Golang tspi.Context類代碼示例

// GetEKCert reads the Endorsement Key certificate from the TPM's NVRAM and
// returns it, along with any error generated.
func GetEKCert(context *tspi.Context) (ekcert []byte, err error) {
	var wellKnown [20]byte
	tpm := context.GetTPM()
	nv, err := context.CreateNV()
	if err != nil {
		return nil, err
	}
	policy, err := tpm.GetPolicy(tspi.TSS_POLICY_USAGE)
	if err != nil {
		return nil, err
	}
	policy.SetSecret(tspi.TSS_SECRET_MODE_SHA1, wellKnown[:])
	nv.SetIndex(0x1000f000)
	nv.AssignPolicy(policy)
	data, err := nv.ReadValue(0, 5)
	if err != nil {
		return nil, err
	}

	tag := (uint)((uint)(data[0])<<8 | (uint)(data[1]))
	if tag != 0x1001 {
		return nil, fmt.Errorf("Invalid tag: %x", tag)
	}

	if data[2] != 0 {
		return nil, fmt.Errorf("Invalid certificate")
	}

	ekbuflen := (uint)(uint(data[3])<<8 | (uint)(data[4]))
	offset := (uint)(5)

	data, err = nv.ReadValue(offset, 2)

	tag = (uint)((uint)(data[0])<<8 | (uint)(data[1]))
	if tag == 0x1002 {
		offset += 2
		ekbuflen -= 2
	} else if data[0] != 0x30 {
		return nil, fmt.Errorf("Invalid header: %x\n", tag)
	}

	ekoffset := (uint)(0)
	var ekbuf []byte
	for ekoffset < ekbuflen {
		length := (uint)(ekbuflen - ekoffset)
		if length > 128 {
			length = 128
		}
		data, err = nv.ReadValue(offset, length)
		if err != nil {
			return nil, err
		}

		ekbuf = append(ekbuf, data...)
		offset += length
		ekoffset += length
	}

	return ekbuf, nil
}

func loadSRK(context *tspi.Context) (*tspi.Key, error) {
	srk, err := context.LoadKeyByUUID(tspiconst.TSS_PS_TYPE_SYSTEM, tspi.TSS_UUID_SRK)
	if err != nil {
		return nil, err
	}

	srkpolicy, err := srk.GetPolicy(tspiconst.TSS_POLICY_USAGE)
	if err != nil {
		return nil, err
	}
	srkpolicy.SetSecret(tspiconst.TSS_SECRET_MODE_SHA1, wellKnown[:])

	return srk, nil
}

// AIKChallengeResponse takes the output from GenerateChallenge along with the
// encrypted AIK key blob. The TPM then decrypts the asymmetric challenge with
// its EK in order to obtain the AES key, and uses the AES key to decrypt the
// symmetrically encrypted data. It verifies that this data blob corresponds
// to the AIK it was given, and if so hands back the secret contained within
// the symmetrically encrypted data.
func AIKChallengeResponse(context *tspi.Context, aikblob []byte, asymchallenge []byte, symchallenge []byte) (secret []byte, err error) {
	var wellKnown [20]byte

	srk, err := context.LoadKeyByUUID(tspi.TSS_PS_TYPE_SYSTEM, tspi.TSS_UUID_SRK)
	if err != nil {
		return nil, err
	}
	srkpolicy, err := srk.GetPolicy(tspi.TSS_POLICY_USAGE)
	if err != nil {
		return nil, err
	}
	srkpolicy.SetSecret(tspi.TSS_SECRET_MODE_SHA1, wellKnown[:])

	tpm := context.GetTPM()
	tpmpolicy, err := context.CreatePolicy(tspi.TSS_POLICY_USAGE)
	if err != nil {
		return nil, err
	}
	tpm.AssignPolicy(tpmpolicy)
	tpmpolicy.SetSecret(tspi.TSS_SECRET_MODE_SHA1, wellKnown[:])

	aik, err := context.LoadKeyByBlob(srk, aikblob)
	if err != nil {
		return nil, err
	}
	secret, err = tpm.ActivateIdentity(aik, asymchallenge, symchallenge)

	return secret, err
}

func cleanupContext(context *tspi.Context) {
	context.Close()
}

// CreateAIK asks the TPM to generate an Attestation Identity Key. It returns
// the unencrypted public half of the AIK along with an encrypted blob
// containing both halves of the key, and any error.
func CreateAIK(context *tspi.Context) ([]byte, []byte, error) {
	var wellKnown [20]byte
	n := make([]byte, 2048/8)
	for i := 0; i < 2048/8; i++ {
		n[i] = 0xff
	}

	srk, err := context.LoadKeyByUUID(tspi.TSS_PS_TYPE_SYSTEM, tspi.TSS_UUID_SRK)
	if err != nil {
		return nil, nil, err
	}
	keypolicy, err := srk.GetPolicy(tspi.TSS_POLICY_USAGE)
	if err != nil {
		return nil, nil, err
	}
	err = keypolicy.SetSecret(tspi.TSS_SECRET_MODE_SHA1, wellKnown[:])
	if err != nil {
		return nil, nil, err
	}

	tpm := context.GetTPM()
	tpmpolicy, err := tpm.GetPolicy(tspi.TSS_POLICY_USAGE)
	if err != nil {
		return nil, nil, err
	}
	err = tpm.AssignPolicy(tpmpolicy)
	if err != nil {
		return nil, nil, err
	}
	err = tpmpolicy.SetSecret(tspi.TSS_SECRET_MODE_SHA1, wellKnown[:])
	if err != nil {
		return nil, nil, err
	}

	pcakey, err := context.CreateKey(tspi.TSS_KEY_TYPE_LEGACY | tspi.TSS_KEY_SIZE_2048)
	if err != nil {
		return nil, nil, err
	}

	err = pcakey.SetModulus(n)
	if err != nil {
		return nil, nil, err
	}

	aik, err := context.CreateKey(tspi.TSS_KEY_TYPE_IDENTITY | tspi.TSS_KEY_SIZE_2048)
	if err != nil {
		return nil, nil, err
	}
	_, err = tpm.CollateIdentityRequest(srk, pcakey, aik)
	if err != nil {
		return nil, nil, err
	}

	pubkey, err := aik.GetPubKeyBlob()
	if err != nil {
		return nil, nil, err
	}
	blob, err := aik.GetKeyBlob()
	if err != nil {
		return nil, nil, err
	}

	_, err = aik.GetModulus()
	return pubkey, blob, nil
}