103 lines
3.0 KiB
Go
103 lines
3.0 KiB
Go
// Copyright (c) 2016 Daniel Oaks <daniel@danieloaks.net>
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// released under the MIT license
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package mkcerts
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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/pem"
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"fmt"
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"math/big"
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"net"
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"os"
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"time"
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)
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// CreateCertBytes creates a testing ECDSA certificate, returning the cert and key bytes.
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func CreateCertBytes(orgName string, host string) (certBytes []byte, keyBytes []byte, err error) {
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validFrom := time.Now()
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validFor := 365 * 24 * time.Hour
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notAfter := validFrom.Add(validFor)
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priv, err := rsa.GenerateKey(rand.Reader, 2048)
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if err != nil {
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return
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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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return nil, nil, fmt.Errorf("failed to generate serial number: %s", err)
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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{orgName},
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},
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NotBefore: validFrom,
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NotAfter: notAfter,
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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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// TODO: allow explicitly listing allowed addresses/names
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template.IPAddresses = append(template.IPAddresses, net.ParseIP("127.0.0.1"))
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template.IPAddresses = append(template.IPAddresses, net.ParseIP("::1"))
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if host != "" {
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template.DNSNames = append(template.DNSNames, host)
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}
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template.DNSNames = append(template.DNSNames, "localhost")
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derBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, &priv.PublicKey, priv)
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if err != nil {
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return nil, nil, fmt.Errorf("Failed to create certificate: %s", err.Error())
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}
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certBytes = pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: derBytes})
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b, err := x509.MarshalPKCS8PrivateKey(priv)
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if err != nil {
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return nil, nil, fmt.Errorf("Unable to marshal private key: %v", err.Error())
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}
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pemBlock := pem.Block{Type: "PRIVATE KEY", Bytes: b}
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keyBytes = pem.EncodeToMemory(&pemBlock)
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return certBytes, keyBytes, nil
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}
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// CreateCert creates a testing ECDSA certificate, outputting the cert and key at the given filenames.
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func CreateCert(orgName string, host string, certFilename string, keyFilename string) error {
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certBytes, keyBytes, err := CreateCertBytes(orgName, host)
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if err != nil {
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return err
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}
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certOut, err := os.Create(certFilename)
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if err != nil {
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return fmt.Errorf("failed to open %s for writing: %s", certFilename, err.Error())
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}
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defer certOut.Close()
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_, err = certOut.Write(certBytes)
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if err != nil {
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return fmt.Errorf("failed to write out cert file %s: %s", certFilename, err.Error())
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}
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keyOut, err := os.OpenFile(keyFilename, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
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if err != nil {
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return fmt.Errorf("failed to open %s for writing: %s", keyFilename, err.Error())
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}
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defer keyOut.Close()
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_, err = keyOut.Write(keyBytes)
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if err != nil {
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return fmt.Errorf("failed to write out key file %s: %s", keyFilename, err.Error())
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}
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return nil
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}
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