Bug 45168 - XmlDsigExcC14NTransform adds redundant namespace attribute
Summary: XmlDsigExcC14NTransform adds redundant namespace attribute
Status: NEW
Alias: None
Product: Class Libraries
Classification: Mono
Component: System.Security ()
Version: 4.2.3 (C6SR3)
Hardware: PC Linux
: --- normal
Target Milestone: Untriaged
Assignee: Bugzilla
Depends on:
Reported: 2016-10-07 12:51 UTC by ivan12
Modified: 2016-10-07 12:51 UTC (History)
1 user (show)

Is this bug a regression?: ---
Last known good build:

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Description ivan12 2016-10-07 12:51:38 UTC
XmlDsigExcC14NTransform can add redundant namespace attribute, so the resulting XML is not correctly canonicalized.
Sample code to reproduce this issue:

using System;
using System.IO;
using System.Security.Cryptography.Xml;
using System.Text;
using System.Xml;

public class Program
    public static void Main(string[] args)
        var doc = new XmlDocument();
        @"<ns1:A xmlns:ns1=""ns1""><B><ns1:C/></B></ns1:A>");
        var t = new XmlDsigExcC14NTransform();
        var ms = (MemoryStream)t.GetOutput();

When you run this code using Mono:

    mcs ./Program.cs -r:System.Security && mono ./Program.exe

the result is:

    <ns:A xmlns:ns="ns"><B><ns:C xmlns:ns="ns"></ns:C></B></ns:A>

When you run the same program using .NET Framework, you'll get the expected output (without namespace attribute in the C element):

   <ns:A xmlns:ns="ns"><B><ns:C></ns:C></B></ns:A>

This behaviour is caused by method XmlCanonicalizer.WriteNamespacesAxis, which incorrectly determines that namespace from A element is not visible and writes the same namespace attribute again in element C.