Having gone through several introductory posts covering background material such as CSP's, contexts, key containers and methods of key generation, we are now ready to delve into the actual cryptographic operations that use symmetric algorithms in detail.

In a prior post, I described the use of Windows CryptoAPI to compute message digests and message authentication codes which ensure integrity of messages. We now move on to the use of symmetric algorithms in cryptography, which can be used for both message confidentiality and integrity. Asymmetric algorithms will be covered in future posts. Refer to the introductory post in this series for the difference between the two.

In my prior post, I introduced several abstractions — Cryptographic Service Providers, cryptographic contexts and key containers — that are part of Windows CryptoAPI and promised to look at cryptographic keys next.

Well, I changed my mind, figuring it might be better to first talk about simpler operations that do not require the use of keys at all. This post thus describes the generation of hashes, message digests and message integrity codes using Windows CryptoAPI and TWAPI.

This is the second in a series of posts on the use of cryptography on Windows. The previous blog post introduced the basic concepts related to cryptography. Here we delve into how those concepts are implemented in Windows at a system or architectural level and of course, how one accesses them from Tcl. This will lay the ground for discussing the actual cryptographic operations in future posts.

Security is currently the No. 1 priority for the software industry; and if that's not the case, it should be, given the current state of affairs with daily reports of major computer break-ins, credit card fraud, identity theft etc. It is important for applications, and application writers, to be aware of these issues and make use of all available technologies to protect against attacks.

This post is about US encryption controls on open source software and what programmers need to do to comply with those regulations.

I must start with a caveat because I know practically nothing about the subject! Treat it as one person's understanding of the matter, not legal advice. I am not a lawyer, don't play one on TV or even actually know a real lawyer. I am writing this as an aid to others writing open source software in the hope it will make them aware of the concerned regulations.