src/chromiumos/tast/local/hwsec/attestation_local_va.go

// Copyright 2020 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

package hwsec

import (
	"context"
	"encoding/base64"
	"io/ioutil"
	"os"

	"chromiumos/tast/common/testexec"
	"chromiumos/tast/errors"
)

// LocalVA implements the VA functionality by hwsec-test-va binary.
type LocalVA struct{}

// NewLocalVA creates a new instance of LocalVA.
func NewLocalVA() *LocalVA {
	return &LocalVA{}
}

// GetDecodedVAChallenge get the VA challenge generated by hwsec-test-va.
func (rc *LocalVA) GetDecodedVAChallenge(ctx context.Context) ([]byte, error) {
	out, err := testexec.CommandContext(ctx, "hwsec-test-va", "generate").Output()
	if err != nil {
		return nil, errors.Wrap(err, "failed to create challenge")
	}
	dec, err := base64.StdEncoding.DecodeString(string(out))
	if err != nil {
		return nil, errors.Wrap(err, "failed to decode challenge")
	}
	return dec, err
}

// VerifyEncodedVAChallenge asks hwsec-test-va to verify the challenge response.
func (rc *LocalVA) VerifyEncodedVAChallenge(ctx context.Context, signedChallenge string) error {
	fd, err := ioutil.TempFile("", "tast-hwsec-test-va-challenge-response")
	if err != nil {
		return errors.Wrap(err, "error creating temp file")
	}
	defer os.Remove(fd.Name())
	defer fd.Close()

	if _, err := fd.WriteString(signedChallenge); err != nil {
		return errors.Wrap(err, "failed to write challenge response")
	}

	if _, err := testexec.CommandContext(ctx, "hwsec-test-va", "verify", "--input="+fd.Name()).CombinedOutput(); err != nil {
		return errors.Wrap(err, "verification failed")
	}
	return err
}