api: Preliminary OCSP support

README.rst

@@ -69,6 +69,7 @@ Common:
 
 * Standard request, sign, revoke workflow via web interface.
 * Kerberos and basic auth based web interface authentication.
+* Preliminary `OCSP <https://tools.ietf.org/html/rfc4557>`_ and `SCEP <https://tools.ietf.org/html/draft-nourse-scep-23>`_ support.
 * PAM and Active Directory compliant authentication backends: Kerberos single sign-on, LDAP simple bind.
 * POSIX groups and Active Directory (LDAP) group membership based authorization.
 * Server-side command-line interface, check out ``certidude list``, ``certidude sign`` and ``certidude revoke``.
@@ -94,8 +95,6 @@ HTTPS:
 TODO
 ----
 
-* `OCSP <https://tools.ietf.org/html/rfc4557>`_ support, needs a bit hacking since OpenSSL wrappers are not exposing the functionality.
-* `SCEP <https://tools.ietf.org/html/draft-nourse-scep-23>`_ support, a client implementation available `here <https://github.com/certnanny/sscep>`_. Not sure if we can implement server-side events within current standard.
 * WebCrypto support, meanwhile check out `hwcrypto.js <https://github.com/open-eid/hwcrypto.js>`_.
 * Use `pki.js <https://pkijs.org/>`_ for generating keypair in the browser when claiming a token.
 * Signer process logging.

certidude/api/__init__.py

@@ -215,6 +215,10 @@ def certidude_app(log_handlers=[]):
         from .scep import SCEPResource
         app.add_route("/api/scep/", SCEPResource())
 
+    if config.OCSP_SUBNETS:
+        from .ocsp import OCSPResource
+        app.add_route("/api/ocsp/", OCSPResource())
+
     # Add sink for serving static files
     app.add_sink(StaticResource(os.path.join(__file__, "..", "..", "static")))
 

certidude/api/ocsp.py

@@ -0,0 +1,97 @@
+from __future__ import unicode_literals, division, absolute_import, print_function
+import click
+import hashlib
+import os
+from asn1crypto.util import timezone
+from datetime import datetime, timedelta
+
+from asn1crypto import cms, algos, x509, ocsp
+from base64 import b64decode, b64encode
+from certbuilder import pem_armor_certificate
+from certidude import authority, push, config
+from certidude.firewall import whitelist_subnets
+from oscrypto import keys, asymmetric, symmetric
+from oscrypto.errors import SignatureError
+
+# openssl ocsp -issuer /var/lib/certidude/ca2.koodur.lan/ca_crt.pem -cert /var/lib/certidude/ca2.koodur.lan/signed/lauri-c720p.pem -text -url http://ca2.koodur.lan/api/ocsp/
+
+class OCSPResource(object):
+    def on_post(self, req, resp):
+        fh = open(config.AUTHORITY_CERTIFICATE_PATH)
+        server_certificate = asymmetric.load_certificate(fh.read())
+        fh.close()
+
+        ocsp_req = ocsp.OCSPRequest.load(req.stream.read())
+        print(ocsp_req["tbs_request"].native)
+
+        now = datetime.now(timezone.utc)
+        response_extensions = []
+
+        for ext in ocsp_req["tbs_request"]["request_extensions"]:
+            if ext["extn_id"] == "nonce":
+                response_extensions.append(
+                    ocsp.ResponseDataExtension({
+                        'extn_id': "nonce",
+                        'critical': False,
+                        'extn_value': ext["extn_value"]
+                    })
+                )
+
+        responses = []
+        for item in ocsp_req["tbs_request"]["request_list"]:
+            serial = item["req_cert"]["serial_number"].native
+
+            try:
+                link_target = os.readlink(os.path.join(config.SIGNED_BY_SERIAL_DIR, "%x.pem" % serial))
+                assert link_target.startswith("../")
+                assert link_target.endswith(".pem")
+                path, buf, cert = authority.get_signed(link_target[3:-4])
+                if serial != cert.serial:
+                    raise EnvironmentError("integrity check failed")
+                status = ocsp.CertStatus(name='good', value=None)
+            except EnvironmentError:
+                try:
+                    path, buf, cert, revoked = authority.get_revoked(serial)
+                    status = ocsp.CertStatus(
+                        name='revoked',
+                        value={
+                            'revocation_time': revoked,
+                            'revocation_reason': "key_compromise",
+                        })
+                except EnvironmentError:
+                    status = ocsp.CertStatus(name="unknown", value=None)
+
+            responses.append({
+                'cert_id': {
+                    'hash_algorithm': {
+                        'algorithm': "sha1"
+                    },
+                    'issuer_name_hash': server_certificate.asn1.subject.sha1,
+                    'issuer_key_hash': server_certificate.public_key.asn1.sha1,
+                    'serial_number': serial,
+                },
+                'cert_status': status,
+                'this_update': now,
+                'single_extensions': []
+            })
+
+        response_data = ocsp.ResponseData({
+            'responder_id': ocsp.ResponderId(name='by_key', value=server_certificate.public_key.asn1.sha1),
+            'produced_at': now,
+            'responses': responses,
+            'response_extensions': response_extensions
+        })
+
+        resp.body = ocsp.OCSPResponse({
+            'response_status': "successful",
+            'response_bytes': {
+                'response_type': 'basic_ocsp_response',
+                'response': {
+                    'tbs_response_data': response_data,
+                    'signature_algorithm': {'algorithm': "sha1_rsa"},
+                    'signature': b64decode(authority.signer_exec("sign-pkcs7", b64encode(response_data.dump()))),
+                    'certs': [server_certificate.asn1]
+                }
+            }
+        }).dump()
+

