DI Management Services is a computer programming consultancy based in Australia and run by David Ireland. This is our home page. The Site Map lists things more concisely, and more info on the site is here. To contact us, please send us a message.
We do three things:
- Applied Cryptography: Protocols, Algorithms, and Source Code in C by Bruce Schneier. Look Inside
- Python Essential Reference by David Beazley. Look Inside
- The C Programming Language, 2nd Edition by Brian W. Kernighan and Dennis M. Ritchie. Look Inside
Affiliate disclosure: we get a small commission for purchases made through the above links
- 4 January 2018. A look at Bloom filters and a Bloom filter calculator to find the optimum parameters.
- 10 December 2017. New version 8.2 of FirmaSAT released.
- 28 August 2017. Updated version 1.6.3 of Wclock released.
- 8 August 2017. New version 11.2 of CryptoSys PKI Pro released. See new in the latest version. Plus an updated Python interface with improved documentation.
- 2 July 2017. Updated Windows utility hexdump is a simplified version of the Linux utility to display file contents in hexadecimal.
- 28 June 2017. Cryptography: Canonicalization of an XML document.
- 8 June 2017. Release new version 8.1 of FirmaSAT released with support for the new CFDi v3.3, Pagos10 and Contabilidad v1.3. See New in the Latest Version.
- 11 March 2017. New utility digestvalue to compute the digest value of a file in base64 encoding.
- 6 March 2017. Update to XML-Dsig and the Chile SII and Another C14N Example for Chile SII.
- 6 September 2016. Cryptography: How Mozilla signs Add-ons.
- 26 August 2016. Released a new Python interface to FirmaSAT.
- 15 August 2016. New version 5.2 of CryptoSys API released with support for the SCRYPT key derivation function. See changes in v5.2.
- 17 June 2016. New version 2.2 of bdcalc, a calculator for the large natural numbers as used in cryptography calculations.
- 12 June 2016. Introduced
a Python implementation of a side-by-side html diff program designed to run in Windows -
and wdiff for Windows,
a port of the original GNU
wdiffutility to Windows.
- 1 June 2016. C programming: Updated An all-singing, all-dancing C function to create a temporary file.
- 25 May 2016. Released our new Python interface to CryptoSys PKI Pro.
- 1 April 2016. Elliptic curve cryptography: Reproducing a raw Bitcoin transaction.
- 31 March 2016. New version 2.6 of our free ANSI C BigDigits library to do arithmetic and number theoretical calculations with large integers. Now released under an MPLv2 license.
- 8 March 2016. New version 11.0 of CryptoSys PKI Pro released with elliptic curve cryptography.
- 27 January 2016. A complete re-write of our Delphi/FreePascal Interfaces.
- 23 December 2015. C programming: Updated our page Getting rid of that MSVC++ warning C4996: 'may be unsafe/disable deprecation' for VS2013. This shows how to configure MSVC to default to an empty project with settings for real C programmers in a new Win32 Console project.
- 16 October 2015. Added a SHA-256 variant to our Freeware utilities to generate and check SHA-1, SHA-256, MD5 and CRC-32 checksums.
- 17 September 2015. Cryptography: Updated Test vectors for SHA-1, SHA-2 and SHA-3 to incorporate the new FIPS 202 SHA-3 Standard.
- 18 July 2015. New version 5.1 of CryptoSys API released with support for authenticated encryption with additional data (AEAD) using AES-GCM and AEAD-ChaCha20-Poly1305. See Using the AEAD functions.
- 30 June 2015. How to convert VBA/VB6 Unicode strings to UTF-8
- 27 March 2015. New product CryptoSys PKI Pro 1.0 released with new features.
- 28 January 2015. Cryptography: Verifying the test vectors for the Poly1305 Authenticator.
- 12 January 2015. New version 7.0 of FirmaSAT released, with support for `Contabilidad` and `Retenciones` documents.
- 21 December 2014. Upgraded Java Interface to FirmaSAT.
- 9 September 2014. Complete update of our page Data Exchange in the German Health Service with CryptoSys PKI.
- 4 September 2014. Released supplementary C/C++ Reference for CryptoSys PKI.
- 12 June 2014. Added a QR Code generator to the FirmaSAT On-line Validator.
- 11 June 2014. Reinstated our old tutorials on Microsoft Access Classes.
