OpenVPN OpenSSL entry 22: invalid expiry date

fedoraopensslopenvpn

I attempted to generate some OpenVPN keys for a new employee the other day. Same procedure as normal. Nothing has changed in this area for months.

During the certificate generation I get the following error:

Using configuration from /etc/openvpn/easy-rsa/openssl.cnf
entry 22: invalid expiry date

After some searching, there doesn't appear to be a clear answer. Some sites said something about a database file index.txt becoming damaged. Others said that its something to do with the default_days setting in openssl.cnf. Other sites suggested its an OpenSSL bug.

Anyone have any clues?

UPDATE

After more research I have discovered that there is a bug with OpenSSL where the expiration date for the last generated certificate goes beyond the year 2050, and thus the date in the index.txt has two extra digits added to it for some reason, thus making the index.txt appear corrupted. I'm not sure how to fix this.

Best Answer

This is a 'Year 2038 Problem' bug! It seems that OpenVPN certificates cannot be generated which expire after Jan. 19, 2038. I'm using Ubuntu 10.04 and OpenVPN 2.1.0.

Related Solutions

OpenSSL – Certification Authority Root Certificate Expiry and Renewal

Keeping the same private key on your root CA allows for all certificates to continue to validate successfully against the new root; all that's required of you is to trust the new root.

The certificate signing relationship is based on a signature from the private key; keeping the same private key (and, implicitly, the same public key) while generating a new public certificate, with a new validity period and any other new attributes changed as needed, keeps the trust relationship in place. CRLs, too, can continue over from the old cert to the new, as they are, like certificates, signed by the private key.

So, let's verify!

Make a root CA:

openssl req -new -x509 -keyout root.key -out origroot.pem -days 3650 -nodes

Generate a child certificate from it:

openssl genrsa -out cert.key 1024
openssl req -new -key cert.key -out cert.csr

Sign the child cert:

openssl x509 -req -in cert.csr -CA origroot.pem -CAkey root.key -create_serial -out cert.pem
rm cert.csr

All set there, normal certificate relationship. Let's verify the trust:

# openssl verify -CAfile origroot.pem -verbose cert.pem
cert.pem: OK

Ok, so, now let's say 10 years passed. Let's generate a new public certificate from the same root private key.

openssl req -new -key root.key -out newcsr.csr
openssl x509 -req -days 3650 -in newcsr.csr -signkey root.key -out newroot.pem
rm newcsr.csr

And.. did it work?

# openssl verify -CAfile newroot.pem -verbose cert.pem
cert.pem: OK

But.. why? They're different files, right?

# sha1sum newroot.pem
62577e00309e5eacf210d0538cd79c3cdc834020  newroot.pem
# sha1sum origroot.pem
c1d65a6cdfa6fc0e0a800be5edd3ab3b603e1899  origroot.pem

Yes, but, that doesn't mean that the new public key doesn't cryptographically match the signature on the certificate. Different serial numbers, same modulus:

# openssl x509 -noout -text -in origroot.pem
        Serial Number:
            c0:67:16:c0:8a:6b:59:1d
...
            RSA Public Key: (1024 bit)
                Modulus (1024 bit):
                    00:bd:56:b5:26:06:c1:f6:4c:f4:7c:14:2c:0d:dd:
                    3c:eb:8f:0a:c0:9d:d8:b4:8c:b5:d9:c7:87:4e:25:
                    8f:7c:92:4d:8f:b3:cc:e9:56:8d:db:f7:fd:d3:57:
                    1f:17:13:25:e7:3f:79:68:9f:b5:20:c9:ef:2f:3d:
                    4b:8d:23:fe:52:98:15:53:3a:91:e1:14:05:a7:7a:
                    9b:20:a9:b2:98:6e:67:36:04:dd:a6:cb:6c:3e:23:
                    6b:73:5b:f1:dd:9e:70:2b:f7:6e:bd:dc:d1:39:98:
                    1f:84:2a:ca:6c:ad:99:8a:fa:05:41:68:f8:e4:10:
                    d7:a3:66:0a:45:bd:0e:cd:9d
# openssl x509 -noout -text -in newroot.pem
        Serial Number:
            9a:a4:7b:e9:2b:0e:2c:32
...
            RSA Public Key: (1024 bit)
                Modulus (1024 bit):
                    00:bd:56:b5:26:06:c1:f6:4c:f4:7c:14:2c:0d:dd:
                    3c:eb:8f:0a:c0:9d:d8:b4:8c:b5:d9:c7:87:4e:25:
                    8f:7c:92:4d:8f:b3:cc:e9:56:8d:db:f7:fd:d3:57:
                    1f:17:13:25:e7:3f:79:68:9f:b5:20:c9:ef:2f:3d:
                    4b:8d:23:fe:52:98:15:53:3a:91:e1:14:05:a7:7a:
                    9b:20:a9:b2:98:6e:67:36:04:dd:a6:cb:6c:3e:23:
                    6b:73:5b:f1:dd:9e:70:2b:f7:6e:bd:dc:d1:39:98:
                    1f:84:2a:ca:6c:ad:99:8a:fa:05:41:68:f8:e4:10:
                    d7:a3:66:0a:45:bd:0e:cd:9d

