Add mTLS Bearer token design specification#5848
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This PR adds app-level support for sending confidential client certificates over **mTLS transport** independently from token type.
Today, `WithMtlsProofOfPossession()` effectively drives both:
- the **token type** (`mTLS PoP`)
- the **certificate transport path** (mTLS)
That makes it hard to express the missing scenario:
- **mTLS transport + Bearer token**
This change introduces a new certificate option:
```csharp
new CertificateOptions
{
SendCertificateOverMtls = true
}
```
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Pull request overview
Adds a design mini-spec documenting a proposed API/config change to decouple token type (Bearer vs mTLS PoP) from certificate transport (request-body assertion vs mTLS handshake) for confidential client certificates, enabling the “mTLS transport + Bearer token” scenario.
Changes:
- Introduces a new proposed
CertificateOptions.SendCertificateOverMtlsflag (design-level) and defines its intended semantics. - Documents precedence rules between app-level defaults and request-level
.WithMtlsProofOfPossession(). - Adds a behavior matrix plus validation/implementation/testing notes for the new scenario.
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bgavrilMS
approved these changes
Mar 31, 2026
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This PR adds app-level support for sending confidential client certificates over mTLS transport independently from token type.
Today,
WithMtlsProofOfPossession()effectively drives both:mTLS PoP)That makes it hard to express the missing scenario:
This change introduces a new certificate option:
This keeps token type and certificate transport as separate concerns: