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Yesterday I pushed new PSPKI release with version number v3.3.0. New version is even more stable and even more powerful. More technical change list is moved to dedicated article: Release notes for PSPKI v3.3.0. In this (and, possibly next) blog post I would like to outline major changes/improvements to this release.
I bet that ADCS database access is one of the most popular features people love in my module. And there are reasons: I put a lot of efforts to simplify access to CA database and provide flexible filter options. For example, get certificates that will expire in next 30 days:
Hello world! Last time (year or so) I was busy on anything else but my module. Now I’m happy to announce that the project isn’t died, it is alive and new version is published.
This version doesn’t bring new commands, nor deprecate any. I think, command list is well-established and I don’t see anything useful to add. People doesn’t ask either. However there are things to work with code: refactor, optimize, make it cleaner and so on. Let’s look at what I’ve done here:
Initially, project was hosted at CodePlex which is died now. I moved all my sources to GitHub, documentation to my web site and used CodePlex as module download place.
Since CodePlex is done, the only real option to ship binaries was to use PowerShell Gallery. It is something new to me (I never used it till today) and was a bit lost there. But it appeared more easier than I thought. Starting with v3.2.7, the module is available on PowerShell Gallery: PSPKI. Please, provide feedback on your experience with getting PowerShell PKI module from gallery.
In the past, I used MSI installer to ship the module. It is still very good option to do that, because you can use various tools, like group policies or ConfigMgr to deploy the module within organization. Thanks to Caphyon Advanced Installer and their free NFR license (as a part of my Microsoft MVP award) I was able to do that. And their tool was really great and easy to use. However, my MVP award options are uncertain and PowerShell Gallery is an acceptable tradeoff, so there is no big need in MSI anymore.
Hey guys! I was silent for a while due to a lack of good topics to discuss. Today I want to present another piece of my class work at university for “Compiler Development” course. The task is to write a manual lexical parser for a language of my choice. I decided to take JSON language, because its syntax is relatively simple and requires most common techniques to parse. In addition, it has well-looking BNF grammar for custom parser implementations.
The purpose of lexical analysis is to read the source code and convert them to a sequence of tokens (lexemes) which are minimal parts of each language. It is important understand that lexical analysis doesn’t perform semantic (meaning) validation. That is, lexical analysis determines whether the source code can be written in a specific language’s alphabet. It doesn’t mean that the code will be executed successfully. Source code semantic is validated only after lexical analysis and uses its product (a set of tables, keywords, operators, literals, identifiers, etc.).
You can think that there is no need to write your own lexical parser, because there are LOTS of them. For example, PowerShell contains built-in JSON encoder and decoder via ConvertTo-JSON and ConvertFrom-JSON cmdlets. Though, these cmdlets completely hide parsing result and perform object conversion. You can’t access internal parser to look at exact results of the parsing. But results of lexical parsers are actively used in web. For example, JS-based syntax highlighters use lexical parser to split the source code into tokens and colorize or highlight them for better readability. And my website does it as well (though, not via JS). For example, all XML and PowerShell code snippets on my blog are colorized by using lexical parsers. For PowerShell code I’m using Tokenize method in System.Management.Automation.PSParser class. For XML strings I’m using custom XML tokenizer. And cororize them according to token types.
In previous post we gave an introduction into techniques to work with certificate revocation lists in PowerShell. We explored common steps to read CRL’s basic information, CRL extensions and revoked certificate collection. Today I will discuss about CRL handy shortcuts and signature validation.
In some environments, it is impossible to automatically copy CRLs from CA server to CRL distribution points or there is a scenario when PKI administrators run custom scripts to monitor CRL health status at CRL distribution points and update them if they are about to expire. For such purposes I maintain two shortcut methods to quickly identify required values.
CRL validity is determined by a NextUpdate field. If the current time passes that timestamp, the CRL is considered expired. To provide better validity handling, Microsoft use their own Next CRL Publish CRL extension. This extension contains a date/time value at which CA will issue new CRL. This value (when present) is always set prior to value in NextUpdate field to provide a time window to replicate newly published CRL across all distribution points prior existing CRLs expire. I have a good article on this subject: How ThisUpdate, NextUpdate and NextCRLPublish are calculated (v2). However, Next CRL Publish extension is presented in CRLs issued by Microsoft CAs and is absent in 3rd party CAs, as the result, next CRL publication date is determined solely by Next Update field. Moreover, there might be a case when CA is in the decommission process and issues its last CRL which is supposed to be valid infinitely.
Today I would like to summarize techniques on working with X.509 certificate revocation lists (CRL) in PowerShell. There are a lot of examples in my weblog, but most of this information is provided as context-specific addition to work in a given article’s context. Before talking about the subject, I’d like to put few words about the reason of this blog post and why it is written in that way.
As PowerShell evolves, it starts to cover more and new areas. And this process continues since PowerShell birth (in 2006). Systems administrators become more critical to script functionality. Previously, if something was not doable at all, we skipped that thing. With PowerShell we are able to do much more things. Maybe, not natively, maybe not in an elegant manner (say, through complex parsing), maybe very ugly, but we can do that right now. If community is interested in some area, they will develop a framework to make things easier and available to everyone.
One big area I’m interesting in is public key infrastructure, CryptoAPI, certificates and everything related to them. This happened several years ago (I recall it was in 2009) when I already was a passionate PowerShell enthusiast. Unfortunately, I realized that PowerShell has very-very basic support of certificate-related stuff. Mostly, this is due to poor support from underlying .NET platform. As the result, I attempted to start my big project to integrate cryptography into PowerShell through PS module and standalone scripts. Apparently, I was one of the first PS enthusiasts who started cryptography integration into PowerShell. I made huge work during these 7 years, went through tons of mistakes, bad choices, misunderstandings, trials and probes. It took 7 years and still continues. As of now, I have developed one of the best PowerShell module to work with PKI I’m aware of: PowerShell PKI. It is not just a module, it is a whole framework, which offers additional functionality through .NET-style objects and methods you can call from PS console. All this makes me confident in PowerShell PKI area.