sign_csr.py: Refactor script to use acmev2.

Initial version.

1 files changed, 145 insertions, 343 deletions

diff --git a/sign_csr.py b/sign_csr.py
index be9dfd4..17654d3 100644
--- a/sign_csr.py
+++ b/sign_csr.py
@@ -5,28 +5,22 @@ import argparse, subprocess, json, os, urllib.request, sys, base64, binascii, \
 from urllib.request import urlopen
 from urllib.error import HTTPError
 
-def sign_csr(pubkey, csr, email=None, file_based=False):
+def sign_csr(account_key, csr, email=None):
     """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 account_key: Path to the user account 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"
+    #CA = "https://acme-staging-v02.api.letsencrypt.org"
+    CA = "https://acme-v02.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"
@@ -35,16 +29,63 @@ def sign_csr(pubkey, csr, email=None, file_based=False):
 
         return base64.urlsafe_b64encode(b).decode().replace("=", "")
 
+    # helper function - run external commands
+    def _cmd(cmd_list, stdin=None, cmd_input=None, err_msg="Command Line Error"):
+        proc = subprocess.Popen(cmd_list, stdin=stdin, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+        out, err = proc.communicate(cmd_input)
+        if proc.returncode != 0:
+            raise IOError("{0}\n{1}".format(err_msg, err))
+        return out
+
+    # helper function - make request and automatically parse json response
+    def _do_request(url, data=None, err_msg="Error", depth=0):
+        try:
+            resp = urllib.request.urlopen(urllib.request.Request(url, data=data, headers={"Content-Type": "application/jose+json", "User-Agent": "acme-nosudo"}))
+            resp_data, code, headers = resp.read().decode("utf8"), resp.getcode(), resp.headers
+        except IOError as e:
+            resp_data = e.read().decode("utf8") if hasattr(e, "read") else str(e)
+            code, headers = getattr(e, "code", None), {}
+        try:
+            resp_data = json.loads(resp_data) # try to parse json results
+        except ValueError:
+            pass # ignore json parsing errors
+        if depth < 100 and code == 400 and resp_data['type'] == "urn:ietf:params:acme:error:badNonce":
+            raise IndexError(resp_data) # allow 100 retrys for bad nonces
+        if code not in [200, 201, 204]:
+            raise ValueError("{0}:\nUrl: {1}\nData: {2}\nResponse Code: {3}\nResponse: {4}".format(err_msg, url, data, code, resp_data))
+        return resp_data, code, headers
+
+    # helper function - make signed requests
+    def _send_signed_request(url, payload, err_msg, depth=0):
+        payload64 = "" if payload is None else _b64(json.dumps(payload).encode('utf8'))
+        new_nonce = _do_request(DIRECTORY['newNonce'])[2]['Replay-Nonce']
+        protected = {"url": url, "alg": "RS256", "nonce": new_nonce}
+        protected.update({"jwk": jwk} if acct_headers is None else {"kid": acct_headers['Location']})
+        protected64 = _b64(json.dumps(protected).encode('utf8'))
+        protected_input = "{0}.{1}".format(protected64, payload64).encode('utf8')
+        out = _cmd(["openssl", "dgst", "-sha256", "-sign", account_key], stdin=subprocess.PIPE, cmd_input=protected_input, err_msg="OpenSSL Error")
+        data = json.dumps({"protected": protected64, "payload": payload64, "signature": _b64(out)})
+        try:
+            return _do_request(url, data=data.encode('utf8'), err_msg=err_msg, depth=depth)
+        except IndexError: # retry bad nonces (they raise IndexError)
+            return _send_signed_request(url, payload, err_msg, depth=(depth + 1))
+
+    # helper function - poll until complete
+    def _poll_until_not(url, pending_statuses, err_msg):
+        result, t0 = None, time.time()
+        while result is None or result['status'] in pending_statuses:
+            assert (time.time() - t0 < 3600), "Polling timeout" # 1 hour timeout
+            time.sleep(0 if result is None else 2)
+            result, _, _ = _send_signed_request(url, None, err_msg)
+        return result
+
+
     # 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))
+    out = _cmd(["openssl", "rsa", "-in", account_key, "-noout", "-text"], err_msg="Error reading account public key")
     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()
+        r"modulus:[\s]+?00:([a-f0-9\:\s]+?)\npublicExponent: ([0-9]+)",
+        out.decode('utf8'), re.MULTILINE|re.DOTALL).groups()
     pub_mod = binascii.unhexlify(re.sub("(\s|:)", "", pub_hex))
     pub_mod64 = _b64(pub_mod)
     pub_exp = int(pub_exp)
@@ -52,30 +93,23 @@ def sign_csr(pubkey, csr, email=None, file_based=False):
     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,
-        },
+    jwk = {
+        "e": pub_exp64,
+        "kty": "RSA",
+        "n": pub_mod64,
     }
-    accountkey_json = json.dumps(header['jwk'], sort_keys=True, separators=(',', ':'))
+    accountkey_json = json.dumps(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))
+    out = _cmd(["openssl", "req", "-in", csr, "-noout", "-text"], err_msg="Error loading {}".format(csr))
     domains = set([])
-    common_name = re.search("Subject:.*? CN *= *([^\s,;/]+)", out)
+    common_name = re.search("Subject:.*? CN *= *([^\s,;/]+)", out.decode('utf8'))
     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)
+    subject_alt_names = re.search("X509v3 Subject Alternative Name: \n +([^\n]+)\n", out.decode('utf8'), re.MULTILINE|re.DOTALL)
     if subject_alt_names is not None:
         for san in subject_alt_names.group(1).split(", "):
             if san.startswith("DNS:"):
@@ -91,328 +125,97 @@ def sign_csr(pubkey, csr, email=None, file_based=False):
         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 = []
+
+    # Step 4: Generate the payload for registering user and initiate registration.
+    sys.stderr.write("Registering {0}...\n".format(email))
+    reg = {
+        "termsOfServiceAgreed": True
+    }
+    acct_headers = None
+    result, code, acct_headers = _send_signed_request(DIRECTORY['newAccount'], reg, "Error registering")
+    if code == 201:
+        sys.stderr.write("Registered!\n")
+    else:
+        sys.stderr.write("Already registered!\n")
+
+
+    # Step 5: Request challenges for each domain
     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": {
+        sys.stderr.write("Making new order for {0}...\n".format(domain))
+        id = {
+            "identifiers": [{
                 "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]
+            }],
+        }
+        order, order_code, order_headers = _send_signed_request(DIRECTORY['newOrder'], id, "Error creating new order")
+
+        # Request challenges
+        sys.stderr.write("Requesting challenges...\n")
+        chl_result, chl_code, chl_headers = _send_signed_request(order['authorizations'][0], None, "Error getting challenges")
+
+        challenge = [c for c in chl_result['challenges'] if c['type'] == "http-01"][0]
+        token = re.sub(r"[^A-Za-z0-9_\-]", "_", challenge['token'])
         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,
-        })
+        # build request for the server to test this challenge.
+        test_url = challenge['url']
+        test_raw = "{}"
 
