#!/usr/bin/env python
import argparse, subprocess, json, os, urllib2, sys, base64, binascii, time, \
hashlib, tempfile, re, copy, textwrap
def sign_csr(pubkey, csr, email=None, file_based=False):
"""Use the ACME protocol to get an ssl certificate signed by a
certificate authority.
:param string pubkey: Path to the user account public key.
:param string csr: Path to the certificate signing request.
:param string email: An optional user account contact email
(defaults to webmaster@<shortest_domain>)
:param bool file_based: An optional flag indicating that the
hosting should be file-based rather
than providing a simple python HTTP
server.
:returns: Signed Certificate (PEM format)
:rtype: string
"""
#CA = "https://acme-staging.api.letsencrypt.org"
CA = "https://acme-v01.api.letsencrypt.org"
TERMS = "https://letsencrypt.org/documents/LE-SA-v1.0.1-July-27-2015.pdf"
nonce_req = urllib2.Request("{}/directory".format(CA))
nonce_req.get_method = lambda : 'HEAD'
def _b64(b):
"Shortcut function to go from bytes to jwt base64 string"
return base64.urlsafe_b64encode(b).replace("=", "")
# Step 1: Get account public key
sys.stderr.write("Reading pubkey file...\n")
proc = subprocess.Popen(["openssl", "rsa", "-pubin", "-in", pubkey, "-noout", "-text"],
stdout=subprocess.PIPE, stderr=subprocess.PIPE)
out, err = proc.communicate()
if proc.returncode != 0:
raise IOError("Error loading {}".format(pubkey))
pub_hex, pub_exp = re.search(
"Modulus(?: \((?:2048|4096) bit\)|)\:\s+00:([a-f0-9\:\s]+?)Exponent\: ([0-9]+)",
out, re.MULTILINE|re.DOTALL).groups()
pub_mod = binascii.unhexlify(re.sub("(\s|:)", "", pub_hex))
pub_mod64 = _b64(pub_mod)
pub_exp = int(pub_exp)
pub_exp = "{0:x}".format(pub_exp)
pub_exp = "0{}".format(pub_exp) if len(pub_exp) % 2 else pub_exp
pub_exp = binascii.unhexlify(pub_exp)
pub_exp64 = _b64(pub_exp)
header = {
"alg": "RS256",
"jwk": {
"e": pub_exp64,
"kty": "RSA",
"n": pub_mod64,
},
}
accountkey_json = json.dumps(header['jwk'], sort_keys=True, separators=(',', ':'))
thumbprint = _b64(hashlib.sha256(accountkey_json).digest())
sys.stderr.write("Found public key!\n")
# Step 2: Get the domain names to be certified
sys.stderr.write("Reading csr file...\n")
proc = subprocess.Popen(["openssl", "req", "-in", csr, "-noout", "-text"],
stdout=subprocess.PIPE, stderr=subprocess.PIPE)
out, err = proc.communicate()
if proc.returncode != 0:
raise IOError("Error loading {}".format(csr))
domains = set([])
common_name = re.search("Subject:.*? CN=([^\s,;/]+)", out)
if common_name is not None:
domains.add(common_name.group(1))
subject_alt_names = re.search("X509v3 Subject Alternative Name: \n +([^\n]+)\n", out, re.MULTILINE|re.DOTALL)
if subject_alt_names is not None:
for san in subject_alt_names.group(1).split(", "):
if san.startswith("DNS:"):
domains.add(san[4:])
sys.stderr.write("Found domains {}\n".format(", ".join(domains)))
# Step 3: Ask user for contact email
if not email:
default_email = "webmaster@{}".format(min(domains, key=len))
stdout = sys.stdout
sys.stdout = sys.stderr
input_email = raw_input("STEP 1: What is your contact email? ({}) ".format(default_email))
email = input_email if input_email else default_email
sys.stdout = stdout
# Step 4: Generate the payloads that need to be signed
# registration
sys.stderr.write("Building request payloads...\n")
