
'Pubkey decryption was UNsuccessful because of an unhandled exception! This is definitely a bug! \n%s',
traceback.format_exc())
return 'failed'
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# sslProtocolVersion
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if sys.version_info >= (2, 7, 13):
# this means TLSv1 or higher
# in the future change to
# ssl.PROTOCOL_TLS1.2
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sslProtocolVersion = ssl.PROTOCOL_TLS # pylint: disable=no-member
elif sys.version_info >= (2, 7, 9):
# this means any SSL/TLS. SSLv2 and 3 are excluded with an option after context is created
sslProtocolVersion = ssl.PROTOCOL_SSLv23
else:
# this means TLSv1, there is no way to set "TLSv1 or higher" or
# "TLSv1.2" in < 2.7.9
sslProtocolVersion = ssl.PROTOCOL_TLSv1
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# ciphers
if ssl.OPENSSL_VERSION_NUMBER >= 0x10100000 and not ssl.OPENSSL_VERSION.startswith("LibreSSL"):
sslProtocolCiphers = "AECDH-AES256-SHA@SECLEVEL=0"
else:
sslProtocolCiphers = "AECDH-AES256-SHA"