         # challenge response for server
-        responses.append({
+        response = {
             "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:
+        # Step 6: Ask the user to host the token on their server
+        sys.stderr.write("""\
+Please update your server to serve the following file at this URL:
 
 --------------
-URL: http://{1}/{2}
-File contents: \"{3}\"
+URL: http://{0}/{1}
+File contents: \"{2}\"
 --------------
 
 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']))
+""".format(domain, response['uri'], response['data']))
 
-            stdout = sys.stdout
-            sys.stdout = sys.stderr
-            input("Press Enter when you've got the file hosted on your server...")
-            sys.stdout = stdout
+        stdout = sys.stdout
+        sys.stdout = sys.stderr
+        input("Press Enter when you've got the file hosted on your server...")
+        sys.stdout = stdout
+
+        # Step 7: Let the CA know you're ready for the challenge
+        sys.stderr.write("Requesting verification for {0}...\n".format(domain))
+        _send_signed_request(challenge['url'], {}, "Error requesting challenge verfication: {0}".format(domain))
+        chl_verification = _poll_until_not(challenge['url'], ["pending"], "Error checking challenge verification")
+        if chl_verification['status'] != "valid":
+            raise ValueError("Challenge did not pass for {0}: {1}".format(domain, chl_verification))
+        sys.stderr.write("{} verified!\n".format(domain))
+
+        # Step 8: Finalize
+        csr_der = _cmd(["openssl", "req", "-in", csr, "-outform", "DER"], err_msg="DER Export Error")
+        fnlz_resp, fnlz_code, fnlz_headers = _send_signed_request(order['finalize'], {"csr": _b64(csr_der)}, "Error finalizing order")
+
+        # Step 9: Wait for CA to mark test as valid
+        sys.stderr.write("Waiting for {0} challenge to pass...\n".format(domain))
+        order = _poll_until_not(order_headers['Location'], ["pending", "processing"], "Error checking order status")
+
+        if order['status'] == "valid":
+            sys.stderr.write("Passed {0} challenge!\n".format(domain))
         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")
+            raise ValueError("'{0}' challenge did not pass: {1}".format(domain, order))
+
+
+    # Step 10: Get the certificate.
+    sys.stderr.write("Getting certificate...\n")
+    signed_pem, _, _ = _send_signed_request(order['certificate'], None, "Error getting certificate")
 
-    signed_der64 = base64.b64encode(signed_der)
-    signed_pem = """\
------BEGIN CERTIFICATE-----
-{0}
------END CERTIFICATE-----
-""".format("\n".join(textwrap.wrap(signed_der64.decode(), 64)))
+    sys.stderr.write("Received certificate!\n")
+    sys.stderr.write("You can remove the acme-challenge file from your webserver now.\n")
 
     return signed_pem
 
@@ -420,17 +223,17 @@ 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.
+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, it is meant to be run on your
+computer. The script will request you to manually deploy the acme
+challenge on your server.
 
 NOTE: YOUR ACCOUNT KEY NEEDS TO BE DIFFERENT FROM YOUR DOMAIN KEY.
 
 Prerequisites:
 * openssl
-* python
+* python version 3
 
 Example: Generate an account keypair, a domain key and csr, and have the domain csr signed.
 --------------
@@ -438,16 +241,15 @@ $ 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
+$ python3 sign_csr.py --account-key user.key --email user@example.com domain.csr > signed.crt
 --------------
 
 """)
-    parser.add_argument("-p", "--public-key", required=True, help="path to your account public key")
+    parser.add_argument("-k", "--account-key", required=True, help="path to your Let's Encrypt account private 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)
+    signed_crt = sign_csr(args.account_key, args.csr_path, email=args.email)
     sys.stdout.write(signed_crt)