System.Security.Cryptography.Rsa.Tests.RSAXml Test Suite Fails with Strings Differ/Containers Differ

[mdh1418]

Build Information

Build: https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1094166
Build error leg or test failing: System.Security.Cryptography.Rsa.Tests.RSAXml.FromToXml
Pull request: #117435

Error Message

Fill the error message using step by step known issues guidance.

{
  "ErrorMessage": "System.Security.Cryptography.Rsa.Tests.RSAXml",
  "ErrorPattern": "",
  "BuildRetry": false,
  "ExcludeConsoleLog": false
}

Known issue validation

Build: 🔎 https://dev.azure.com/dnceng-public/public/_build/results?buildId=1094166
Error message validated: [^(Strings|Collections) differ]
Result validation: ❌ Known issue did not match with the provided build.
Validation performed at: 7/15/2025 3:25:34 PM UTC

Known issue validation

Build: 🔎 https://dev.azure.com/dnceng-public/public/_build/results?buildId=1094166
Error message validated: [System.Security.Cryptography.Rsa.Tests.RSAXml]
Result validation: ✅ Known issue matched with the provided build.
Validation performed at: 7/15/2025 3:26:54 PM UTC

Report

Build	Definition	Step Name	Console log	Pull Request
1099777	dotnet/runtime	Send to Helix	Log	#117845

Build	Definition	Test	Pull Request
1101863	dotnet/runtime	System.Security.Cryptography.Tests.WorkItemExecution	#117917
1101670	dotnet/runtime	System.Security.Cryptography.Rsa.Tests.RSAXml.TestWrite16384Parameters	#117907
1101730	dotnet/runtime	System.Security.Cryptography.Tests.WorkItemExecution	#117914
1101528	dotnet/runtime	System.Security.Cryptography.Rsa.Tests.RSAXml.FromToXml	#117905
1101396	dotnet/runtime	System.Security.Cryptography.Tests.WorkItemExecution	#117398
1101210	dotnet/runtime	System.Security.Cryptography.Rsa.Tests.RSAXml.TestWrite16384Parameters	#117892
1101161	dotnet/runtime	System.Security.Cryptography.Rsa.Tests.RSAXml.TestWrite16384Parameters	#117333
1101058	dotnet/runtime	System.Security.Cryptography.Tests.Base64TransformsTests.ToBase64_TransformFinalBlock_MatchesConvert	#117831
1101149	dotnet/runtime	System.Security.Cryptography.Tests.WorkItemExecution	#116947
1100814	dotnet/runtime	System.Security.Cryptography.Csp.Tests.WorkItemExecution	#117812
1100700	dotnet/runtime	System.Security.Cryptography.Tests.WorkItemExecution
1100634	dotnet/runtime	System.Security.Cryptography.Tests.WorkItemExecution	#117679
1100448	dotnet/runtime	System.Security.Cryptography.Tests.WorkItemExecution	#117827
1100413	dotnet/runtime	System.Security.Cryptography.Tests.WorkItemExecution	#117868
1100351	dotnet/runtime	System.Security.Cryptography.Tests.WorkItemExecution
1100229	dotnet/runtime	System.Security.Cryptography.Rsa.Tests.RSAXml.FromToXml	#117817
1100214	dotnet/runtime	System.Security.Cryptography.Tests.WorkItemExecution	#117858
1100209	dotnet/runtime	System.Security.Cryptography.Tests.WorkItemExecution
1099989	dotnet/runtime	System.Security.Cryptography.Tests.WorkItemExecution	#117828
1099912	dotnet/runtime	System.Security.Cryptography.Tests.WorkItemExecution
1099878	dotnet/runtime	System.Security.Cryptography.Tests.Base64TransformsTests.ToBase64_TransformFinalBlock_MatchesConvert	#116445
1099864	dotnet/runtime	System.Security.Cryptography.Tests.Base64TransformsTests.RoundtripCryptoStream	#117828
1099803	dotnet/runtime	System.Security.Cryptography.Tests.WorkItemExecution	#117790
1099436	dotnet/runtime	System.Security.Cryptography.Tests.WorkItemExecution	#117796
1099243	dotnet/runtime	System.Security.Cryptography.Tests.WorkItemExecution	#116798
1099115	dotnet/runtime	System.Security.Cryptography.Tests.WorkItemExecution	#117745
1099020	dotnet/runtime	System.Security.Cryptography.Csp.Tests.WorkItemExecution	#117812
1098828	dotnet/runtime	System.Security.Cryptography.Csp.Tests.WorkItemExecution
1098715	dotnet/runtime	System.Security.Cryptography.Rsa.Tests.RSAXml.FromToXml	#117745
1098705	dotnet/runtime	System.Security.Cryptography.Rsa.Tests.RSAXml.FromToXml	#117616
1095831	dotnet/runtime	System.Security.Cryptography.Rsa.Tests.RSAXml.FromToXml	#117398
1098140	dotnet/runtime	System.Security.Cryptography.Rsa.Tests.RSAXml.TestWriteUnusualExponentParameters	#117784
1096425	dotnet/runtime	System.Security.Cryptography.Dsa.Tests.DSAXml.TestWrite1024Parameters	#117716
1095810	dotnet/runtime	System.Security.Cryptography.Rsa.Tests.RSAXml.FromToXml	#116445
1095758	dotnet/runtime	System.Security.Cryptography.X509Certificates.Tests.RevocationTests.AiaTests.AiaAcceptsCertTypesAndIgnoresNonCertTypes	#117690
1095694	dotnet/runtime	System.Security.Cryptography.Rsa.Tests.RSAXml.FromToXml	#117685
1095670	dotnet/runtime	System.Security.Cryptography.Dsa.Tests.DSAXml.TestWrite512Parameters	#117584
1095634	dotnet/runtime	System.Security.Cryptography.Rsa.Tests.RSAXml.FromToXml	#117607
1094947	dotnet/runtime	System.Security.Cryptography.Csp.Tests.WorkItemExecution	#117653
1094166	dotnet/runtime	System.Security.Cryptography.Rsa.Tests.RSAXml.FromToXml	#117435
1092169	dotnet/runtime	System.Security.Cryptography.Rsa.Tests.RSAXml.TestWrite16384Parameters	#117537