- 31 May 2014. Made DBXanalyzer available for free.
- 18 December 2013. Established the FirmaSAT On-line Validator page, an unofficial validator for Mexican "Comprobante" documents.
- 25 August 2013. Cryptography: Public key cryptography using discrete logarithms and the multiplicative group modulo p.
- 25 April 2013. Statistics: An on-line calculator for the binomial distribution.
- 22 March 2013. Updated the Converting from lex & yacc to flex & bison page and added Using flex and bison in MSVC++ .
- 4 March 2013. Number theory: Updated the Dirichlet character table generator
- 15 February 2013. Cryptography: Encrypting credit card numbers using Feistel Finite Set Encryption Mode (FFSEM)
- 15 January 2013. Statistics: An on-line calculator for the chi-square distribution.
- 19 November 2012. Set theory: De Morgan's laws explained in graphical form.
- 1 June 2012. Linear algebra: The theory behind Transforming a matrix to reduced row echelon form.
- 15 May 2012. Linear algebra: Added matrix calculator Transform matrix to row canonical form also called reduced row echelon form (RREF).
- 9 May 2012. Cryptography: Signing an XML document using XMLDSIG (Part 2).
- 18 November 2011. Coding Theory: Added matrix calculator Transforming a generator matrix to standard form.
- 17 November 2011. Number theory: Updated the Euclidean Algorithm page with code showing how to use the binary GCD algorithm.
- 11-11-11. New version 2.3 of our BigDigits free source code and a new version of our Modular Arithmetic Freeware to do modular arithmetic calculations with large integers.
- 3 November 2011. Number theory: Complete re-write of RSA Theory page and a new mathematics page on Elementary Number Theory.
- August 2011. We have moved from Sydney to south-west Western Australia.
We maintain a detailed cryptography software page with useful free cryptographic software code
and various articles on cryptography.
The free code includes the Blowfish algorithm in VB6 and
the MySecret command-line freeware encryption utility.
The articles include
our page on the RSA Algorithm including the
Theory and proof of the RSA algorithm,
and various how-to pages such as
Using Keys in Cryptography,
Using Padding in Encryption,
Encryption with International Character Sets, and
We also publish cryptography-related articles on Mathematics.
...more details →
We sell two commercial cryptographic products under the CryptoSysTM brand name:
CryptoSys API and
CryptoSys PKI Pro.
CryptoSys API is a library of symmetrical cryptography tools
and CryptoSys PKI Pro provides
public key encryption and digital signatures.
is a separate product to create and read digital receipts specifically
for the Tax Administration Service in Mexico (SAT).
There are interfaces for programmers in
VBA/VB6, VB.NET/VB2005/VB20xx, C/C++, C#, Java and Python.
...more details →
We can provide consulting services on implementing cryptography in your programs.
In particular, we are happy to provide detailed programming help with implementing
CryptoSys API and the
CryptoSys PKI Toolkit.
...more details →
Just need someone to cut some code? Our founder David Ireland, GSSP-C, has many years experience in programming in a variety of languages, including C, Visual Basic, Microsoft Access, C#, Perl and Python..
We enjoy doing complex algorithms and arcane problems.
If we can't do it, we'll tell you up-front, so as not to waste your time.
We only start jobs we know we can finish.
...more details →
See our page on the C Programming Language where we've assembled links and copies of interesting or educational articles on C programming, look at Windows Win32 programming, and consider why we still prefer ANSI C to C++.
- Wclock is a free, customisable, always-on-top world time clock for Windows computers. The source code is provided.
- BigDigits is a free library of multiple-precision arithmetic routines written in ANSI C to carry out large natural number calculations.
- bdcalc, our command-line calculator and mini-programming language for large natural numbers.
- DBXanalyzerTM reads, analyses and manages email data files created by Microsoft Outlook Express 5 and 6. It has a simple GUI interface and is used by hundreds of happy users worldwide to recover and manage their old Outlook Express emails. 2014-05-31: Now available for free.
- Our Su Doku Solver was written in Excel VBA back in 2004 when the "fiendish" puzzles were first introduced by the Times. This solver will solve almost all Su Doku problems (and takes away all the fun!).
Web Site Design
- We created the website for our client at Nannup Caravan Park. Cheers to Ton and Jo.
To contact us, please send us a message.
This page last updated 4 January 2018