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#!/usr/bin/python
# Copyright 2014-2015, The Tor Project, Inc
# See LICENSE for licensing information
# This script parses openssl headers to find ciphersuite names, determines
# which ones we should be willing to use as a server, and sorts them according
# to preference rules.
#
# Run it on all the files in your openssl include directory.
import re
import sys
EPHEMERAL_INDICATORS = [ "_EDH_", "_DHE_", "_ECDHE_" ]
BAD_STUFF = [ "_DES_40_", "MD5", "_RC4_", "_DES_64_",
"_SEED_", "_CAMELLIA_", "_NULL",
"_CCM_8", "_DES_", ]
# these never get #ifdeffed.
MANDATORY = [
"TLS1_TXT_DHE_RSA_WITH_AES_256_SHA",
"TLS1_TXT_DHE_RSA_WITH_AES_128_SHA",
"SSL3_TXT_EDH_RSA_DES_192_CBC3_SHA",
]
def find_ciphers(filename):
with open(filename) as f:
for line in f:
m = re.search(r'(?:SSL3|TLS1)_TXT_\w+', line)
if m:
yield m.group(0)
def usable_cipher(ciph):
ephemeral = False
for e in EPHEMERAL_INDICATORS:
if e in ciph:
ephemeral = True
if not ephemeral:
return False
if "_RSA_" not in ciph:
return False
for b in BAD_STUFF:
if b in ciph:
return False
return True
# All fields we sort on, in order of priority.
FIELDS = [ 'cipher', 'fwsec', 'mode', 'digest', 'bitlength' ]
# Map from sorted fields to recognized value in descending order of goodness
FIELD_VALS = { 'cipher' : [ 'AES', 'CHACHA20' ],
'fwsec' : [ 'ECDHE', 'DHE' ],
'mode' : [ 'POLY1305', 'GCM', 'CCM', 'CBC', ],
'digest' : [ 'n/a', 'SHA384', 'SHA256', 'SHA', ],
'bitlength' : [ '256', '128', '192' ],
}
class Ciphersuite(object):
def __init__(self, name, fwsec, cipher, bitlength, mode, digest):
if fwsec == 'EDH':
fwsec = 'DHE'
if mode in [ '_CBC3', '_CBC', '' ]:
mode = 'CBC'
elif mode == '_GCM':
mode = 'GCM'
self.name = name
self.fwsec = fwsec
self.cipher = cipher
self.bitlength = bitlength
self.mode = mode
self.digest = digest
for f in FIELDS:
assert(getattr(self, f) in FIELD_VALS[f])
def sort_key(self):
return tuple(FIELD_VALS[f].index(getattr(self,f)) for f in FIELDS)
def parse_cipher(ciph):
m = re.match('(?:TLS1|SSL3)_TXT_(EDH|DHE|ECDHE)_RSA(?:_WITH)?_(AES|DES)_(256|128|192)(|_CBC|_CBC3|_GCM)_(SHA|SHA256|SHA384)$', ciph)
if m:
fwsec, cipher, bits, mode, digest = m.groups()
return Ciphersuite(ciph, fwsec, cipher, bits, mode, digest)
m = re.match('(?:TLS1|SSL3)_TXT_(EDH|DHE|ECDHE)_RSA(?:_WITH)?_(AES|DES)_(256|128|192)_CCM', ciph)
if m:
fwsec, cipher, bits = m.groups()
return Ciphersuite(ciph, fwsec, cipher, bits, "CCM", "n/a")
m = re.match('(?:TLS1|SSL3)_TXT_(EDH|DHE|ECDHE)_RSA(?:_WITH)?_CHACHA20_POLY1305', ciph)
if m:
fwsec, = m.groups()
return Ciphersuite(ciph, fwsec, "CHACHA20", "256", "POLY1305", "n/a")
print "/* Couldn't parse %s ! */"%ciph
return None
ALL_CIPHERS = []
for fname in sys.argv[1:]:
for c in find_ciphers(fname):
if usable_cipher(c):
parsed = parse_cipher(c)
if parsed != None:
ALL_CIPHERS.append(parsed)
ALL_CIPHERS.sort(key=Ciphersuite.sort_key)
for c in ALL_CIPHERS:
if c is ALL_CIPHERS[-1]:
colon = ';'
else:
colon = ' ":"'
if c.name in MANDATORY:
print " /* Required */"
print ' %s%s'%(c.name,colon)
else:
print "#ifdef %s"%c.name
print ' %s%s'%(c.name,colon)
print "#endif"
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