certidude/api/request.py

@@ -139,7 +139,7 @@ class RequestListResource(object):
 
         # Attempt to save the request otherwise
         try:
-            csr = authority.store_request(body)
+            csr = authority.store_request(body.decode("ascii"))
         except errors.RequestExists:
             reasons.append("Same request already uploaded exists")
             # We should still redirect client to long poll URL below

certidude/authority.py

@@ -50,10 +50,11 @@ def get_signed(common_name):
         return path, buf, x509.load_pem_x509_certificate(buf, default_backend())
 
 def get_revoked(serial):
-    path = os.path.join(config.REVOKED_DIR, serial + ".pem")
+    path = os.path.join(config.REVOKED_DIR, "%x.pem" % serial)
     with open(path) as fh:
         buf = fh.read()
-        return path, buf, x509.load_pem_x509_certificate(buf, default_backend())
+        return path, buf, x509.load_pem_x509_certificate(buf, default_backend()), \
+            datetime.utcfromtimestamp(os.stat(path).st_ctime)
 
 
 def get_attributes(cn):
@@ -83,7 +84,7 @@ def store_request(buf, overwrite=False):
         raise ValueError("No signing request supplied")
 
     if isinstance(buf, unicode):
-        csr = x509.load_pem_x509_csr(buf, backend=default_backend())
+        csr = x509.load_pem_x509_csr(buf.encode("ascii"), backend=default_backend())
     elif isinstance(buf, str):
         csr = x509.load_der_x509_csr(buf, backend=default_backend())
         buf = csr.public_bytes(Encoding.PEM)
@@ -134,10 +135,11 @@ def revoke(common_name):
     """
     Revoke valid certificate
     """
-    path, buf, cert = get_signed(common_name)
+    signed_path, buf, cert = get_signed(common_name)
     revoked_path = os.path.join(config.REVOKED_DIR, "%x.pem" % cert.serial)
-    signed_path = os.path.join(config.SIGNED_DIR, "%s.pem" % common_name)
     os.rename(signed_path, revoked_path)
+    os.unlink(os.path.join(config.SIGNED_BY_SERIAL_DIR, "%x.pem" % cert.serial))
+
     push.publish("certificate-revoked", common_name)
 
     # Publish CRL for long polls
@@ -362,6 +364,11 @@ def _sign(csr, buf, overwrite=False):
     attachments.append((cert_buf, "application/x-pem-file", common_name.value + ".crt"))
     cert_serial_hex = "%x" % cert.serial
 
+    # Create symlink
+    os.symlink(
+        "../%s.pem" % common_name.value,
+        os.path.join(config.SIGNED_BY_SERIAL_DIR, "%x.pem" % cert.serial))
+
     # Copy filesystem attributes to newly signed certificate
     if revoked_path:
         for key in listxattr(revoked_path):

certidude/cli.py

@@ -736,7 +736,6 @@ def certidude_setup_authority(username, kerberos_keytab, nginx_config, country,
     pip("gssapi falcon cryptography humanize ipaddress simplepam humanize requests pyopenssl")
     click.echo("Software dependencies installed")
 
-    if not os.path.exists("/etc/apt/sources.list.d/nginx-stable-trusty.list"):
     os.system("add-apt-repository -y ppa:nginx/stable")
     os.system("apt-get update")
     if not os.path.exists("/usr/lib/nginx/modules/ngx_nchan_module.so"):
@@ -773,6 +772,7 @@ def certidude_setup_authority(username, kerberos_keytab, nginx_config, country,
     # Expand variables
     ca_key = os.path.join(directory, "ca_key.pem")
     ca_crt = os.path.join(directory, "ca_crt.pem")
+    sqlite_path = os.path.join(directory, "meta", "db.sqlite")
 
     try:
         pwd.getpwnam("certidude")
@@ -858,11 +858,29 @@ def certidude_setup_authority(username, kerberos_keytab, nginx_config, country,
             fh.write(env.get_template("server/server.conf").render(vars()))
         click.echo("Generated %s" % const.CONFIG_PATH)
 
