I haven’t talked about r509 here in awhile, but since v0.5 just got tagged I thought I’d plug it again. r509 is a wrapper for the OpenSSL libraries in Ruby. It’s designed to allow you to do a wide variety of certificate authority related operations (issuance, revocation, CRL generation, OCSP responses, et cetera). There are also some ancillary gems that are under active development (r509-ca-http, r509-ocsp-responder, r509-validity-redis) which will gain more documentation as these projects progress.

Check it out, file issues, fork, and contribute!

Over at Viking Hammer my coworker Sean Schulte has written up a great article dissecting an issue we ran into regarding the way Ruby’s OpenSSL::X509::Name#to_a currently builds its array. He discusses the problem, the two solutions we came up with, and shares code examples. Go check it out!

I’ve put a new project up on Github. r509 is a CA written in Ruby which aims to do friendly wrapping around Ruby’s baroque OpenSSL bindings. It’s still in the early stages, but check it out if you’re interested and fork if you want to help it improve!

OpenSSL has an ocsp querying facility that can be useful if you’re testing a responder or just curious how the online certificate status protocol works. To use it:

openssl ocsp -issuer IssuingCert.txt -cert ServerCert.txt -url http://ocsp.wherever.com -CAfile CAchain.txt

Argument Breakdown

• -issuer is the issuing CA for the certificate you want to check (called IssuingCert.txt above). This can be a self-signed root or a subroot.
• -cert is the certificate you want to verify. If you know the serial number and don’t want to provide the cert file itself you can use -serial instead.
• -url is the URL of the OCSP responder for your cert. You can parse the certificate to find the end point. It will be under the Authority Information Access node inside the x509 extensions
• -CAfile is only required if you want to verify the response of the OCSP server.¹ You’ll need to place the self-signed root + whatever intermediates are necessary for the OCSP signing cert from the server to chain up to it.
• There are many other optional args, so check out the list just by typing “openssl ocsp”

OCSP Response

Here’s an example response where the certificate has been marked as revoked.

Response verify OK
ServerCert.txt: revoked
This Update: Nov 20 15:43:49 2010 GMT
Next Update: Dec  4 17:43:49 2010 GMT
Reason: unspecified
Revocation Time: Mar 31 21:37:52 2009 GMT

And one marked as acceptable.

Response verify OK
ServerCert.txt: good
This Update: Nov 20 11:20:51 2010 GMT
Next Update: Nov 27 11:20:51 2010 GMT

Responses can have several error status codes. Here’s the list of possible errors from RFC 2560.

malformedRequest      (1),  --Illegal confirmation request
internalError         (2),  --Internal error in issuer
tryLater              (3),  --Try again later
                            --(4) is not used
sigRequired           (5),  --Must sign the request
unauthorized          (6)   --Request unauthorized

Short and sweet. This command will parse and give you a list of revoked serial numbers:

openssl crl -inform DER -text -noout -in mycrl.crl

Most CRLs are DER encoded, but you can use -inform PEM if your CRL is not binary. If you’re unsure if it is DER or PEM open it with a text editor. If you see —–BEGIN X509 CRL—– then it’s PEM and if you see strange binary-looking garbage characters it’s DER.

As internationalized domain names (IDN) proliferate more people need to test with, and ultimately purchase, IDN certificates. If you need to generate a CSR or even a self-signed certificate for an internationalized domain follow these steps:

1. Take the UTF-8 characters and paste them into a punycode converter (also known as ASCII compatible encoding, or ACE).
2. The resulting converted text will be a fairly long string that starts with “xn--”. Copy the entire thing.
3. Now run this command.

For CSR generation¹:

openssl req -new -nodes -out mycsr.csr -keyout mykey.pem -newkey rsa:2048

For self-signed certificate generation²:

openssl req -new -nodes -x509 -days 3650 -out mycert.cer -keyout mykey.pem -newkey rsa:2048

Either way, follow the prompts and when you reach Common Name paste the text you copied from the punycode converter. Now you can submit your CSR to a certification authority or install the self-signed certificate for testing.

If you have a list of keys and SSL certs and don’t know which cert belongs with which key, here’s a script for you. It’s not efficient (nested for loop!), but it gets the job done quickly.¹

#!/bin/bash
for i in `ls *.key` 
do
key_mod=`openssl rsa -noout -in $i -modulus`
for j in `ls *.cer`
do
x509_mod=`openssl x509 -noout -in $j -modulus`
if [ "$x509_mod" == "$key_mod" ]; then
echo "$j matches $i"
fi 
done
done

We are fast approaching the date where NIST has recommended that end entities stop utilizing 1024-bit private keys. OpenSSL, however, currently defaults to creating 1024-bit keypairs. To create a 2048-bit private key and corresponding CSR (which you can send to a certificate authority to obtain your SSL certificate):

openssl req -new -nodes -newkey rsa:2048 -keyout mydomain.key -out mydomain.csr

This command will make a 2048-bit key, run the interactive prompt to populate the fields of the certificate signing request, and leave the private key unencrypted (-nodes). You can remove -nodes if you wish, but encrypting the private key will require you to type the password every time you start an application (like apache) that uses it.

Check if an SSL certificate and private key match in two simple commands. The OpenSSL commands below will require you to replace <file> with your file’s name.

For your SSL certificate:¹

openssl x509 -noout -modulus -in <file> | md5sum

For your RSA private key:

openssl rsa -noout -modulus -in <file> | md5sum

The output of these commands should be identical. If it isn’t, your keys do not match.

Recently I needed to do some performance testing of an SSL instance on a VM. I considered using JMeter, but decided to use OpenSSL to get a rudimentary picture instead.

To obtain a basic result, we connect to the server and pull the /index.php file. You can specify whatever file you’d like to download, or none at all if you simply want to test connections.¹

openssl s_time -www /index.php -new -connect www.trustwave.com:443

Your result will look something like this:

No CIPHER specified
Collecting connection statistics for 30 seconds
ttttttttttttttttttttttttttttttttttttttttttttttttttttttttt
159 connections in 5.82s; 27.32 connections/user sec, bytes read 62328
159 connections in 31 real seconds, 392 bytes read per connection

If you’d like to get more specific with performance testing you can even use the -ciphers parameter to explicitly choose the negotiated cipher. You can obtain a list of available ciphers with “openssl ciphers”.