reg_nonce = urllib2.urlopen(nonce_req).headers['Replay-Nonce']
reg_raw = json.dumps({
"resource": "new-reg",
"contact": ["mailto:{}".format(email)],
"agreement": TERMS,
}, sort_keys=True, indent=4)
reg_b64 = _b64(reg_raw)
reg_protected = copy.deepcopy(header)
reg_protected.update({"nonce": reg_nonce})
reg_protected64 = _b64(json.dumps(reg_protected, sort_keys=True, indent=4))
reg_file = tempfile.NamedTemporaryFile(dir=".", prefix="register_", suffix=".json")
reg_file.write("{}.{}".format(reg_protected64, reg_b64))
reg_file.flush()
reg_file_name = os.path.basename(reg_file.name)
reg_file_sig = tempfile.NamedTemporaryFile(dir=".", prefix="register_", suffix=".sig")
reg_file_sig_name = os.path.basename(reg_file_sig.name)
# need signature for each domain identifiers
ids = []
for domain in domains:
sys.stderr.write("Building request for {}...\n".format(domain))
id_nonce = urllib2.urlopen(nonce_req).headers['Replay-Nonce']
id_raw = json.dumps({
"resource": "new-authz",
"identifier": {
"type": "dns",
"value": domain,
},
}, sort_keys=True)
id_b64 = _b64(id_raw)
id_protected = copy.deepcopy(header)
id_protected.update({"nonce": id_nonce})
id_protected64 = _b64(json.dumps(id_protected, sort_keys=True, indent=4))
id_file = tempfile.NamedTemporaryFile(dir=".", prefix="domain_", suffix=".json")
id_file.write("{}.{}".format(id_protected64, id_b64))
id_file.flush()
id_file_name = os.path.basename(id_file.name)
id_file_sig = tempfile.NamedTemporaryFile(dir=".", prefix="domain_", suffix=".sig")
id_file_sig_name = os.path.basename(id_file_sig.name)
ids.append({
"domain": domain,
"protected64": id_protected64,
"data64": id_b64,
"file": id_file,
"file_name": id_file_name,
"sig": id_file_sig,
"sig_name": id_file_sig_name,
})
# need signature for the final certificate issuance
sys.stderr.write("Building request for CSR...\n")
proc = subprocess.Popen(["openssl", "req", "-in", csr, "-outform", "DER"],
stdout=subprocess.PIPE, stderr=subprocess.PIPE)
csr_der, err = proc.communicate()
csr_der64 = _b64(csr_der)
csr_nonce = urllib2.urlopen(nonce_req).headers['Replay-Nonce']
csr_raw = json.dumps({
"resource": "new-cert",
"csr": csr_der64,
}, sort_keys=True, indent=4)
csr_b64 = _b64(csr_raw)
csr_protected = copy.deepcopy(header)
csr_protected.update({"nonce": csr_nonce})
csr_protected64 = _b64(json.dumps(csr_protected, sort_keys=True, indent=4))
csr_file = tempfile.NamedTemporaryFile(dir=".", prefix="cert_", suffix=".json")
csr_file.write("{}.{}".format(csr_protected64, csr_b64))
csr_file.flush()
csr_file_name = os.path.basename(csr_file.name)
csr_file_sig = tempfile.NamedTemporaryFile(dir=".", prefix="cert_", suffix=".sig")
csr_file_sig_name = os.path.basename(csr_file_sig.name)
# Step 5: Ask the user to sign the registration and requests
sys.stderr.write("""\
STEP 2: You need to sign some files (replace 'user.key' with your user private key).
openssl dgst -sha256 -sign user.key -out {} {}
{}
openssl dgst -sha256 -sign user.key -out {} {}
""".format(
reg_file_sig_name, reg_file_name,
"\n".join("openssl dgst -sha256 -sign user.key -out {} {}".format(i['sig_name'], i['file_name']) for i in ids),
csr_file_sig_name, csr_file_name))
stdout = sys.stdout
sys.stdout = sys.stderr
raw_input("Press Enter when you've run the above commands in a new terminal window...")