-    if os.path.lexists(directory):
+    # Create directories with 770 permissions
-        click.echo("CA directory %s already exists, remove to regenerate" % directory)
+    os.umask(0o027)
-    else:
+    if not os.path.exists(directory):
-        click.echo("CA configuration files are saved to: {}".format(directory))
+        os.makedirs(directory)
 
+    # Create subdirectories with 770 permissions
+    os.umask(0o007)
+    for subdir in ("signed", "signed/by-serial", "requests", "revoked", "expired", "meta"):
+        path = os.path.join(directory, subdir)
+        if not os.path.exists(path):
+            click.echo("Creating directory %s" % path)
+            os.mkdir(path)
+        else:
+            click.echo("Directory already exists %s" % path)
+
+    # Create SQLite database file with correct permissions
+    if not os.path.exists(sqlite_path):
+        os.umask(0o117)
+        with open(sqlite_path, "wb") as fh:
+            pass
+
+    # Generate and sign CA key
+    if not os.path.exists(ca_key):
         click.echo("Generating %d-bit RSA key..." % const.KEY_SIZE)
 
         key = rsa.generate_private_key(
@@ -920,22 +938,6 @@ def certidude_setup_authority(username, kerberos_keytab, nginx_config, country,
 
         click.echo("Signing %s..." % cert.subject)
 
-        # Create directories with 770 permissions
-        os.umask(0o027)
-        if not os.path.exists(directory):
-            os.makedirs(directory)
-
-        # Create subdirectories with 770 permissions
-        os.umask(0o007)
-        for subdir in ("signed", "requests", "revoked", "expired", "meta"):
-            if not os.path.exists(os.path.join(directory, subdir)):
-                os.mkdir(os.path.join(directory, subdir))
-
-        # Create SQLite database file with correct permissions
-        os.umask(0o117)
-        with open(os.path.join(directory, "meta", "db.sqlite"), "wb") as fh:
-            pass
-
         # Set permission bits to 640
         os.umask(0o137)
         with open(ca_crt, "wb") as fh:
@@ -1106,6 +1108,13 @@ def certidude_serve(port, listen, fork, exit_handler):
 
     from certidude import config
 
+    # Rebuild reverse mapping
+    for cn, path, buf, cert, server in authority.list_signed():
+        by_serial = os.path.join(config.SIGNED_BY_SERIAL_DIR, "%x.pem" % cert.serial)
+        if not os.path.exists(by_serial):
+            click.echo("Linking %s to ../%s.pem" % (by_serial, cn))
+            os.symlink("../%s.pem" % cn, by_serial)
+
     # Process directories
     if not os.path.exists(const.RUN_DIR):
         click.echo("Creating: %s" % const.RUN_DIR)

certidude/config.py

@@ -34,12 +34,15 @@ REQUEST_SUBNETS = set([ipaddress.ip_network(j) for j in
     cp.get("authorization", "request subnets").split(" ") if j]).union(AUTOSIGN_SUBNETS)
 SCEP_SUBNETS = set([ipaddress.ip_network(j) for j in
     cp.get("authorization", "scep subnets").split(" ") if j])
+OCSP_SUBNETS = set([ipaddress.ip_network(j) for j in
+    cp.get("authorization", "ocsp subnets").split(" ") if j])
 
 AUTHORITY_DIR = "/var/lib/certidude"
 AUTHORITY_PRIVATE_KEY_PATH = cp.get("authority", "private key path")
 AUTHORITY_CERTIFICATE_PATH = cp.get("authority", "certificate path")
 REQUESTS_DIR = cp.get("authority", "requests dir")
 SIGNED_DIR = cp.get("authority", "signed dir")
+SIGNED_BY_SERIAL_DIR = os.path.join(SIGNED_DIR, "by-serial")
 REVOKED_DIR = cp.get("authority", "revoked dir")
 EXPIRED_DIR = cp.get("authority", "expired dir")
 

certidude/templates/server/server.conf

@@ -59,6 +59,9 @@ autosign subnets = 127.0.0.0/8 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16
 # Simple Certificate Enrollment Protocol enabled subnets
 scep subnets =
 
+# Online Certificate Status Protocol enabled subnets
+ocsp subnets = 0.0.0.0/0
+
 [logging]
 # Disable logging
 ;backend =