Monday, July 30, 2018

A Fairy Tale of an Old Music Box

One of things I really like doing in my spare time is playing the piano we bought recently. I also decided to check whether there is some decent score writing software out there and I was really surprised to find that the software not only gets much, much better over years but also that there are even some free yet advanced apps like the MuseScore.

Anyway, this looks like my chance to write down few ideas I had on my mind for all these years since I finished my music education. And since sharing is one of nice features of the software, please enjoy one of my compositions, the first one I wrote down with MuseScore, A Fairy Tale of an Old Music Box.

A Fairy Tale of an Old Music Box

Friday, July 13, 2018

.NET 4.7.1 (and higher) no longer supports SHA1 in SignedXml

There are plenty of subtle changes between .NET 4.7.0 (and lower) and .NET 4.7.1, however one of the changes hurt us badly. It looks like the SignedXml no longer supports SHA1 as the hashing method.

What it causes is the

System.Security.Cryptography.CryptographicException : Invalid algorithm specified
     at System.Security.Cryptography.Utils.SignValue(SafeKeyHandle hKey, Int32 keyNumber, Int32 calgKey, Int32 calgHash, Byte[] hash, Int32 cbHash, ObjectHandleOnStack retSignature)
     at System.Security.Cryptography.Utils.SignValue(SafeKeyHandle hKey, Int32 keyNumber, Int32 calgKey, Int32 calgHash, Byte[] hash)
     at System.Security.Cryptography.RSACryptoServiceProvider.SignHash(Byte[] rgbHash, Int32 calgHash)
     at System.Security.Cryptography.Xml.SignedXml.ComputeSignature()

The resolution is to put an additional section in the app's config file that switches the use of insecure hashes on:

    <AppContextSwitchOverrides value="Switch.System.Security.Cryptography.Xml.UseInsecureHashAlgorithms=true;
                                         Switch.System.Security.Cryptography.Pkcs.UseInsecureHashAlgorithms=true" />

If these switches seem to be ignored (we observed this in web apps where this was put in the web.config rather than an app.config, simply replace it with the code that you put in the global app class in the Application_Start:

protected void Application_Start(object sender, EventArgs e)
   AppContext.SetSwitch("Switch.System.Security.Cryptography.Xml.UseInsecureHashAlgorithms", true);
   AppContext.SetSwitch("Switch.System.Security.Cryptography.Pkcs.UseInsecureHashAlgorithms", true);

Monday, July 2, 2018

Integracja z ePUAP - dzień bez zmiany dniem straconym

Przed weekendem 30-06/01-07 blogowałem o zmianie na środowisku testowym ePUAP, przywracającym SHA1 w trybie wymuszenia (SHA256 przestało być obsługiwane) w konstruowaniu sygnatur WS-* w żądaniach do usług integracyjnych. Napisałem też że mam nadzieję na uporządkowanie sytuacji.

Cóż, sytuacja uporządkowała się o tyle że dziś (02-07) od południa na środowisku testowym ePUAP ( stoi kolejna wersja, która znów wymusza SHA256 i nie obsługuje SHA1.

Pytanie retoryczne: jak długo jeszcze może trwać ten kołowrotek i jak długo poczekamy na wersję która obsłuży oba rodzaje funkcji skrótu?