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//go:build !windows
// Copyright (c) 2018, Ian Haken. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package main
import (
"crypto/sha1"
"crypto/x509"
"flag"
"fmt"
"os"
"strconv"
"strings"
"github.com/google/go-tpm/tpm"
)
func generateAction() {
var tpmname = flag.String("tpm", "/dev/tpm0", "The path to the TPM device to use")
var keyblobPath = flag.String("keyblob", "keyblob", "Output path of the generated keyblob")
var pubKeyPath = flag.String("public-key", "publickey", "Output path of the generated keyblob's public key")
var pcrsStr = flag.String("pcrs", "", "A comma-separated list of PCR numbers against which the generated key will be bound. If blank, it will not be bound to any PCR values.")
flag.CommandLine.Parse(os.Args[2:])
var pcrs []int
if *pcrsStr != "" {
for _, pcr := range strings.Split(*pcrsStr, ",") {
pcrNum, err := strconv.Atoi(pcr)
if err != nil {
fmt.Fprintf(os.Stderr, "Bad value in pcrs argument: %s\n", pcr)
return
}
pcrs = append(pcrs, pcrNum)
}
}
rwc, err := tpm.OpenTPM(*tpmname)
if err != nil {
fmt.Fprintf(os.Stderr, "Couldn't open the TPM file %s: %s\n", *tpmname, err)
return
}
defer rwc.Close()
// Compute the auth values as needed.
var srkAuth [20]byte
srkInput := os.Getenv(srkAuthEnvVar)
if srkInput != "" {
sa := sha1.Sum([]byte(srkInput))
copy(srkAuth[:], sa[:])
}
var usageAuth [20]byte
usageInput := os.Getenv(usageAuthEnvVar)
if usageInput != "" {
ua := sha1.Sum([]byte(usageInput))
copy(usageAuth[:], ua[:])
}
var migrationAuth [20]byte
migrationInput := os.Getenv(migrationAuthEnvVar)
if migrationInput != "" {
ma := sha1.Sum([]byte(migrationInput))
copy(migrationAuth[:], ma[:])
}
keyblob, err := tpm.CreateWrapKey(rwc, srkAuth[:], usageAuth, migrationAuth, pcrs)
if err != nil {
fmt.Fprintf(os.Stderr, "Couldn't make a new signing key: %s\n", err)
return
}
fmt.Printf("Writing keyblob to %s\n", *keyblobPath)
if err = os.WriteFile(*keyblobPath, keyblob, 0644); err != nil {
fmt.Fprintf(os.Stderr, "Error writing keyblob file: %s\n", err)
return
}
pubKey, err := tpm.UnmarshalRSAPublicKey(keyblob)
if err != nil {
fmt.Fprintf(os.Stderr, "Could not get public key: %s\n", err)
return
}
pubKeyBytes, err := x509.MarshalPKIXPublicKey(pubKey)
if err != nil {
fmt.Fprintf(os.Stderr, "Could not marshal public key: %s\n", err)
return
}
fmt.Printf("Writing public key to %s\n", *pubKeyPath)
if err = os.WriteFile(*pubKeyPath, pubKeyBytes, 0644); err != nil {
fmt.Fprintf(os.Stderr, "Error writing public key file: %s\n", err)
return
}
}
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