#!/usr/bin/env python3 import argparse, subprocess, json, os, urllib.request, sys, base64, binascii, \ time, hashlib, tempfile, re, copy, textwrap from urllib.request import urlopen from urllib.error import HTTPError 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@) :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" DIRECTORY = json.loads(urlopen(CA + "/directory").read().decode('utf8')) nonce_req = urllib.request.Request("{0}/directory".format(CA)) nonce_req.get_method = lambda : 'HEAD' def _b64(b): "Shortcut function to go from bytes to jwt base64 string" if type(b) is str: b = b.encode() return base64.urlsafe_b64encode(b).decode().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, universal_newlines=True) out, err = proc.communicate() if proc.returncode != 0: raise IOError("Error loading {0}".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{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.encode()).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, universal_newlines=True) out, err = proc.communicate() if proc.returncode != 0: raise IOError("Error loading {0}".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 {0}\n".format(", ".join(domains))) # Step 3: Ask user for contact email if not email: default_email = "webmaster@{0}".format(min(domains, key=len)) stdout = sys.stdout sys.stdout = sys.stderr input_email = input("STEP 1: What is your contact email? ({0}) ".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 = urllib.request.urlopen(nonce_req).headers['Replay-Nonce'] reg_raw = json.dumps({ "resource": "new-reg", "contact": ["mailto:{0}".format(email)], "agreement": DIRECTORY['meta']['terms-of-service'], }, 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("{0}.{1}".format(reg_protected64, reg_b64).encode()) 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 {0}...\n".format(domain)) id_nonce = urllib.request.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("{0}.{1}".format(id_protected64, id_b64).encode()) 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 = urllib.request.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("{0}.{1}".format(csr_protected64, csr_b64).encode()) 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 {0} {1} {2} openssl dgst -sha256 -sign user.key -out {3} {4} """.format( reg_file_sig_name, reg_file_name, "\n".join("openssl dgst -sha256 -sign user.key -out {0} {1}".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 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 {0}...\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 = "{0}/acme/new-reg".format(CA) try: resp = urllib.request.urlopen(reg_url, reg_data.encode()) result = json.loads(resp.read()) except HTTPError as e: err = e.read() # skip already registered accounts if b"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 {0}\n".format(reg_url)) sys.stderr.write(reg_data) sys.stderr.write("\n") sys.stderr.write(err.decode()) 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 {0}...\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 = "{0}/acme/new-authz".format(CA) try: resp = urllib.request.urlopen(id_url, id_data.encode()) result = json.loads(resp.read()) except HTTPError as e: sys.stderr.write("Error: id_data:\n") sys.stderr.write("POST {0}\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 = "{0}.{1}".format(challenge['token'], thumbprint) # challenge request sys.stderr.write("Building challenge responses for {0}...\n".format(i['domain'])) test_nonce = urllib.request.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("{0}.{1}".format(test_protected64, test_b64).encode()) 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/{0}".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). {0} """.format( "\n".join("openssl dgst -sha256 -sign user.key -out {0} {1}".format( i['sig_name'], i['file_name']) for i in tests))) stdout = sys.stdout sys.stdout = sys.stderr 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 {0}: Please update your server to serve the following file at this URL: -------------- URL: http://{1}/{2} File contents: \"{3}\" -------------- 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 input("Press Enter when you've got the file hosted on your server...") sys.stdout = stdout else: sys.stderr.write("""\ STEP {0}: You need to run this command on {1} (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('{2}'); \\ 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 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 {0}...\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 = urllib.request.urlopen(test_url, test_data.encode()) test_result = json.loads(resp.read()) except HTTPError as e: sys.stderr.write("Error: test_data:\n") sys.stderr.write("POST {0}\n".format(test_url)) sys.stderr.write(test_data) sys.stderr.write("\n") sys.stderr.write(e.read().decode()) sys.stderr.write("\n") raise # Step 13: Wait for CA to mark test as valid sys.stderr.write("Waiting for {0} challenge to pass...\n".format(i['domain'])) while True: try: resp = urllib.request.urlopen(test_url) challenge_status = json.loads(resp.read()) except HTTPError as e: sys.stderr.write("Error: test_data:\n") sys.stderr.write("GET {0}\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 {0} challenge!\n".format(i['domain'])) break else: raise KeyError("'{0}' challenge did not pass: {1}".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 = "{0}/acme/new-cert".format(CA) try: resp = urllib.request.urlopen(csr_url, csr_data.encode()) signed_der = resp.read() except HTTPError as e: sys.stderr.write("Error: csr_data:\n") sys.stderr.write("POST {0}\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") if file_based: sys.stderr.write("You can remove the acme-challenge file from your webserver now.\n") else: 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----- {0} -----END CERTIFICATE----- """.format("\n".join(textwrap.wrap(signed_der64.decode(), 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@") 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)