What does HRESULT 0x80280027 (TPM_E_INAPPROPRIATE_SIG) mean?

TPM_E_INAPPROPRIATE_SIG

The signing input format is incompatible with the selected scheme

TPM_E_INAPPROPRIATE_SIG (0x80280027) means the TPM signing command rejects the form of the data to be signed, including extra DER/encoding information that the chosen TPM 1.2 scheme does not accept. This is different from signature verification failure.

Evidence to capture

Record signing scheme, key usage, exact input bytes, DER/padding structure, hash algorithm, and command ordinal. Compare the serialized input with the scheme-specific TPM 1.2 requirements.

Focused correction

Encode the signing input exactly as required for that TPM scheme or select a compatible signing scheme/key. Do not treat a deterministic format rejection as random TPM I/O failure.

Technical references

• TCG: TPM 1.2 Main Specification.
• TCG: TPM 1.2 Part 2 — Structures.
• TCG: TPM 1.2 Part 3 — Commands.
• Microsoft: TPM Base Services portal.