mirror of
https://github.com/google/go-attestation.git
synced 2024-12-18 20:47:57 +00:00
103 lines
2.4 KiB
Go
103 lines
2.4 KiB
Go
package main
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import (
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"crypto/rand"
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"crypto/rsa"
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"crypto/x509"
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"crypto/x509/pkix"
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"encoding/binary"
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"encoding/hex"
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"flag"
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"fmt"
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"math/big"
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"os"
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"os/exec"
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"strings"
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"time"
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)
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func ekPub() *rsa.PublicKey {
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out, err := exec.Command("tpm_getpubek", "-z").Output()
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if err != nil {
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fmt.Fprintf(os.Stderr, "Error: %v\n", err)
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os.Exit(1)
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}
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spl := strings.Split(string(out), "Public Key:")
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hexKey := strings.NewReplacer(" ", "", "\n", "", "\r", "", "\t", "").Replace(spl[1])
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modBytes, err := hex.DecodeString(hexKey)
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if err != nil {
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fmt.Fprintf(os.Stderr, "Error: %v\n", err)
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os.Exit(1)
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}
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return &rsa.PublicKey{
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N: new(big.Int).SetBytes(modBytes),
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E: 65537,
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}
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}
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func generateCertificate(pub *rsa.PublicKey) []byte {
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priv, err := rsa.GenerateKey(rand.Reader, 2048)
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if err != nil {
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fmt.Fprintf(os.Stderr, "Error: %v\n", err)
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os.Exit(1)
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}
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serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
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serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
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if err != nil {
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fmt.Fprintf(os.Stderr, "Error: %v\n", err)
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os.Exit(1)
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}
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template := x509.Certificate{
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SerialNumber: serialNumber,
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Subject: pkix.Name{
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Organization: []string{"Acme Co"},
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},
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NotBefore: time.Now(),
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NotAfter: time.Now().AddDate(1, 0, 0),
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KeyUsage: x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
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ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
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BasicConstraintsValid: true,
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}
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derBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, pub, priv)
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if err != nil {
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fmt.Fprintf(os.Stderr, "Error: %v\n", err)
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os.Exit(1)
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}
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return derBytes
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}
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func main() {
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flag.Parse()
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certBytes := generateCertificate(ekPub())
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f, err := os.OpenFile("/tmp/ekcert", os.O_RDWR|os.O_TRUNC|os.O_CREATE, 0755)
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if err != nil {
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fmt.Fprintf(os.Stderr, "Error: %v\n", err)
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os.Exit(1)
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}
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// Write the header as documented in: TCG PC Specific Implementation
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// Specification, section 7.3.2.
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f.Write([]byte{0x10, 0x01, 0x00})
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certLength := make([]byte, 2)
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binary.BigEndian.PutUint16(certLength, uint16(len(certBytes)))
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f.Write(certLength)
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f.Write(certBytes)
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f.Close()
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cmd := exec.Command("tpm_nvwrite", "-z", "-i", "268496896", "-f", "/tmp/ekcert")
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cmd.Stdout = os.Stdout
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cmd.Stderr = os.Stderr
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if err := cmd.Run(); err != nil {
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fmt.Fprintf(os.Stderr, "Error: %v\n", err)
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os.Exit(1)
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}
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}
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