Let's go a little further to verify that it's working in real world certificate validation.

Fire up an Apache instance, and let's give it a go (debian file structure, adjust as needed):

# cp cert.pem /etc/ssl/certs/
# cp origroot.pem /etc/ssl/certs/
# cp newroot.pem /etc/ssl/certs/
# cp cert.key /etc/ssl/private/

We'll set these directives on a VirtualHost listening on 443 - remember, the newroot.pem root certificate didn't even exist when cert.pem was generated and signed.

SSLEngine on
SSLCertificateFile /etc/ssl/certs/cert.pem
SSLCertificateKeyFile /etc/ssl/private/cert.key
SSLCertificateChainFile /etc/ssl/certs/newroot.pem

Let's check out how openssl sees it:

# openssl s_client -showcerts -CAfile newroot.pem -connect localhost:443

Certificate chain
 0 s:/C=AU/ST=Some-State/O=Internet Widgits Pty Ltd/CN=server.lan
   i:/C=AU/ST=Some-State/O=Internet Widgits Pty Ltd/CN=root
-----BEGIN CERTIFICATE-----
...
-----END CERTIFICATE-----
 1 s:/C=AU/ST=Some-State/O=Internet Widgits Pty Ltd/CN=root
   i:/C=AU/ST=Some-State/O=Internet Widgits Pty Ltd/CN=root
-----BEGIN CERTIFICATE-----
MIICHzCCAYgCCQCapHvpKw4sMjANBgkqhkiG9w0BAQUFADBUMQswCQYDVQQGEwJB
...
-----END CERTIFICATE-----
(this should match the actual contents of newroot.pem)
...
Verify return code: 0 (ok)

Ok, and how about a browser using MS's crypto API? Gotta trust the root, first, then it's all good, with the new root's serial number:

newroot

And, we should still be working with the old root, too. Switch Apache's config around:

SSLEngine on
SSLCertificateFile /etc/ssl/certs/cert.pem
SSLCertificateKeyFile /etc/ssl/private/cert.key
SSLCertificateChainFile /etc/ssl/certs/origroot.pem

Do a full restart on Apache, a reload won't switch the certs properly.

# openssl s_client -showcerts -CAfile origroot.pem -connect localhost:443

Certificate chain
 0 s:/C=AU/ST=Some-State/O=Internet Widgits Pty Ltd/CN=server.lan
   i:/C=AU/ST=Some-State/O=Internet Widgits Pty Ltd/CN=root
-----BEGIN CERTIFICATE-----
...
-----END CERTIFICATE-----
 1 s:/C=AU/ST=Some-State/O=Internet Widgits Pty Ltd/CN=root
   i:/C=AU/ST=Some-State/O=Internet Widgits Pty Ltd/CN=root
-----BEGIN CERTIFICATE-----
MIIC3jCCAkegAwIBAgIJAMBnFsCKa1kdMA0GCSqGSIb3DQEBBQUAMFQxCzAJBgNV
...
-----END CERTIFICATE-----
(this should match the actual contents of origroot.pem)
...
Verify return code: 0 (ok)

And, with the MS crypto API browser, Apache's presenting the old root, but the new root's still in the computer's trusted root store. It'll automatically find it and validate the cert against the trusted (new) root, despite Apache presenting a different chain (the old root). After stripping the new root from trusted roots and adding the original root cert, all is well:

oldroot

So, that's it! Keep the same private key when you renew, swap in the new trusted root, and it pretty much all just works. Good luck!

Convert from P7B to PEM via OpenSSL

Try this:

$ openssl pkcs7 -inform der -in a.p7b -out a.cer

If it doesn't work, brings to a Windows machine and export follow this guide.

Best Answer

Related Solutions

OpenSSL – Certification Authority Root Certificate Expiry and Renewal

Convert from P7B to PEM via OpenSSL

Related Topic