What does HRESULT 0x802800A6 (TPM_20_E_CURVE) mean?

TPM_20_E_CURVE

ECC support is device-specific in TPM 2.0. The specification defines an interface for curve identifiers, but each TPM implements only a capability-dependent subset. This error means the requested curve cannot be used in the command context, even if the operating system or another cryptographic library supports that curve.

What must agree

• The requested curveID must be implemented by the TPM.
• The public-key type must be ECC and the scheme must be valid for the selected curve and operation.
• Any imported point, key template or policy data must have been created for the same curve family and parameter sizes.

Diagnosis without guesswork

Query TPM ECC capabilities on the affected machine, record the curve identifier from the public template, and compare it with the application profile. Replacing the curve in isolation is unsafe: it can invalidate the public key, signatures, protocol peer expectations and sealed-object metadata.

TCG: ECC curve and public-key definitions · tpm2-tools: ECC public object algorithms · tpm2-tss: CreatePrimary public template