Summary

24-Hour Hit Count	7-Day Hit Count	1-Month Count
10	40	42

[dotnet-policy-service]

Tagging subscribers to this area: @dotnet/area-system-security, @bartonjs, @vcsjones
See info in area-owners.md if you want to be subscribed.

[vcsjones]

Posting (one of) the failures so others don't need to go log spelunking.

Either way, it seems like RSA keys are being serialized differently. This was on mcr.microsoft.com/dotnet-buildtools/prereqs:alpine-3.22-helix-amd64.

ystem.Security.Cryptography.Rsa.Tests.RSAXml.TestWriteUnusualExponentParameters(includePrivateParameters: True) [FAIL]
      Assert.Equal() Failure: Strings differ
                  ↓ (pos 1)
      Expected: "9rqCgyYMOZEbi12xig/zanjVWagNZCk90Aw1h1YAm"···
      Actual:   "9AqAgAYAOAEAiA2AiA/AaAjAWAgAZAkA0AwAhAYAm"···
                  ↑ (pos 1)
      Stack Trace:
        /_/src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/RSA/RSAXml.cs(1459,0): at System.Security.Cryptography.Rsa.Tests.RSAXml.AssertNextElement(IEnumerator`1 iter, String localName, String expectedValue, String alternateValue)
        /_/src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/RSA/RSAXml.cs(1405,0): at System.Security.Cryptography.Rsa.Tests.RSAXml.TestWriteXml(RSAParameters& keyParameters, Boolean includePrivateParameters, String expectedModulus, String expectedExponent, String expectedD, String expectedP, String expectedQ, String expectedDP, String expectedDQ, String expectedInverseQ, String alternateD)
        /_/src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/RSA/RSAXml.cs(942,0): at System.Security.Cryptography.Rsa.Tests.RSAXml.TestWriteUnusualExponentParameters(Boolean includePrivateParameters)
           at System.RuntimeMethodHandle.InvokeMethod(ObjectHandleOnStack target, Void** arguments, ObjectHandleOnStack sig, BOOL isConstructor, ObjectHandleOnStack result)
           at System.RuntimeMethodHandle.InvokeMethod(ObjectHandleOnStack target, Void** arguments, ObjectHandleOnStack sig, BOOL isConstructor, ObjectHandleOnStack result)
        /_/src/coreclr/System.Private.CoreLib/src/System/Reflection/MethodBaseInvoker.CoreCLR.cs(36,0): at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
        /_/src/libraries/System.Private.CoreLib/src/System/Reflection/MethodBaseInvoker.cs(174,0): at System.Reflection.MethodBaseInvoker.InvokeDirectByRefWithFewArgs(Object obj, Span`1 copyOfArgs, BindingFlags invokeAttr)
    System.Security.Cryptography.Rsa.Tests.RSAXml.TestWriteUnusualExponentParameters(includePrivateParameters: False) [FAIL]

[bartonjs]

That seems... bad?

-f6 ba 82 83 26 0c 39 91 1b 8b 5d b1 8a 0f f3 6a 78 d5 59 a8 0d 64 29 3d d0 0c 35 87 56 00 ...
+f4 0a 80 80 06 00 38 01 00 88 0d 80 88 0f c0 68 08 c0 58 08 00 64 09 00 d0 0c 00 84 06 00 ...

It's like something is clearing every other 6 bits?

• F4BA XOR F40A is 02B0: 0b0000_0010_1011_0000
• 8B5D XOR 880D is 0350: 0b0000_0011_0101_0000

[vcsjones]

@bartonjs Since base64 is a 6-bit map... I wonder if this is a base64 encoding problem.

[bartonjs]

And here I was wondering what sort of data mutation test we had that was accidentally messing up an RSAParameter. Something bad happening in Base64 seems better aligned to the problem... and matches that every other character in the Actual is A (000000)

[vcsjones]

Same thing in other runs:

Expected: "myxwX6kQNx+LSMao1StC1p5rKCEwcBjzI136An3B/"···
Actual:   "mAxAXAkANA+ASAaA1AtA1A5AKAEAcAjAIA3AAA3A/"···

[dotnet-policy-service]

Tagging subscribers to this area: @dotnet/area-system-runtime
See info in area-owners.md if you want to be subscribed.

[vcsjones]

Marking this as System.Runtime because this suspiciously looks like a base64 encoding problem. Every other six bits are zeroed.