File-based Certificate Cache

# Create a store that returns paths to the files it created, also choose an encoding for saving the files
## DER return 3 paths (cert, key, chain) , the chain is a tar archive with a der encoded file per cert in chain
## PEM and PKCS12 return 1 path
certStore = ondiskPathStore("/tmp/certs", encoding=Encoding.PEM)

# First argument is the certificate to use the format for a file based certificate is:
## A tuple with 3 elements: <filepath:str>, <cert_name:str|None>, <password:str|None>
## Or a single string: <filepath:str>
ca = CertificateAuthority(('my-ca.pem', 'My Custom CA', None), cache=certStore)

(filename,) = ca['example.com']

In this configuration, the root CA is stored at my-ca.pem and dynamically generated certs are placed in /tmp/certs. The filename returned would be /tmp/certs/example.com.pem in this example.

This filename can then be used with the Python ssl.load_cert_chain(certfile) command.

Note that the dynamically created certs are never deleted by certauth, it remains up to the user to handle cleanup occasionally if desired.

In-memory Certificate Cache

from certauth2 import CertificateAuthority
ca = CertificateAuthority(
   ("My Custom CA", "my-ca.pem", None), cache=50
)
key, cert, chain = ca["example.com"].to_pyopenssl()

This configuration stores the root CA at my-ca.pem but uses an in-memory certificate cache for dynamically created certs. By default the default store returns X509Credentials which are just a NamedTuple of (cert, key, chain) in cryptography format with methods to help load, dump and transform them into other formats.

These certs are stored in an LRU cache, configured to keep at most 50 certs.

The cert and key can then be used with OpenSSL.SSL.Context.use_certificate

context = SSl.Context(...)
context.use_privatekey(key)
context.use_certificate(cert)
for ca in chain:
   context.add_extra_chain_cert(ca)

Custom Cache

A custom cache implementations which stores and retrieves per-host certificates can also be provided:

from certauth2 import CertificateAuthority
from certauth2.cache import Cache

class PyOpenSSLCredentialStore(Cache):
   def __init__(self):
      self._cache = {}

   def __setitem__(self, key, item):
      self._cache[key] = item.to_pyopenssl()

   def __getitem__(self, key):
      return self._cache[key]

ca = CertificateAuthority('my-ca.pem', cache=PyOpenSSLCredentialStore())
key, cert, chain = ca['example.com']
context = SSl.Context(...)
context.use_privatekey(key)
context.use_certificate(cert)
for ca in chain:
   context.add_extra_chain_cert(ca)

Wildcard Certs

To reduce the number of certs generated, it is convenient to generate wildcard certs. For full functionality also install tld library

creds = ca.load_creds('test.example.com', domain_cert=True)

This will generate a cert for *.example.com.

creds = ca.load_creds('test.example.com', sans=["*.test.example.com"])

This will also generate a cert for *.test.example.com and test.example.com

creds = ca.load_creds('test.example.com', domain_cert=True, sans=["*.test.example.com"])

This will also generate a cert for *.test.example.com, test.example.com and *.example.com

Alternative FQDNs or IPs in SAN

Sometimes, you want to add alternative FQDNs or IPs as Subject Alternative Names to your certificate. To do that, simply use the sans params:

creds = ca.load_cert('example.com', sans=['example.org','192.168.1.1'])

This will generate a cert for example.com with example.org and 192.168.1.1 in the SAN.

Each san can be an ip as str|IPv4Address|IPv6Address a dns as str or x509.GeneralName