[release/11.0] Add managed Composite ML-KEM implementation by PranavSenthilnathan · Pull Request #134164 · dotnet/runtime

PranavSenthilnathan · 2026-09-17T23:11:05Z

Description

Implement Composite ML-KEM on OpenSSL-backed platforms. Straight backport;
no additional code changes. Stack layer 3/4, based on #134163, targeting RC2.

Customer Impact

Makes the new hybrid PQC APIs usable on OpenSSL-backed platforms where
the underlying algorithms are supported.

Regression

No. New API functionality.

Testing

Includes the original implementation tests and test vectors. Cherry-pick
equivalence and git diff --check passed; no local builds or tests run
for this layer.

Risk

Low. Implements new experimental APIs. Shared-helper changes preserve
existing callers' behavior.

Note

This PR description was generated with GitHub Copilot.

azure-pipelines · 2026-09-17T23:11:47Z

Azure Pipelines: Successfully started running 3 pipeline(s). 13 pipeline(s) were filtered out due to trigger conditions. There may be pipelines that require an authorized user to comment /azp run to run.

dotnet-policy-service · 2026-09-17T23:19:40Z

Tagging subscribers to this area: @bartonjs, @vcsjones, @dotnet/area-system-security
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bartonjs

Confirmed via patch-diffing that it's the same as existing commit 632117e.

PranavSenthilnathan · 2026-09-19T00:35:41Z

/ba-g #133311

artl93

New PQC. Approved.

main PR: #132440 # Description Add the experimental Composite ML-KEM base APIs, algorithm identifiers, and key import/export support. Straight backport; no additional code changes. Stack layer 2/4, based on #134162, targeting RC2. # Customer Impact Provides the new hybrid PQC API surface. Requires the implementation layers #134164 and #134165. # Regression No. New APIs. # Testing Includes the original contract and import/export tests. Cherry-pick equivalence verified; no local builds or tests run for this layer. # Risk Low. Adds new experimental APIs without changing existing API behavior. Ships together with the implementation layers. > [!NOTE] > This PR description was generated with GitHub Copilot. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: 5676db47-d54b-4946-97ec-7fc0a7392c30 Copilot-Session: 17bb5da2-badb-480f-a196-71dc1e23dc7b

Copilot

Copilot review overview

🟡 Changes recommended

The critical X25519 all-zero agreement validation issue remains unresolved; two project-file ordering nits also remain.

Get a fresh assessment by requesting another Copilot review.

Review effort: Lite
Findings: 1

Open (1)

Reject all-zero X25519 agreement in encapsulation · New

What changed in this PR

Adds managed Composite ML-KEM support for OpenSSL-backed platforms, combining ML-KEM with RSA, ECDH, and X25519.

Changes:

Adds composite KEM implementations and platform support wiring.
Adds ASN.1 handling and failure-path secret clearing.
Adds test vectors and implementation, factory, and contract tests.

File	Summary
`src/libraries/System.Security.Cryptography/tests/System.Security.Cryptography.Tests.csproj`	Includes Composite ML-KEM tests; vector entries require alphabetical reordering.
`src/libraries/System.Security.Cryptography/src/System/Security/Cryptography/MLKemImplementation.OpenSsl.cs`	Adds per-algorithm OpenSSL support detection.
`src/libraries/System.Security.Cryptography/src/System/Security/Cryptography/CompositeMLKemImplementation.Managed.cs`	Wires the managed Composite ML-KEM implementation.
`src/libraries/System.Security.Cryptography/src/System.Security.Cryptography.csproj`	Includes managed implementation sources.
`src/libraries/System.Security.Cryptography/src/Resources/Strings.resx`	Adds RSA decapsulation failure text.
`src/libraries/Microsoft.Bcl.Cryptography/tests/Microsoft.Bcl.Cryptography.Tests.csproj`	Includes shared test vectors; vector entries require alphabetical reordering.
`src/libraries/Common/tests/System/Security/Cryptography/AsnUtils.cs`	Supports span-based ASN.1 test inputs.
`src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/CompositeMLKem/CompositeMLKemTestVector.cs`	Defines test-vector representation.
`src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/CompositeMLKem/CompositeMLKemTestsBase.cs`	Provides shared Composite ML-KEM tests.
`src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/CompositeMLKem/CompositeMLKemTestData.cs`	Provides vector filtering and component metadata.
`src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/CompositeMLKem/CompositeMLKemImplementationTests.cs`	Tests the managed implementation.
`src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/CompositeMLKem/CompositeMLKemFactoryTests.cs`	Tests factories and key imports.
`src/libraries/Common/tests/System/Security/Cryptography/AlgorithmImplementations/CompositeMLKem/CompositeMLKemContractTests.cs`	Tests failure and secret-clearing contracts.
`src/libraries/Common/src/System/Security/Cryptography/RSAKeyFormatHelper.Pkcs1.cs`	Adds configurable ASN.1 encoding rules.
`src/libraries/Common/src/System/Security/Cryptography/MLKemImplementation.Windows.cs`	Adds Windows support-check parity.
`src/libraries/Common/src/System/Security/Cryptography/MLKemImplementation.NotSupported.cs`	Adds unsupported-platform support checks.
`src/libraries/Common/src/System/Security/Cryptography/CompositeMLKemManaged.XDiffieHellman.cs`	Implements X25519 composition; both paths require constant-time all-zero agreement rejection.
`src/libraries/Common/src/System/Security/Cryptography/CompositeMLKemManaged.RSA.cs`	Implements RSA-OAEP composition.
`src/libraries/Common/src/System/Security/Cryptography/CompositeMLKemManaged.ECDiffieHellman.cs`	Implements ECDH composition.
`src/libraries/Common/src/System/Security/Cryptography/CompositeMLKemManaged.cs`	Combines component KEMs and manages keys.
`src/libraries/Common/src/System/Security/Cryptography/CompositeMLKem.cs`	Clears shared-secret buffers on failures.

