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certbot/server-ca/CSR.py

226 lines
6.7 KiB
Python

#!/usr/bin/env python
# use OpenSSL to provide CSR-related operations
import site, os
assert os.path.exists("../m3/lib/python"), "\nPlease install m3crypto into ../m3/lib/python by running\nmkdir -p ../m3/lib/python; PYTHONPATH=../m3/lib/python python setup.py install --home=../m3\nfrom inside the m3crypto directory."
site.addsitedir("../m3/lib/python")
import subprocess, tempfile, re
import M2Crypto
from distutils.version import LooseVersion
assert LooseVersion(M2Crypto.version) >= LooseVersion("0.22")
import hashlib
# we can use tempfile.NamedTemporaryFile() to get tempfiles
# to pass to OpenSSL subprocesses.
def parse(csr):
"""
Is this CSR syntactically valid? (TODO: remove)
@type csr: str
@param csr: PEM-encoded string of the CSR.
@return: True if M2Crypto can parse the csr,
False if there is an error parsing it.
"""
try:
csr = str(csr)
req = M2Crypto.X509.load_request_string(csr)
return True
except Exception, e:
return False
def modulusbits(key):
key = str(key)
"""How many bits are in the modulus of this key?"""
bio = M2Crypto.BIO.MemoryBuffer(key)
pubkey = M2Crypto.RSA.load_pub_key_bio(bio)
return len(pubkey)
def goodkey(key):
"""Does this public key comply with our CA policy?"""
key = str(key)
bits = modulusbits(key)
if bits and bits >= 2000:
return True
else:
return False
def csr_goodkey(csr):
"""Does this CSR's embedded public key comply with our CA policy?"""
csr = str(csr)
if not parse(csr): return False
key = pubkey(csr)
return goodkey(key)
def pubkey(csr):
"""
Get the public key from this Certificate Signing Request.
@type csr: string
@param csr: PEM-encoded string of the CSR.
@return: a string of the PEM-encoded public key
"""
csr = str(csr)
req = M2Crypto.X509.load_request_string(csr)
return req.get_pubkey().get_rsa().as_pem(None)
def subject(csr):
"""
Get the X.509 subject from this CSR.
@type csr: string
@param csr: PEM-encoded string of the CSR.
@return: a string of the subject
"""
csr = str(csr)
req = M2Crypto.X509.load_request_string(csr)
return req.get_subject().as_text()
def cn(csr):
"""
Get the common name from this CSR. Requires there be exactly one CN
(of type ASN1_string)
@type csr: str
@param csr: PEM-encoded string of the CSR.
@return: string of the first
"""
csr = str(csr)
req = M2Crypto.X509.load_request_string(csr)
# Get an array of CNs
cns = req.get_subject().get_entries_by_nid(M2Crypto.X509.X509_Name.nid['CN'])
# If it's not 1, we've got problems (throw error?)
if len(cns) != 1:
return None
return cns[0].get_data().as_text()
def subject_names(csr):
"""
Get the cn and subjectAltNames from this CSR.
@type csr: str
@param csr: PEM-encoded string of the CSR
@return: array of strings of subject (CN) and subject
alternative names (x509 extension)
"""
csr = str(csr)
names = []
names.append(cn(csr))
req = M2Crypto.X509.load_request_string(csr)
for ext in req.get_extensions(): # requires M3Crypto modification
if ext.get_name() == 'subjectAltName': # TODO: can we trust this?
# 'DNS:example.com, DNS:www.example.com'
sans = ext.get_value().split(',')
for san in sans:
san = san.strip() # remove leading space
if san.startswith('DNS:'):
names.append(san[len('DNS:'):])
# Don't exit loop - support multiple SAN extensions??
return names
def can_sign(name):
"""Does this CA's policy forbid signing this name via Chocolate DV?"""
# We could have a regular expression match here, like
# ([a-z0-9]+\.)+[a-z0-9]+
# and there is also a list of TLDs to check against to confirm that
# the name is actually a FQDN.
name = str(name)
if "." not in name: return False
# Examples of names that are forbidden by policy due to a blacklist.
if name in ["google.com", "www.google.com"]: return False
return True
def verify(key, data, signature):
"""
Given a public key, some data, and its signature,
verify the signature.
@type key: str
@param key: PEM-encoded string of the public key.
@type data: str
@param data: The data (before being hashed; we will use sha256 here)
@type signature: str
@param signature: binary string of the signature
@return: True if the signature checks out, False otherwise.
"""
key = str(key)
data = str(data)
signature = str(signature)
bio = M2Crypto.BIO.MemoryBuffer(key)
pubkey = M2Crypto.RSA.load_pub_key_bio(bio)
try:
res = pubkey.verify(hashlib.sha256(data).digest(), signature, 'sha256')
except M2Crypto.RSA.RSAError:
return False
return (res == 1)
def sign(key, data):
"""
Sign this data with this private key. For client-side use.
@type key: str
@param key: PEM-encoded string of the private key.
@type data: str
@param data: The data to be signed. Will be hashed (sha256) prior to
signing.
@return: binary string of the signature
"""
key = str(key)
data = str(data)
privkey = M2Crypto.RSA.load_key_string(key)
return privkey.sign(hashlib.sha256(data).digest(), 'sha256')
def encrypt(key, data):
"""
Encrypt this data with this public key.
@type key: str
@param key: PEM-encoded string of the public key
@type data: str
@param data: The data to be encrypted.
@return: binary string of the encrypted value, using PKCS1_OAEP_PADDING
"""
key = str(key)
data = str(data)
bio = M2Crypto.BIO.MemoryBuffer(key)
pubkey = M2Crypto.RSA.load_pub_key_bio(bio)
return pubkey.public_encrypt(data, M2Crypto.RSA.pkcs1_oaep_padding)
def issue(csr):
"""Issue the certificate requested by this CSR and return it!"""
# TODO: a real CA should severely restrict the content of the cert, not
# just grant what's asked for. (For example, the CA shouldn't trust
# all the data in the subject field if it hasn't been validated.)
# Therefore, we should construct a new CSR from scratch using the
# parsed-out data from the input CSR, and then pass that to OpenSSL.
csr = str(csr)
cert = None
with tempfile.NamedTemporaryFile() as csr_tmp:
csr_tmp.write(csr)
csr_tmp.flush()
with tempfile.NamedTemporaryFile() as cert_tmp:
ret = subprocess.Popen(["./CA.sh", "-chocolate", csr_tmp.name, cert_tmp.name],shell=False,stdin=subprocess.PIPE,stdout=subprocess.PIPE,stderr=subprocess.PIPE).wait()
if ret == 0:
cert = cert_tmp.read()
return cert