- ALPHABET SOUP
- IMPLEMENTATION GUIDELINES
- INTERNET SITES
Crypt::OpenSSL::CA::Resources - A bibliography of documentations and tools that I found helpful for implementing X509 PKIs in Perl over all these years.
For a tutorial introduction to the concepts of PKI and X509, please refer to the appropriate Wikipedia articles (in particular http://en.wikipedia.org/wiki/Public_key_infrastructure and http://en.wikipedia.org/wiki/X.509).
Have some giggles while uncovering the bleak truth about the state of affairs in PKI-world with Peter Gutmann's crypto tutorials at http://www.cs.auckland.ac.nz/~pgut001/tutorial/index.html, and especially the one that deals with X509 PKI at http://www.cs.auckland.ac.nz/~pgut001/pubs/pkitutorial.pdf.
The X509 Style Guide, also by Peter Gutmann (http://www.cs.auckland.ac.nz/~pgut001/pubs/x509guide.txt), although partly outdated (e.g. as regards Unicode support) is the single most helpful resource one needs to develop and deploy a full-fledged X509 PKI.
A working, rugged implementation of "PKIX" in Crypt::OpenSSL::CA::AlphabetSoup that is GPL-licenced and covers all the bases, despite its being restricted from the "commercial" version. Definitely a reference implementation in the field (I know, since I helped write it!). http://idx-pki.idealx.org/index.en.html
The venerable, feature-rich but quirky and poorly documented cryptographic library that Crypt::OpenSSL::CA is built upon. Available on http://www.openssl.org/ (and also on https://www.openssl.org/, of course).
Of special interest is the
/usr/bin/openssl command-line tool, that serves as a Swiss army knife of crypto debugging from making and parsing certificates to debugging SSL. Actually
/usr/bin/openssl is powerful enough to serve as the sole foundation for a full-fledged PKI; this is almost what "IDX-PKI" does, but it is quirky (and therefore Crypt::OpenSSL::CA departs from that idea).
Here are a few tricks that I know by heart from typing them so often:
- Parsing a certificate and displaying the details
openssl x509 -noout -text -in cert.pem
or at an even lower level, using "dumpasn1":
openssl x509 -outform der -in cert.pem | dumpasn1 -
- Getting the modulus (unique public key identifier) of a certificate or private key
If both match, then the private key and certificate correspond to each other.
openssl x509 -noout -modulus -in cert.pem openssl rsa -noout -modulus -in key.pem
- Generating a self-signed certificate and matching private key for tests
openssl req -x509 -nodes -new -newkey 1024 -keyout key.pem -out cert.pem
cert.pemfiles can be used directly for a network server, or to build a toy CA.
- Building a toy CA
Under distros that sport a cooperative
openssl.cnf: this was tested on Ubuntu Edgy, your mileage may vary.
create a test directory and chdir into it
demoCA/newcerts; put the string
demoCA/serial; create an empty
create a key and a self-signed certificate for the CA as explained above, and save them respectively as
create a certificate request using
openssl ca -subj "/C=AU/ST=Some-State/O=Internet Widgits Pty Ltd/CN=test" \ -in user.req
Rinse and repeat, tweaking the command line and the contents of the
./demoCAsubdirectory until openssl is satisfied. Read the ca(3) man page to interpret and resolve the error messages.
Your certificate should appear in
./demoCA/newcertsafter a finite time (and tearing out only a minority subset of your hair).
For advanced usage, copy over the default
openssl.cnffile (usually to be found in
demoCAand tack a
-config ./openssl.cnfonto the
opensslcommand line. Then you can start mucking with X509 extensions and so on.
Any serious work towards contributing to Crypt::OpenSSL::CA requires promiscuity with OpenSSL's code base. I suggest reading and understanding
apps/ca.c first, comparing and contrasting with the XS code in Crypt::OpenSSL::CA which does roughly the same thing in a simpler and more modular way. Seasoned programmers will find the OpenSSL man pages of some limited help, and the command
grep -r some_identifier /usr/include/openssl to come in handy more often than not.
There is a succint overview of OpenSSL's whole API in a file named
doc/openssl.txt, to be found either in OpenSSL's source or possibly in the documentation directory of your distribution's openssl package (YMMV).
A tool to debug "ASN.1" in Crypt::OpenSSL::CA::AlphabetSoup data structures, more fault-tolerant than the
openssl asn1parse command (see "OpenSSL"). Available on "Peter Gutmann's site" and as a Debian package.
http://www.cs.auckland.ac.nz/~pgut001/ contains more crypto- and security-related stuff, and is always a pleasure to waste office time reading from.
http://www.alvestrand.no/objectid/ and http://oid.elibel.tm.fr/ are both databases of "OID" in Crypt::OpenSSL::CA::AlphabetSoups that together contain pretty much all OIDs known to mankind. The latter sports a search engine.
The RFCs and other standards describing PKIX (the X509 PKI) are, in suggested reading order:
Basics, security model, definition of the entities (EE, RA, CA), format of messages between these entities (that nobody in his right mind would bother to implement in this contrived way).
Distinguished Names ("DN" in Crypt::OpenSSL::CA::AlphabetSoup)
Certificate and CRL formats, extensions in certificates, certificate validation algorithm.
How one should set the
keyUsagebits in an X509 certificate.
Certificate request file format - One of the most popular ones (the great thing about standards, as the saying goes, is that there are so many to choose from...)
The other certificate request file format of importance to an Internet PKIX deployment (http://wp.netscape.com/eng/security/ca-interface.html). Used by all browsers of the Netscape family.
The specification of the Netscape certificate type X509v3 extension. Mostly obsolete, but it does make your certificates all that more christmas-treeish.
A transport and backup format for X509 key material. Allows for bundling a user's certificate, its matching private key (password-protected), and the chain of CA certificates and CRLs that certify the user's certificate, all into a single binary blob.