[Question] [Android] Crash due to crypto asserts

[ShortDevelopment]

I'm currently experiencing this exact issue (#61783) during calls involving hmac such as...

• ECDiffieHellman.DeriveKeyFromHmac
• HKDF.Expand

This issue has already been fixed in #61827.

My question is: How can I now use the fixed runtime version?
I'm targeting net6.0-android31.0 (.net 6.0.402 sdk).

Sorry for opening an issue for that...

[dotnet-issue-labeler]

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[ghost]

Tagging subscribers to 'arch-android': @steveisok, @akoeplinger
See info in area-owners.md if you want to be subscribed.

Issue Details

---

I'm currently experiencing this exact issue (#61783) during calls involving hmac such as...

• ECDiffieHellman.DeriveKeyFromHmac
• HKDF.Expand

This issue has already been fixed in #61827.

My question is: How can I now use the fixed runtime version?
I'm targeting net6.0-android31.0 (.net 6.0.402 sdk).

Sorry for opening an issue for that...

Author:	ShortDevelopment
Assignees:	-
Labels:	os-android, untriaged
Milestone:	-

[ghost]

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

Issue Details

---

I'm currently experiencing this exact issue (#61783) during calls involving hmac such as...

• ECDiffieHellman.DeriveKeyFromHmac
• HKDF.Expand

This issue has already been fixed in #61827.

My question is: How can I now use the fixed runtime version?
I'm targeting net6.0-android31.0 (.net 6.0.402 sdk).

Sorry for opening an issue for that...

Author:	ShortDevelopment
Assignees:	-
Labels:	question, area-System.Security, os-android, untriaged
Milestone:	-

[vcsjones]

#61827 didn't make the cut for .NET 6, so it's only present in .NET 7. Can you confirm if the issue is resolved in the RC2 for .NET 7?

I'm currently experiencing this exact issue (#61783) during calls involving hmac such as...

HKDF.Expand

Looks like that can happen when an empty info is passed to HKDF (an entirely reasonable thing to do)

runtime/src/libraries/System.Security.Cryptography/src/System/Security/Cryptography/HKDF.cs

Line 167 in 7d06aff

hmac.AppendData(infoBuffer);

which will trip the abort.

ECDiffieHellman.DeriveKeyFromHmac

For ECDH the assert will trip if the secretPrepend or secretAppend are empty (an entirely reasonable thing to do)

runtime/src/libraries/Common/src/System/Security/Cryptography/ECDiffieHellmanDerivation.cs

Line 28 in 7d06aff

hash.AppendData(secretPrepend);

So that explains where/why those APIs are hitting the empty HMAC update.

@bartonjs @steveisok do we want to fix this for .NET 6? Since those higher-level primitives can hit the abort when passing empty data to HMAC, there isn't much consumers can do about that. If we want to backport something, I can prepare a backport PR.

[bartonjs]

Yeah, process crashes are bad. We should service them.

Are all of these already fixed in 7 and we just need to backport to 6?

[vcsjones]

Are all of these already fixed in 7 and we just need to backport to 6?

To my knowledge, yes. I will start a backport PR.

[steveisok]

I think backporting to 6 is fine and low risk.

[ShortDevelopment]

Thanks for your quick response!

Can you confirm if the issue is resolved in the RC2 for .NET 7?

I tried to test that, but I couldn't get my android project to compile with the net7.0 preview in the limited amount of time I had.

Looks like that can happen when an empty info is passed to HKDF

That’s exactly my scenario!

I can prepare a backport PR

If you could successfully backport the fix, that would be great!

[vcsjones]

If you could successfully backport the fix, that would be great!

A backport PR has been opened for this at #77283. That doesn't definitely mean it's going to be fixed for .NET 6, yet. It still needs approval for servicing.

[vcsjones]

The backport PR has been approved and merged, and should be in .NET 6.0.12 when it's released. I don't think there is anything else this issue is tracking, so closing this out.