sys.stdout = stdout
# Step 6: Load the signatures
reg_file_sig.seek(0)
reg_sig64 = _b64(reg_file_sig.read())
for n, i in enumerate(ids):
i['sig'].seek(0)
i['sig64'] = _b64(i['sig'].read())
# Step 7: Register the user
sys.stderr.write("Registering {}...\n".format(email))
reg_data = json.dumps({
"header": header,
"protected": reg_protected64,
"payload": reg_b64,
"signature": reg_sig64,
}, sort_keys=True, indent=4)
reg_url = "{}/acme/new-reg".format(CA)
try:
resp = urllib2.urlopen(reg_url, reg_data)
result = json.loads(resp.read())
except urllib2.HTTPError as e:
err = e.read()
# skip already registered accounts
if "Registration key is already in use" in err:
sys.stderr.write("Already registered. Skipping...\n")
else:
sys.stderr.write("Error: reg_data:\n")
sys.stderr.write("POST {}\n".format(reg_url))
sys.stderr.write(reg_data)
sys.stderr.write("\n")
sys.stderr.write(err)
sys.stderr.write("\n")
raise
# Step 8: Request challenges for each domain
responses = []
tests = []
for n, i in enumerate(ids):
sys.stderr.write("Requesting challenges for {}...\n".format(i['domain']))
id_data = json.dumps({
"header": header,
"protected": i['protected64'],
"payload": i['data64'],
"signature": i['sig64'],
}, sort_keys=True, indent=4)
id_url = "{}/acme/new-authz".format(CA)
try:
resp = urllib2.urlopen(id_url, id_data)
result = json.loads(resp.read())
except urllib2.HTTPError as e:
sys.stderr.write("Error: id_data:\n")
sys.stderr.write("POST {}\n".format(id_url))
sys.stderr.write(id_data)
sys.stderr.write("\n")
sys.stderr.write(e.read())
sys.stderr.write("\n")
raise
challenge = [c for c in result['challenges'] if c['type'] == "http-01"][0]
keyauthorization = "{}.{}".format(challenge['token'], thumbprint)
# challenge request
sys.stderr.write("Building challenge responses for {}...\n".format(i['domain']))
test_nonce = urllib2.urlopen(nonce_req).headers['Replay-Nonce']
test_raw = json.dumps({
"resource": "challenge",
"keyAuthorization": keyauthorization,
}, sort_keys=True, indent=4)
test_b64 = _b64(test_raw)
test_protected = copy.deepcopy(header)
test_protected.update({"nonce": test_nonce})
test_protected64 = _b64(json.dumps(test_protected, sort_keys=True, indent=4))
test_file = tempfile.NamedTemporaryFile(dir=".", prefix="challenge_", suffix=".json")
test_file.write("{}.{}".format(test_protected64, test_b64))
test_file.flush()
test_file_name = os.path.basename(test_file.name)
test_file_sig = tempfile.NamedTemporaryFile(dir=".", prefix="challenge_", suffix=".sig")
test_file_sig_name = os.path.basename(test_file_sig.name)
tests.append({
"uri": challenge['uri'],
"protected64": test_protected64,
"data64": test_b64,
"file": test_file,
"file_name": test_file_name,
"sig": test_file_sig,
"sig_name": test_file_sig_name,
})
# challenge response for server
responses.append({
"uri": ".well-known/acme-challenge/{}".format(challenge['token']),
"data": keyauthorization,
})
# Step 9: Ask the user to sign the challenge responses
sys.stderr.write("""\
STEP 3: You need to sign some more files (replace 'user.key' with your user private key).
{}
""".format(
"\n".join("openssl dgst -sha256 -sign user.key -out {} {}".format(
i['sig_name'], i['file_name']) for i in tests)))
stdout = sys.stdout
sys.stdout = sys.stderr
raw_input("Press Enter when you've run the above commands in a new terminal window...")
sys.stdout = stdout
# Step 10: Load the response signatures
for n, i in enumerate(ids):
tests[n]['sig'].seek(0)
tests[n]['sig64'] = _b64(tests[n]['sig'].read())
# Step 11: Ask the user to host the token on their server
for n, i in enumerate(ids):
if file_based:
sys.stderr.write("""\
STEP {}: Please update your server to serve the following file at this URL:
--------------
URL: http://{}/{}
File contents: \"{}\"
--------------
Notes:
- Do not include the quotes in the file.
- The file should be one line without any spaces.
""".format(n + 4, i['domain'], responses[n]['uri'], responses[n]['data']))
stdout = sys.stdout
sys.stdout = sys.stderr
raw_input("Press Enter when you've got the file hosted on your server...")
sys.stdout = stdout
else:
sys.stderr.write("""\
STEP {}: You need to run this command on {} (don't stop the python command until the next step).
sudo python -c "import BaseHTTPServer; \\
h = BaseHTTPServer.BaseHTTPRequestHandler; \\
h.do_GET = lambda r: r.send_response(200) or r.end_headers() or r.wfile.write('{}'); \\
s = BaseHTTPServer.HTTPServer(('0.0.0.0', 80), h); \\
s.serve_forever()"
""".format(n + 4, i['domain'], responses[n]['data']))
stdout = sys.stdout
sys.stdout = sys.stderr
raw_input("Press Enter when you've got the python command running on your server...")
