sign_csr.py

#!/usr/bin/env python
import argparse, subprocess, json, os, urllib2, sys, base64, binascii, ssl, \
    hashlib, tempfile, re, time, copy, textwrap
from threading import Thread
from BaseHTTPServer import HTTPServer,BaseHTTPRequestHandler

def sign_csr(pubkey, csr, privkey, email=None, automatized=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>)

    :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
        if automatized:
            email=default_email
        else:
            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
    privkey_path='user.key' if privkey==None else privkey # privkey can be None only if atomatized==True
    sys.stderr.write("""\
STEP 2: You need to sign some files{}.

openssl dgst -sha256 -sign {} -out {} {}
{}
openssl dgst -sha256 -sign {} -out {} {}

""".format(
    ' (replace \'user.key\' with your user private key).' if not privkey else '',\
    privkey_path,reg_file_sig_name, reg_file_name,
    "\n".join("openssl dgst -sha256 -sign {} -out {} {}".format(privkey_path,i['sig_name'], i['file_name']) for i in ids),
    privkey_path,csr_file_sig_name, csr_file_name))

    stdout = sys.stdout
    sys.stdout = sys.stderr
    if automatized:
        toSign=ids[:]
        toSign.append({'sig_name':reg_file_sig_name,'file_name':reg_file_name})
        toSign.append({'sig_name':csr_file_sig_name,'file_name':csr_file_name})
        print 'Signing',len(toSign),'files.\n'
        for i in toSign:
            subprocess.Popen(['openssl','dgst','-sha256','-sign',privkey_path,'-out',i['sig_name'],i['file_name']],stdout=subprocess.PIPE,stderr=subprocess.PIPE).communicate()
    else:
        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{}.

{}

""".format(
    ' (replace \'user.key\' with your user private key).' if not privkey else '',\
    "\n".join("openssl dgst -sha256 -sign {} -out {} {}".format(
        privkey_path,i['sig_name'], i['file_name']) for i in tests)))

    stdout = sys.stdout
    sys.stdout = sys.stderr
    if automatized:
        print 'Signing',len(responses),'files.\n'
        for i in tests:
            subprocess.Popen(['openssl','dgst','-sha256','-sign',privkey_path,'-out',i['sig_name'],i['file_name']],stdout=subprocess.PIPE,stderr=subprocess.PIPE).communicate()
    else:
        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):
        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
        if automatized:
            print 'starting web server on port 80'
            def httpd(token):
                h=BaseHTTPRequestHandler
                h.do_GET=lambda r: r.send_response(200) or r.end_headers() or r.wfile.write(token);
                s=HTTPServer(('0.0.0.0',80),h);
                s.handle_request()
            t=Thread(target=httpd,args=(responses[n]['data'].replace('\\"','"'),))
            t.start()
        else:
            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("\nRequesting 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")
    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.

Optionally you can decide to trust this script and run it on your server as root
and use --trust switch. This allows you to have certificate signed in singe command.

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('--trust',action='store_true',default=False,help='complete chalanges automaticaly')
    parser.add_argument('-w',dest='crt_path',action='store',help='write output to file')
    parser.add_argument("-p","--public-key",action="store",required=True,help="path to your account public key")
    parser.add_argument("-k","--private-key",action="store",default=None,help='path to your account private key')
    parser.add_argument("-e","--email",action="store",default=None, help="contact email, default is webmaster@<shortest_domain>")
    parser.add_argument("-c","--chain",action='store_true',default=False, help="Append Lets Encrypt Authority X3 certificate")
    parser.add_argument("csr_path", action="store",help="path to your certificate signing request")

    args = parser.parse_args()
    if args.trust:
        if args.private_key==None:
            print 'Define path to account private key with -k or --private-key. This is needed to sign challenges\nautomaticaly. You also to sign them manualy if you run program without --trust swith.'
            exit()
        if os.geteuid()!=0:
            print 'Run as root or without --trust switch'
            exit()
    signed_crt = sign_csr(args.public_key, args.csr_path, args.private_key, email=args.email, automatized=args.trust)

    if args.chain:
        signed_crt+="""\
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
"""
    if args.crt_path:
        print 'Saving signed certificate in',args.crt_path
        crtFile=open(args.crt_path,'w')
        crtFile.write(signed_crt)
        crtFile.close()
    else:
        sys.stdout.write(signed_crt)