Managed Composite ML-KEM. This implementation is just for OpenSSL. Windows will have a native implementation added in a future PR. Contributes to #129633 --------- Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: 02fe9eac-5557-460a-aa50-d6a60a546192 Copilot-Session: 11ffe761-e9d2-47c2-ace0-857272c52b10 (cherry picked from commit 632117e)

artl93

Still approved.

PranavSenthilnathan · 2026-09-19T13:54:45Z

/ba-g #133311

main PR: #132687 # Description Add Windows Composite ML-KEM support, including BCrypt/NCrypt integration, CNG APIs, and key-blob handling. Straight backport; no additional code changes. Stack layer 4/4, based on #134164, targeting RC2. # Customer Impact Enables the new hybrid PQC APIs on Windows systems with supporting cryptographic providers. # Regression No. New APIs and platform implementation. # Testing Includes the original Windows provider, CNG, and key-blob tests. Cherry-pick equivalence verified; no local builds or tests run for this layer. # Risk Low. Adds support for new experimental APIs without changing existing cryptographic API behavior. > [!NOTE] > This PR description was generated with GitHub Copilot. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com> Copilot-Session: 67901feb-14f5-4029-bedd-84864cf3ea53 Copilot-Session: 11ffe761-e9d2-47c2-ace0-857272c52b10

dotnet-policy-service Bot assigned PranavSenthilnathan Sep 17, 2026

PranavSenthilnathan mentioned this pull request Sep 17, 2026

[release/11.0] Add Composite ML-KEM Windows implementation #134165

Merged

PranavSenthilnathan added this pull request to stack #134166 September 17, 2026 23:15

github-actions Bot added the area-System.Security label Sep 17, 2026

PranavSenthilnathan mentioned this pull request Sep 17, 2026

[release/11.0] Add Composite ML-KEM base APIs #134163

Merged

PranavSenthilnathan requested a review from bartonjs September 17, 2026 23:38

PranavSenthilnathan added this to the 11.0.0 milestone Sep 17, 2026

bartonjs approved these changes Sep 19, 2026

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PranavSenthilnathan added the Servicing-consider Issue for next servicing release review label Sep 19, 2026

PranavSenthilnathan requested a review from artl93 September 19, 2026 00:39

artl93 approved these changes Sep 19, 2026

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artl93 added Servicing-approved Approved for servicing release and removed Servicing-consider Issue for next servicing release review labels Sep 19, 2026

Copilot AI lite review requested due to automatic review settings September 19, 2026 04:24

artl93 force-pushed the ps-rc2-pqc-3-managed-ml-kem branch from 8c34b30 to 192c90e Compare September 19, 2026 04:24

Copilot started reviewing on behalf of PranavSenthilnathan September 19, 2026 04:25 View session

Base automatically changed from ps-rc2-pqc-2-ml-kem-base to release/11.0 September 19, 2026 04:28

Copilot AI reviewed Sep 19, 2026

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Comment thread src/libraries/Common/src/System/Security/Cryptography/CompositeMLKemManaged.XDiffieHellman.cs

PranavSenthilnathan force-pushed the ps-rc2-pqc-3-managed-ml-kem branch from 192c90e to d979aed Compare September 19, 2026 05:02

artl93 approved these changes Sep 19, 2026

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build-analysis Bot mentioned this pull request Sep 19, 2026

[Mono][browser] Double Min/Max do not preserve NaN sign and payload #133311

Open

artl93 merged commit 82b2ac8 into release/11.0 Sep 20, 2026
80 of 82 checks passed

artl93 deleted the ps-rc2-pqc-3-managed-ml-kem branch September 20, 2026 04:04

dotnet-maestro Bot mentioned this pull request Sep 20, 2026

[release/11.0.1xx] Source code updates from dotnet/runtime dotnet/dotnet#9542

Merged

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[release/11.0] Add managed Composite ML-KEM implementation - #134164

[release/11.0] Add managed Composite ML-KEM implementation#134164
artl93 merged 1 commit into
release/11.0from
ps-rc2-pqc-3-managed-ml-kem

PranavSenthilnathan commented Sep 17, 2026 •

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PranavSenthilnathan commented Sep 17, 2026 •

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