sys.stdout = stdout
# Step 12: Let the CA know you're ready for the challenge
sys.stderr.write("Requesting verification for {}...\n".format(i['domain']))
test_data = json.dumps({
"header": header,
"protected": tests[n]['protected64'],
"payload": tests[n]['data64'],
"signature": tests[n]['sig64'],
}, sort_keys=True, indent=4)
test_url = tests[n]['uri']
try:
resp = urllib2.urlopen(test_url, test_data)
test_result = json.loads(resp.read())
except urllib2.HTTPError as e:
sys.stderr.write("Error: test_data:\n")
sys.stderr.write("POST {}\n".format(test_url))
sys.stderr.write(test_data)
sys.stderr.write("\n")
sys.stderr.write(e.read())
sys.stderr.write("\n")
raise
# Step 13: Wait for CA to mark test as valid
sys.stderr.write("Waiting for {} challenge to pass...\n".format(i['domain']))
while True:
try:
resp = urllib2.urlopen(test_url)
challenge_status = json.loads(resp.read())
except urllib2.HTTPError as e:
sys.stderr.write("Error: test_data:\n")
sys.stderr.write("GET {}\n".format(test_url))
sys.stderr.write(test_data)
sys.stderr.write("\n")
sys.stderr.write(e.read())
sys.stderr.write("\n")
raise
if challenge_status['status'] == "pending":
time.sleep(2)
elif challenge_status['status'] == "valid":
sys.stderr.write("Passed {} challenge!\n".format(i['domain']))
break
else:
raise KeyError("'{}' challenge did not pass: {}".format(i['domain'], challenge_status))
# Step 14: Get the certificate signed
sys.stderr.write("Requesting signature...\n")
csr_file_sig.seek(0)
csr_sig64 = _b64(csr_file_sig.read())
csr_data = json.dumps({
"header": header,
"protected": csr_protected64,
"payload": csr_b64,
"signature": csr_sig64,
}, sort_keys=True, indent=4)
csr_url = "{}/acme/new-cert".format(CA)
try:
resp = urllib2.urlopen(csr_url, csr_data)
signed_der = resp.read()
except urllib2.HTTPError as e:
sys.stderr.write("Error: csr_data:\n")
sys.stderr.write("POST {}\n".format(csr_url))
sys.stderr.write(csr_data)
sys.stderr.write("\n")
sys.stderr.write(e.read())
sys.stderr.write("\n")
raise
# Step 15: Convert the signed cert from DER to PEM
sys.stderr.write("Certificate signed!\n")
sys.stderr.write("You can stop running the python command on your server (Ctrl+C works).\n")
signed_der64 = base64.b64encode(signed_der)
signed_pem = """\
-----BEGIN CERTIFICATE-----
{}
-----END CERTIFICATE-----
""".format("\n".join(textwrap.wrap(signed_der64, 64)))
return signed_pem
if __name__ == "__main__":
parser = argparse.ArgumentParser(
formatter_class=argparse.RawDescriptionHelpFormatter,
description="""\
Get a SSL certificate signed by a Let's Encrypt (ACME) certificate authority and
output that signed certificate. You do NOT need to run this script on your
server and this script does not ask for your private keys. It will print out
commands that you need to run with your private key or on your server as root,
which gives you a chance to review the commands instead of trusting this script.
NOTE: YOUR ACCOUNT KEY NEEDS TO BE DIFFERENT FROM YOUR DOMAIN KEY.
Prerequisites:
* openssl
* python
Example: Generate an account keypair, a domain key and csr, and have the domain csr signed.
--------------
$ openssl genrsa 4096 > user.key
$ openssl rsa -in user.key -pubout > user.pub
$ openssl genrsa 4096 > domain.key
$ openssl req -new -sha256 -key domain.key -subj "/CN=example.com" > domain.csr
$ python sign_csr.py --public-key user.pub domain.csr > signed.crt
--------------
""")
parser.add_argument("-p", "--public-key", required=True, help="path to your account public key")
parser.add_argument("-e", "--email", default=None, help="contact email, default is webmaster@<shortest_domain>")
parser.add_argument("-f", "--file-based", action='store_true', help="if set, a file-based response is used")
parser.add_argument("csr_path", help="path to your certificate signing request")
args = parser.parse_args()
signed_crt = sign_csr(args.public_key, args.csr_path, email=args.email, file_based=args.file_based)
sys.stdout.write(signed_crt)
